Patent Publication Number: US-2023142998-A1

Title: Processing apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a processing apparatus that is configured to process an object by a processing light. 
     BACKGROUND ART 
     A Patent Literature 1 discloses, as a processing apparatus that is configured to process an object, a processing apparatus that is configured to form a structure by irradiating a surface of an object with a processing light. This type of processing apparatus is required to properly process the object. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1: U.S. Pat. No. 4,994,639B 
     SUMMARY OF INVENTION 
     A first aspect provides a processing apparatus that is configured to process an object by a processing light from a processing light source, wherein the processing apparatus includes: a first optical system that is configured to condense the processing light from the processing light source on a condensed plane; and a second optical system that is configured to condense the processing light from the first optical system to irradiate the object with it, a position in the condensed plane through which the processing light passes is changeable, a propagating direction of the processing light propagating from the first optical system to the second optical system changes depending on the passing position. 
     A second aspect provides a processing apparatus that is configured to process an object by a processing light from a processing light source, wherein the processing apparatus includes an irradiation optical system that is configured to condense the processing light to irradiate the object with it, the irradiation optical system emitting the processing light toward a surface that intersects with a plane perpendicular to an optical axis of the irradiation optical system. 
     A third aspect provides a processing apparatus that is configured to process an object by a processing light from a processing light source, wherein the processing apparatus includes: an irradiation optical system that is configured to condense the processing light to irradiate the object with it; and a movable optical member that is movable to change an irradiation position of the processing light with which the object is irradiated, a condensed position of the processing light from the irradiation optical system is changed in an annular area surrounding an optical axis of the irradiation optical system. 
     A fourth aspect provides a processing apparatus that is configured to process an object by a processing light from a processing light source, wherein the processing apparatus includes an irradiation optical system that is configured to condense the processing light to irradiate the object with it, the irradiation optical system includes an optical member that is located at the most object side along an optical path of the processing light among optical members included in the irradiation optical system and that has a meniscus shape in which a convex plane faces toward an exit side of the processing light. 
     A fifth aspect provides a processing apparatus that is configured to process an object by a processing light from a processing light source, wherein the processing apparatus includes an irradiation optical system that is configured to condense the processing light to irradiate the object with it, the irradiation optical system includes an optical member that is located at the most object side along an optical path of the processing light among optical members included in the irradiation optical system, a position on the object that is irradiated with the processing light emitted from the optical member is located at a position that is away from an object-side optical surface of the optical member located at the most object side toward an entrance side of the optical member along an optical axis direction of the irradiation optical system. 
     A sixth aspect provides a processing apparatus that is configured to process an object, which has a first surface and a second surface facing the first surface, by a processing light from a processing light source, wherein the processing apparatus includes: an objective optical system that is disposed to be located between the first surface and the second surface and that is configured to irradiate at least one of the first surface and the second surface with the processing light; and a movable optical member that is disposed on an processing optical path that is at the processing light source side from a position between the first surface and the second surface, an irradiation position of the processing light on at least one of the first surface and the second surface is changed by moving the movable optical member. 
     A seventh aspect provides a processing apparatus that is configured to process an object, which has a first surface and a second surface facing the first surface, by a processing light, wherein the processing apparatus includes: an objective optical system that is disposed to be located between the first surface and the second surface and that is configured to irradiate at least one of the first surface and the second surface with the processing light; a measurement part that is configured to optically receive, through the objective optical system, a light from at least one of the first surface and the second surface as a measurement light to measure at least one of the first surface and the second surface; and a movement part that is configured to move the objective optical system along a first direction that intersects with a direction connecting the first surface and the second surface, at least a part of at least one of the first surface and the second surface is measured when the movement part moves the objective optical system toward a first side along the first direction, at least a part of at least one of the first surface and the second surface is processed when the movement part moves the objective optical system toward a second side opposite to the first side along the first direction. 
     A eighth aspect provides a processing apparatus that is configured to process an object, which has a first surface and a second surface facing the first surface, by a processing light, wherein the processing apparatus includes: an objective optical system that is disposed to be located between the first surface and the second surface and that is configured to irradiate at least one of the first surface and the second surface with the processing light; and a suction part that is configured to suck a gas around the objective optical system from a lateral space of the objective optical system. 
     A ninth aspect provides a processing apparatus that is configured to process an object, which has a first surface and a second surface facing the first surface, by a processing light, wherein the processing apparatus includes: an objective optical system that is disposed to be located between the first surface and the second surface and that is configured to irradiate at least one of the first surface and the second surface with the processing light; and a supply part that is configured to supply a gas from a tip of the objective optical system. 
     A tenth aspect provides a processing apparatus that is configured to process an object by a processing light, wherein the processing apparatus includes: an objective optical system that is disposed to be located between a first surface and a second surface of the object and that is configured to irradiate at least one of the first surface and the second surface with the processing light; and a measurement part that is configured to optically receive, through the objective optical system, a light from at least one of the first surface and the second surface as a measurement light to measure at least one of the first surface and the second surface, the measurement part includes a imaging element that is configured to capture an image of at least one of the first surface and the second surface two-dimensionally. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a perspective view that conceptionally illustrates an exterior appearance of a processing system in a first example embodiment. 
         FIG.  2    is a system configuration diagram that illustrates a system configuration of the processing system in the first example embodiment. 
         FIG.  3    is a cross-sectional view that illustrates a configuration of a processing head. 
         FIG.  4    is a cross-sectional view that illustrates an optical path of a processing light in the processing head. 
         FIG.  5    is a cross-sectional view that illustrates the processing head at least a part of which is inserted into a space formed in a workpiece. 
         FIG.  6 A  is a perspective view that illustrates an aspect in which an irradiation position of the processing light illustrated in  FIG.  5    is changed by a Galvano mirror, and  FIG.  6 B  is a cross-sectional view that illustrates an aspect in which the irradiation position of the processing light illustrated in  FIG.  5    is changed by the Galvano mirror. 
         FIG.  7    is a cross-sectional view that illustrates an optical path of a measurement light in the processing head. 
         FIG.  8    is a perspective view that illustrates an area on a surface of the workpiece that is irradiated with the measurement light from an objective optical system. 
         FIG.  9    is a cross-sectional view that illustrates the processing head that has moved to a position at which it can be inserted into the space formed in the workpiece. 
         FIG.  10    is a top view that illustrates a marker formed on the workpiece. 
         FIG.  11    is a cross-sectional view that illustrates the processing head in a period during which a measurement operation is performed. 
         FIG.  12    is a cross-sectional view that illustrates the processing head in a period during which a processing operation is performed. 
         FIG.  13 A  is a cross-sectional view that illustrates an inner wall surface at which a concavity and convexity exists, and  FIG.  13 B  is a cross-sectional view that illustrates the inner wall surface after the processing operation is performed to smooth the concavity and convexity. 
         FIG.  14    is a perspective view that illustrates another example of the workpiece. 
         FIG.  15    is a cross-sectional view that illustrates a positional relationship between the workpiece and the objective optical system that is inserted into the space formed in the workpiece illustrated in  FIG.  14   . 
         FIG.  16    is a perspective view that illustrates another example of the workpiece. 
         FIG.  17    is a perspective view that illustrates another example of the workpiece. 
         FIG.  18    is a system configuration diagram that illustrates a system configuration of a processing system in a second example embodiment. 
         FIG.  19    is a cross-sectional view that illustrates an exhaust and gas supply member, a gas supply apparatus and an exhaust apparatus that are configured to suck a gas around the objective optical system from a lateral space of the objective optical system. 
         FIG.  20    is a cross-sectional view that illustrates another example of the exhaust and gas supply member. 
         FIG.  21    is a system configuration diagram that illustrates a system configuration of a processing system in a third example embodiment. 
         FIG.  22    is a cross-sectional view that illustrates an objective optical system and an exhaust and gas supply member in the third example embodiment. 
         FIG.  23    is a perspective view that conceptionally illustrates an exterior appearance of a processing system in a fourth example embodiment. 
         FIG.  24    is a cross-sectional view that illustrates a configuration of a processing head in a fifth example embodiment. 
         FIG.  25    is a perspective view that conceptionally illustrates an exterior appearance of a processing system in the sixth example embodiment. 
         FIG.  26    is a system configuration diagram that illustrates a system configuration of the processing system in the sixth example embodiment. 
         FIG.  27    is a cross-sectional view that illustrates a configuration of a processing head and a measurement head in the sixth example embodiment. 
         FIG.  28    is a system configuration diagram that illustrates a system configuration of a processing system in a seventh example embodiment. 
         FIG.  29    is a perspective view that illustrates another example of the workpiece. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Next, with reference to drawings, an example embodiment of a processing apparatus will be described. In the below described description, the example embodiment of the processing apparatus will be described by using a processing system SYS that is configured to process a workpiece W by using a processing light EL. However, the present invention is not limited to the below described embodiment. 
     Moreover, in the below described description, a positional relationship of various components that constitute the processing system SYS will be described by using an XYZ rectangular coordinate system that is defined by a X axis, a Y axis and a Z axis that are perpendicular to one another. Note that each of an X axis direction and a Y axis direction is assumed to be a horizontal direction (namely, a predetermined direction in a horizontal plane) and a Z axis direction is assumed to be a vertical direction (namely, a direction that is perpendicular to the horizontal plane, and substantially an up-down direction), for the purpose of simple description, in the below described description. Moreover, rotational directions (in other words, inclination directions) around the X axis, the Y axis and the Z axis are referred to as a θX direction, a θY direction and a θZ direction, respectively. Here, the Z axis direction may be a gravity direction. An XY plane may be a horizontal direction. 
     (1) Processing System SYSa in First Example Embodiment 
     Firstly, the processing system SYS in a first example embodiment (in the below described description, the processing system SYS in the first example embodiment is referred to as a “processing system SYSa”) will be described. 
     (1-1) Configuration of Processing System SYSa 
     Firstly, with reference to  FIG.  1    and  FIG.  2   , a configuration of the processing system SYSa in the first example embodiment will be described.  FIG.  1    is a perspective view that conceptionally illustrates an exterior appearance of the processing system SYSa in the first example embodiment.  FIG.  2    is a system configuration diagram that illustrates a system configuration of the processing system SYSa in the first example embodiment. 
     As illustrated in  FIG.  1    and  FIG.  2   , the processing system SYSa includes a processing apparatus  1 , a stage apparatus  2 , a measurement apparatus  3  and a control apparatus  4 . The processing apparatus  1 , the stage apparatus  2  and the measurement apparatus  3  are contained in a housing  5 . However, the processing apparatus  1 , the stage apparatus  2  and the measurement apparatus  3  may not be contained in the housing  5 . Namely, the processing system SYSa may not include the housing  5  in which the processing apparatus  1 , the stage apparatus  2  and the measurement apparatus  3  are contained. 
     The processing apparatus  1  is configured to processes the workpiece W under the control of the control apparatus  4 . The workpiece W may be a metal, may be an alloy (for example, a duralumin and the like), may be a semiconductor (for example, a silicon), may be a resin, may be a composite material such as a CFRP (Carbon Fiber Reinforced Plastic), may be a glass, may be a ceramic or may be an object that is made from any other material, for example. 
     The processing apparatus  1  irradiates the workpiece W with a processing light EL in order to process the workpiece W. The processing light EL may be any type of light, as long as the workpiece W is processed by irradiating the workpiece W with it. In the present embodiment, an example in which the processing light EL is a laser light will be described, however, the processing light EL may be a light a type of which is different from the laser light. Furthermore, a wavelength of the processing light EL may be any wavelength, as long as the workpiece W is processed by irradiating the workpiece W with it. For example, the processing light EL may be a visible light, may be an invisible light (for example, at least one of an infrared light, an ultraviolet light and the like). The processing light EL includes a pulsed light, however, may not include the pulsed light. In other words, the processing light EL may be a continuous light. 
     The processing apparatus  1  may perform a removal processing (typically, a cutting processing or a grinding processing) for removing a part of the workpiece W by irradiating the workpiece W with the processing light EL. The removal processing may include at least one of a surface cutting processing, a surface grinding processing, a cylindrical cutting processing, a cylindrical grinding processing, a drilling cutting processing, a drilling grinding processing, a surface polishing processing, a cutting-off processing and a carving processing for forming (in other words, carving) any character or any pattern. 
     When the removal processing is performed, the processing apparatus  1  may form a riblet structure on the workpiece W. The riblet structure is a structure by which a resistance (especially, at least one of a frictional resistance and a turbulent frictional resistance) of the surface of the workpiece W to a fluid is reducible. The riblet structure may include a structure in which a plurality of grooves each of which extends along a first direction (for example, the Y axis direction) that is along the surface of the workpiece W are arranged along a second direction (for example, the X axis direction) that is along the surface of the workpiece W and that intersects with the first direction, for example. 
     The processing apparatus  1  may perform an additive processing for adding new structural object to the workpiece W by irradiating the workpiece W with the processing light EL, in addition to or instead of the removal processing. In this case, the processing apparatus  1  may form the above described riblet structure on the workpiece W by performing the additive processing. The processing apparatus  1  may perform a marking processing for forming a desired mark on a surface of the workpiece W by irradiating the workpiece W with the processing light EL, in addition to or instead of at least one of the removal processing and the additive processing. 
     The processing apparatus  1  may measure a state of the workpiece W. The state of the workpiece W may include a position of the workpiece W. The position of the workpiece W may include a position of the surface of the workpiece W. The position of the surface of the workpiece W may include a position of each surface part, which is obtained by segmentalizing the surface of the workpiece W, in at least one of the X axis direction, the Y axis direction and the Z axis direction. The state of the workpiece W may include a shape (for example, a three-dimensional shape) of the workpiece W. The shape of the workpiece W may include the shape of the surface of the workpiece W. The shape of the surface of the workpiece W may include a direction of each surface part, which is obtained by segmentalizing the surface of the workpiece W (for example, a direction of a normal line of each surface part, and it is substantially equivalent to an inclined amount of each surface part with respect to at least one of the X axis, the Y axis and the Z axis), in addition to or instead of the above described position of the surface of the workpiece W. The state of the workpiece W may include a size (for example, a size in at least one of the X axis direction, the Y axis direction and the Z axis direction) of the workpiece W. 
     In order to process and measure the workpiece W, the processing apparatus  1  includes a processing light source  11  that is configured to generate the processing light EL, a measurement light source  12  that is configured to generate a measurement light ML, a processing head  13  that is configured to irradiate the workpiece W with the processing light EL from the processing light source  11  and to irradiate the workpiece W with the measurement light ML from the measurement light source  12  and a head driving system  14  that is configured to move the processing head  13 . Furthermore, the processing head  13  includes a processing optical system  131 , a measurement optical system  132 , a combining optical system  133 , a relay optical system  134  and an objective optical system  135 . An optical system including the relay optical system  134  and the objective optical system  135  may be referred to as an irradiation optical system. Note that a configuration of the processing head  13  will be described later in detail by using  FIG.  3   . 
     The processing optical system  131 , the measurement optical system  132  and the combining optical system  133  of the processing head  13  are contained in a head housing  136 . The relay optical system  134  and the objective optical system  135  of the processing head  13  are contained in a head housing  137 . However, the processing optical system  131 , the measurement optical system  132  and the combining optical system  133  may not be contained in the head housing  136 . The relay optical system  134  and the objective optical system  135  may not be contained in the head housing  137   
     The head housing  137  is connected to the head housing  136 . The head housing  137  is coupled with a lower part (namely, the −Z side) of the head housing  136 . The head housing  137  is disposed at a position that is closer to a below described stage  22  (furthermore, the workpiece W placed on the stage  22 ) than the head housing  136  is. The head housing  137  has a shape that allows the head housing  137  to be inserted into a space WSP formed in the workpiece W (specifically, a space WSP surrounded by at least a part of the surface of the workpiece W). In an example illustrated in  FIG.  1   , the cylindrical space WSP that is surrounded by an inner wall surface Wsw extending along the Z axis direction and that extends along the Z axis direction is formed in the workpiece W. In this case, the head housing  137  may have a shape (for example, a cylindrical shape extending along the Z axis direction) that allows the head housing  137  to be inserted into the cylindrical space WSP. The processing head  13  may process and measure the workpiece W in a state where the head housing  137  is inserted into the space WSP of the workpiece W. On the other hand, the head housing  136  connected to an upper part (namely, the +Z side) of the head housing  137  may not be inserted into the space WSP of the workpiece W. 
     The head driving system  14  is configured to move (namely, displace) the processing head  13  under the control of the control apparatus  4 . The head driving system  14  may move the processing head  13  relative to at least one of a surface plate  21  and the stage  22  of the stage apparatus  2  described below (furthermore, relative to the workpiece W placed on the stage  22 ). 
     The head driving system  14  moves the processing head  13  along at least one of the X axis direction, the Y axis direction, the Z axis direction, the θX direction, the θY direction and the θZ direction. Note that moving the processing head  13  along at least one of the θX direction, the θY direction and the θZ direction may be regarded to be equivalent to changing an attitude of the processing head  13  around at least one of the X axis, the Y axis and the Z axis.  FIG.  1    illustrates an example in which the head driving system  14  moves the processing head  13  along each of the X axis direction and the Z axis direction. In this case, the head driving system  14  includes a X slide member  141  that extends along the X axis direction, a X stage member  142  that is connected to the X slide member  141  to be movable along the X slide member  141 , and a Z slide member  143  that is connected to the X stage member  142  and that extends along the Z axis direction, for example. The X slide member  141  is disposed at a support frame  6  that is disposed on the surface plate  21  through a vibration isolator. The support frame  6  may include: a pair of leg members  61  that are disposed on the surface plate  21  through the vibration isolator and that extends along the Z axis direction; and a beam member  62  that extends along the X axis direction and that is disposed on the pair of the leg members  61  so as to connect upper end parts of the pair of the leg members  61 . The X slide member  141  is disposed at the beam member  62 , for example. The processing head  13  (in an example illustrated in  FIG.  1   , the head housing  136  of the processing head  13 ) is connected to the Z slide member  143  to be movable along the Z slide member  143 . When the X stage member  142  moves along the X slide member  141 , the processing head  13  that is connected to the X stage member  142  through the Z slide member  143  moves along the X axis direction. Moreover, the processing head  13  moves along the Z slide member  143 . Thus, the processing head  13  is movable along each of the X axis direction and the Z axis direction. 
     When the processing head  13  moves, a positional relationship between the stage  22  (moreover, the workpiece W placed on the stage  22 ) and the processing head  13  changes. Namely, the processing head  13  moves, a relative position between the processing head  13  and each of the stage  22  and the workpiece W changes. Therefore, moving the processing head  13  is equivalent to changing the positional relationship between the processing head  13  and each of the stage  22  and the workpiece W. Furthermore, when the positional relationship between the processing head  13  and each of the stage  22  and the workpiece W changes, a positional relationship between each optical system (namely, at least one of the processing optical system  131 , the measurement optical system  132 , the combining optical system  133 , the relay optical system  134  and the objective optical system  135 ) of the processing head  13  and each of the stage  22  and the workpiece W changes. Therefore, moving the processing head  13  is equivalent to changing the positional relationship between each optical system of the processing head  13  and each of the stage  22  and the workpiece W. Moving the processing head  13  is equivalent to moving each optical system of the processing head  13 . Furthermore, when the positional relationship between the processing head  13  and each of the stage  22  and the workpiece W changes, an irradiation position of each of the processing light EL and the measurement light ML on the workpiece W changes. Therefore, moving the processing head  13  is equivalent to changing the irradiation position of each of the processing light EL and the measurement light ML on the workpiece W. 
     The stage apparatus  2  includes the surface plate  21 , the stage  22  and a stage driving system  23 . 
     The surface plate  21  is disposed on a button surface of the housing  5  (alternatively, a support surface such as a floor surface on which the housing  5  is placed). The stage  22  is disposed on the surface plate  21 . A non-illustrated vibration isolator that reduces a transmission of vibration from the surface plate  21  to the stage  22  may be disposed between the surface plate  21  and the bottom surface of the housing  5  or the support surface such as the floor surface on which the housing  5  is placed. Furthermore, the above described support frame  6  may be disposed on the surface plate  21 . 
     The workpiece W is placed on the stage  22 . In this case, the stage  22  may not hold the placed workpiece W. Namely, the stage  22  may not add a holding power for holding the workpiece W to the placed workpiece W. Alternatively, the stage  22  may hold the placed workpiece W. Namely, the stage  22  may add the holding power for holding the workpiece W to the placed workpiece W. For example, the stage  22  may hold the workpiece W by vacuum-sucking and/or electrostatically sucking the workpiece W. 
     The stage driving system  23  is configured to move the stage  22  along at least one of the X axis direction, the Y axis direction, the Z axis direction, the θX direction, the θY direction and the θZ direction. Note that moving the stage  22  along at least one of the θX direction, the θY direction and the θZ direction may be regarded to be equivalent to changing an attitude of stage  22  (furthermore, the workpiece W placed on the stage  22 ) around at least one of the X axis, the Y axis and the Z axis.  FIG.  1    illustrates an example in which the stage driving system  23  moves stage  22  along the Y axis direction. In this case, the stage driving system  23  includes a Y slide member  231  that is disposed on the surface plate  21  through a vibration isolator and that extends along the Y axis direction, for example. The stage  22  is connected to the Y slide member  231  to be movable along the Y slide member  231 . As a result, the stage  22  is movable along the Y axis direction. 
     When the stage  22  moves, the positional relationship between the stage  22  (moreover, the workpiece W placed on the stage  22 ) and the processing head  13  changes. Namely, the stage  22  moves, the relative position between the processing head  13  and each of the stage  22  and the workpiece W changes. Therefore, moving the stage  22  is equivalent to changing the positional relationship between the processing head  13  and each of the stage  22  and the workpiece W. Furthermore, when the positional relationship between the processing head  13  and each of the stage  22  and the workpiece W changes, a positional relationship between each optical system of the processing head  13  and each of the stage  22  and the workpiece W changes. Therefore, moving the stage  22  is equivalent to changing the positional relationship between each optical system of the processing head  13  and each of the stage  22  and the workpiece W. Furthermore, when the positional relationship between the processing head  13  and each of the stage  22  and the workpiece W changes, the irradiation position of each of the processing light EL and the measurement light ML on the workpiece W changes. Therefore, moving the stage  22  is equivalent to changing the irradiation position of each of the processing light EL and the measurement light ML on the workpiece W. 
     The measurement apparatus  3  is configured to measure a measurement target object. The measurable target object may include the workpiece W, for example. In this case, the processing system SYS is configured to measure the workpiece W by using the measurement light ML from the processing apparatus  1  and is configured to measure the workpiece W by using the measurement apparatus  3 . The measurement apparatus  3  may measure the stage of the workpiece W (alternatively, any measurement target object different from the workpiece W, the same is applied to the below described description) of the workpiece W. A measured result by the measurement apparatus  3  is used to mainly performing an alignment between the processing head  13  and the workpiece W as described later in detail. In this case, a measurement resolution of the measurement apparatus  3  may be lower than a measurement resolution by using the measurement light ML from the processing apparatus  1 . However, the measurement resolution of the measurement apparatus  3  may be same as or higher than the measurement resolution by using the measurement light ML from the processing apparatus  1 . An imaging apparatus such as a camera and so on is one example of the measurement apparatus  3 . The imaging apparatus may capture an image of the workpiece W itself, and may capture an image of the workpiece W on which a predetermined projection pattern is projected from an illumination apparatus of the measurement apparatus  3 . 
     The measurement apparatus  3  may be disposed at the processing head  13 . In this case, even when the processing head  13  moves, a positional relationship between the processing head  13  and the measurement apparatus  3  does not change. Alternatively, the measurement apparatus  3  may be disposed at a position that is fixed relative to the processing head  13 . A relative positional relationship between the measurement apparatus  3  and the processing head  13  may be an information that is already known to the control apparatus  4 . 
     The control apparatus  4  is configured to control the operation of the processing system SYSa. For example, the control apparatus  4  may control an operation of the processing system SYS (for example, an operation of at least one of the processing apparatus  1 , the stage apparatus  2  and the measurement apparatus  3 ) so that the processing apparatus  1  properly processes the workpiece W. 
     The control apparatus  4  may include an arithmetic apparatus and a storage apparatus. The arithmetic apparatus may include at least one of a CPU (Central Processing Unit) and a GPU (Graphic Processing Unit), for example. The control apparatus  4  serves as an apparatus for controlling the operation of the processing system SYSa by means of the arithmetic apparatus executing a computer program. The computer program is a computer program that allows the control apparatus  4  (for example, the arithmetic apparatus) to execute (namely, to perform) a below described operation that should be executed by the control apparatus  4 . Namely, the computer program is a computer program that allows the control apparatus  4  to function so as to make the processing system SYSa execute the below described operation. The computer program executed by the arithmetic apparatus may be recorded in the storage apparatus (namely, a recording medium) of the control apparatus  4 , or may be recorded in any recording medium (for example, a hard disk or a semiconductor memory) that is built in the control apparatus  4  or that is attachable to the control apparatus  4 . Alternatively, the arithmetic apparatus may download the computer program that should be executed from an apparatus disposed at the outside of the control apparatus  4  through a network interface. 
     The control apparatus  4  may not be disposed in the processing system SYSa. For example, the control apparatus  4  may be disposed at the outside of the processing system SYSa as a server or the like. In this case, the control apparatus  4  may be connected to the processing system SYSa through a wired and/or wireless network (alternatively, a data bus and/or a communication line). In this case, the control apparatus  4  and the processing system SYSa may be configured to transmit and receive various information through the network. Moreover, the control apparatus  4  may be configured to transmit an information such as a command and a control parameter to the processing system SYSa through the network. The processing system SYSa may include a reception apparatus that is configured to receive the information such as the command and the control parameter from the control apparatus  4  through the network. Alternatively, a first control apparatus that is configured to perform a part of the arithmetic processing performed by the control apparatus  4  may be disposed in the processing system SYSa and a second control apparatus that is configured to perform another part of the arithmetic processing performed by the control apparatus  4  may be disposed at an outside of the processing system SYSa. 
     Note that at least one of an optical disc such as n optical disc, a magnetic disc, an optical-magnetic disc, a semiconductor memory such as a USB memory, and another medium that is configured to store the program may be used as the recording medium recording therein the computer program that should be executed by the arithmetic apparatus. The recording medium may include a device that is configured to record the computer program. Furthermore, various arithmetic processing or functions included in the computer program may be realized by a logical processing block that is realized in the control apparatus  4  by means of the control apparatus  4  (namely, a computer) executing the computer program, may be realized by a hardware such as a predetermined gate array (a FPGA, an ASIC) of the control apparatus  4 , or may be realized in a form in which the logical process block and a partial hardware module that realizes an partial element of the hardware are combined. 
     (1-2) Configuration of Processing Head  13   
     Next, with reference to  FIG.  3   , one example of a configuration of the processing head  13  will be described.  FIG.  3    is a cross-sectional view that illustrates one example of the configuration of the processing head  13 . 
     As illustrated in  FIG.  3   , the processing light EL generated by the processing light source  11  enters the processing head  13  through a light transmitting member such as an optical fiber and so on. The processing light source  11  is configured to generate the processing light EL. When the processing light EL is the laser light, the processing light source  11  may include a laser diode, for example. Furthermore, the processing light source  11  may be a light source that is configured to pulsed-oscillate. In this case, the processing light source  11  is configured to generate a pulsed light (for example, a pulsed light having an ON time shorter than pico-seconds) as the processing light EL. 
     The processing optical system  131  is an optical system to which the processing light EL from the processing light source  11  enters. The processing optical system  131  is an optical system that emits, toward the combining optical system  133 , the processing light EL entering the processing optical system  131 . Therefore, the processing optical system  131  is disposed on an optical path of the processing light EL between the processing light source  11  and the combining optical system  133  (furthermore, the relay optical system  134  and the objective optical system  135 ). The workpiece W is irradiated with the processing light EL emitted from the processing optical system  131  through the combining optical system  133 , the relay optical system  134  and the objective optical system  135 . 
     The processing optical system  131  includes a focus adjustment optical system  1311 , a Galvano mirror  1312  and a fθ lens  1313 , for example. 
     The processing light EL from the processing light source  11  enters the focus adjustment optical system  1311 . The focus adjustment optical system  1311  is an optical member that is configured to adjust a light concentration position of the processing light EL (namely, a condensed position of the processing light EL in a propagating direction of the processing light EL). Thus, the focus adjustment optical system  1311  may be referred to as a condensed position change member. The focus adjustment optical system  1311  may include a plurality of lenses that are arranged along the propagating direction of the processing light EL, for example. In this case, the light concentration position of the processing light EL may be changed by moving at least one of the plurality of lenses along its optical axis direction. 
     The processing light EL that has passed through the focus adjustment optical system  1311  enters the Galvano mirror  1312 . The Galvano mirror  1312  changes a direction along which the processing light EL is emitted from the Galvano mirror  1312  (furthermore, a direction along which the processing light EL is emitted from the processing head  13 ) by deflecting the processing light EL (namely, changing an emitting angle of the processing light EL). When the direction along which the processing light EL is emitted from the Galvano mirror  1312  is changed, the direction along which the processing light EL is emitted from the processing head  13  is changed. When the direction along which the processing light EL is emitted from the processing head  13  is changed, an irradiation position of the processing light EL on the surface of the workpiece W is changed. Note that the Galvano mirror  1312  may be referred to as an emitting direction change member. 
     The Galvano mirror  1312  includes a X sweeping mirror  1312 X that is a movable optical member disposed on the optical path of the processing light EL, a X actuator  1312 MX that is configured to move (namely, displace) the X sweeping mirror  1312 X, a Y sweeping mirror  1312 Y that is a movable optical member disposed on the optical path of the processing light EL and a Y actuator  1312 YX that is configured to move (namely, displace) the Y sweeping mirror  1312 Y for example. Each of the X sweeping mirror  1312 X and the Y sweeping mirror  1312 Y is a tilt angle variable mirror an angle of which is variable relative to the optical path of the processing light EL entering each mirror. The X sweeping mirror  1312 X deflects the processing light EL by changing the angle of the X sweeping mirror  1312 X relative to the optical path of the processing light EL by the X actuator  1312 MX. The Y sweeping mirror  1312 Y deflects the processing light EL by changing the angle of the Y sweeping mirror  1312 Y relative to the optical path of the processing light EL by the Y actuator  1312 MY. 
     Incidentally, the processing optical system  131  may include any optical member that is configured to deflect the processing light EL (namely, that is configured to change the direction along which the processing light EL is emitted from the processing head  13 ), in addition to or instead of the Galvano mirror  1312 . A polygonal mirror having a plurality of reflection surfaces angles of which are different from each other is one example of the optical member. The polygonal mirror is rotatable so as to change an incident angle of the processing light EL with respect to one reflection surface in a period during which the one reflection surface is irradiated with the processing light EL and to switch the reflection surface that is irradiated with the processing light EL between the plurality of reflection surfaces. 
     The processing light EL from the Galvano mirror  1312  enters the ID lens  1313 . The fly lens  1313  is an optical system that is configured to emit, toward the combining optical system  133 , the processing light EL from the Galvano mirror  1312 . 
     On the other hand, the measurement light ML generated by the measurement light source  12  enters the processing head  13  through a light transmitting member such as an optical fiber and so on. Specifically, the measurement light ML generated by the measurement light source  12  enters the measurement optical system  132 . The measurement optical system  132  is an optical system that emits, toward the combining optical system  133 , the measurement light ML entering the measurement optical system  132 . Therefore, the measurement optical system  132  is disposed on an optical path of the measurement light ML between the measurement light source  12  and the combining optical system  133  (furthermore, the relay optical system  134  and the objective optical system  135 ). The workpiece W is irradiated with the measurement light ML emitted from the measurement optical system  132  through the combining optical system  133 , the relay optical system  134  and the objective optical system  135 . 
     The measurement optical system  132  includes a beam splitter  1321  (for example, a polarized beam splitter). The beam splitter  1321  emits, toward the combining optical system  133 , the measurement light ML from the measurement light source  12 . In an example illustrated in  FIG.  3   , the measurement light ML from the measurement light source  12  passes through a polarized split surface of the beam splitter  1321  to be emitted toward the combining optical system  133 . On the other hand, as described later, when the workpiece W is irradiated with the measurement light ML through the combining optical system  133 , the relay optical system  134  and the objective optical system  135 , a measurement light RL corresponding to a returned light from the workpiece W that has been irradiated with the measurement light ML enters the measurement optical system  132  through the combining optical system  133 , the relay optical system  134  and the objective optical system  135 . The beam splitter  1321  emits the measurement light RL toward a detection element  1322  of the measurement optical system  132 . In the example illustrated in  FIG.  3   , the measurement light RL is reflected by the polarized split surface of the beam splitter  1321  to enter the detection element  1322 . As a result, the detection element  1322  detects (for example, optically receive) the measurement light RL from the workpiece W. A detected result of the measurement light RL from the workpiece W is outputted to the control apparatus  4 . 
     Both of the processing light EL emitted from the processing optical system  131  and the measurement light ML emitted from the measurement optical system  132  enter the combining optical system  133 . The combining optical system  133  combines he processing light EL emitted from the processing optical system  131  and the measurement light ML emitted from the measurement optical system  132 . Note that an operation for “combining the processing light EL and the measurement light ML” corresponds to an operation for emitting, toward the same direction (specifically, emitting, toward the same relay optical system  134 ), the processing light EL and the measurement light ML entering the combining optical system  133  from different directions. In order to combine the processing light EL and the measurement light ML, the combining optical system  133  includes a beam splitter  1331  (for example, a polarized beam splitter). The beam splitter  1331  emits, toward the relay optical system  134 , the processing light EL and the measurement light ML entering the beam splitter  1331  from different directions. In the example illustrated in  FIG.  3   , the processing light EL entering the beam splitter  1331  passes through a polarized split surface to enter the relay optical system  134 . Moreover, the measurement light ML entering the beam splitter  1331  is reflected by the polarized split surface to enter the relay optical system  134 . 
     Each of the processing light EL and the measurement light ML that has entered the relay optical system  134  enters the objective optical system  135  through the relay optical system  134 . Thus, the relay optical system  134  is disposed on the optical path of the processing light EL between the processing optical system  131  and the objective optical system  135  and is disposed on the optical path of the measurement light ML between the measurement optical system  132  and the objective optical system  135 . The workpiece W is irradiated with each of the processing light EL and the measurement light ML that has entered the objective optical system  135  through the objective optical system  135 . Especially, each of the processing light EL and the measurement light ML that has entered the objective optical system  135  is emitted toward the workpiece W from an terminal optical member  1351  that is located at the most workpiece W side (in the example illustrated in  FIG.  3   , the most −Z side) along the optical paths of the processing light EL and the measurement light ML among a plurality of optical members (especially, a plurality of optical members having a power) included in the objective optical system  135 . An optical characteristic of the relay optical system  134  and the objective optical system  135  will be described with reference to the optical path of the processing light EL illustrated in  FIG.  4   . 
       FIG.  4    is a cross-sectional view that illustrates the optical path of the processing light EL in the processing head  13 . Each of a plurality of dashed lines illustrating the optical path of the processing light EL in  FIG.  4    represents a principal ray of the processing light EL in a situation where an angle of the Galvano mirror  1312  (specifically, an angle of each of the X sweeping mirror  1312 X and the Y sweeping mirror  1312 Y) with respect to the optical path of the processing light EL entering the Galvano mirror  1312  is fixed. Therefore, when the angle of at least one of the X sweeping mirror  1312 X and the Y sweeping mirror  1312 Y with respect to the optical path of the processing light EL is changed, an angle of the principal ray of the processing light EL emitted from the Galvano mirror  1312  with respect to each of an optical axis of the relay optical system  134  and an optical axis of the objective optical system  135  (hereinafter, these optical axes are referred to as an “optical axis AX”) is changed. Thus, the plurality of dashed lines illustrated in  FIG.  4    represents the optical path of the processing light EL that is changed depending on a movement of at least one of the X sweeping mirror  1312 X and the Y sweeping mirror  1312 Y. 
     As illustrated in  FIG.  4   , the processing light EL from the Galvano mirror  1312  enters the fθ lens  1313 . The fθ lens  1313  condenses the processing light EL entering the fθ lens  1313  on an intermediate condensed plane  1313 IP that is a virtual optical plane intersecting with an optical axis of the fθ lens  1313 . The intermediate condensed plane  1313 IP is an optical plane located on the optical pat of the processing light EL between the fθ lens  1313  and the relay optical system  134 . The intermediate condensed plane  1313 IP corresponds to an imaging plane of the fθ lens  1313 . Thus, a condensed spot that is same as (however, its magnification may be different) a condensed spot formed on the surface of the workpiece W by the processing light EL is formed on the intermediate condensed plane  1313 IP. In other words, the fθ lens  1313  serves as an imaging optical member that forms an image of the processing light EL on the intermediate condensed plane  1313 IP. Here, when at least one of the X sweeping mirror  1312 X and the Y sweeping mirror  1312 Y moves, a direction along which the processing light EL is emitted from the Galvano mirror  1312  is changed. When the direction along which the processing light EL is emitted from the Galvano mirror  1312  is changed, the condensed position of the processing light EL on the intermediate condensed plane  1313 IP by the fθ lens  1313  is changed in a direction along the intermediate condensed plane  1313 IP (namely, a direction intersecting with the optical axis of the fθ lens  1313 ). Namely, the condensed spot formed by the processing light EL on the intermediate condensed plane  1313 IP moves. In other words, a position on the intermediate condensed plane  1313 IP through which the processing light EL passes is changed. As a result, the irradiation position of the processing light EL on the surface of the workpiece W (namely, the position of the condensed spot formed by the processing light EL on the surface of the workpiece W) is changed. 
     The processing light EL from the fθ lens  1313  enters the relay optical system  134  through a non-illustrated combining optical system  133 . The relay optical system  134  is an optical system that condenses the processing light EL entering the relay optical system  134  on a condensed plane  134 IP that is a virtual optical plane intersecting with the optical axis AX of the relay optical system  134 . The condensed plane  134 IP corresponds to an imaging plane of the relay optical system  134 . Here, the relay optical system  134  is aligned with respect to the fθ lens  1313  so that an object plane of the relay optical system  134  is coincident with the above described intermediate condensed plane  1313 IP (namely, the image plane of the fθ lens  1313 ). Namely, the relay optical system  134  is aligned with respect to the fθ lens  1313  so that a relationship between the intermediate condensed plane  1313 IP and the condensed plane  1341 IP is an optically conjugate relationship. Thus, the relay optical system  134  serves as an optical system that allows the relationship between the intermediate condensed plane  1313 IP and the condensed plane  1341 IP to be the optically conjugate relationship. 
     The relay optical system  134  is aligned with respect to the objective optical system  135  so that the condensed plane  134 IP is located in a space between the relay optical system  134  and the objective optical system  135 . The relay optical system  134  is aligned with respect to the objective optical system  135  so that the condensed plane  134 IP is located in a space between two optical members of optical members included in the relay optical system  134  and the objective optical system  135 . 
     A condensed spot that is same as (however, its magnification may be different) the condensed spot formed on the surface of the workpiece W by the processing light EL is formed on the condensed plane  134 IP. In other words, the relay optical system  134  serves as an imaging optical member that forms an image of the processing light EL on the condensed plane  134 IP. Thus, when at least one of the X sweeping mirror  1312 X and the Y sweeping mirror  1312 Y moves, the direction along which the processing light EL is emitted from the Galvano mirror  1312  is changed. When the direction along which the processing light EL is emitted from the Galvano mirror  1312  is changed, a position at which the processing light EL is emitted from the relay optical system  134  is changed. When the position at which the processing light EL is emitted from the relay optical system  134  is changed, the condensed position of the processing light EL on the condensed plane  134 IP by the relay optical system  134  is changed in a direction along the condensed plane  134 IP (namely, a direction intersecting with the optical axis AX of the relay optical system  134 ). Namely, the condensed spot formed by the processing light EL on the condensed plane  134 IP moves. In other words, a position on the condensed plane  134 IP through which the processing light EL passes is changed. In this manner, the condensed position of the processing light EL on the condensed plane  1341 P by the relay optical system  134  (namely, a position on the condensed plane  134 IP through which the processing light EL passes) is changed depending on a change of the direction along which the processing light EL is emitted from the Galvano mirror  1312 . As a result, the irradiation position of the processing light EL on the surface of the workpiece W (namely, the position of the condensed spot formed by the processing light EL on the surface of the workpiece W) is changed. 
     The relay optical system  134  may form, on the condensed plane  134 IP, a reduced image of the image formed on the intermediate condensed plane  1313 IP. Namely, the relay optical system  134  may be configured to serve as an imaging optical system having a reduced magnification. However, the relay optical system  134  may form, on the condensed plane  134 IP, a same magnification image of the image formed on the intermediate condensed plane  1313 IP. The relay optical system  134  may form, on the condensed plane  134 IP, an enlarged image of the image formed on the intermediate condensed plane  1313 IP. 
     The processing light EL from the relay optical system  134  enters the objective optical system  135 . Here, a propagating direction of the processing light EL propagated from the relay optical system  134  to the objective optical system  135  changes depending on the position on the condensed plane  134 IP through which the processing light EL passes. Note that the propagating direction of the processing light EL in the present example embodiment means a direction of the principal ray of the processing light EL. Specifically, the propagating direction of the processing light EL propagated from the relay optical system  134  to the objective optical system  135  changes so that an angle between the optical axis AX and a first axis along the propagating direction of the processing light EL that is condensed at a first position of the condensed plane  134 IP is larger than an angle between the optical axis AX and a second axis along the propagating direction of the processing light EL that is condensed at a second position (note that the second position is closer to the optical axis AX than the first position is) of the condensed plane  134 IP. 
     The relay optical system  134  and the objective optical system  135  are disposed so that an exit pupil  134 P of the relay optical system  134  is located at a position that is away from the condensed plane  1341 P toward the relay optical system  134  side (namely, a side opposite to the workpiece W side) and an entrance pupil  135 PP of the objective optical system  135  is located at a position that is away from the condensed plane  134 IP toward the workpiece W side. Note that each of the exit pupil  134 P of the relay optical system  134  and the entrance pupil  135 PP of the objective optical system  135  is typically optically conjugate with a position at which the Galvano mirror  1312  is disposed. 
     The objective optical system  135  condenses the processing light EL entering the objective optical system  135  to irradiate the workpiece W with it. Namely, the objective optical system  135  emits the processing light EL entering the objective optical system  135  toward the workpiece W so that the processing light EL entering the objective optical system  135  is condensed on the workpiece W. A direction along which the processing light EL is emitted from the objective optical system  135  is changed depending on the change of the direction along which the processing light EL is emitted from the above described Galvano mirror  1312 . 
     Especially in the first example embodiment, the objective optical system  135  emits the processing light EL toward the surface of the workpiece W that intersects with a plane perpendicular to the optical axis AX of the objective optical system  135 . For example, as described above, the space WSP surrounded by at least a part of the surface of the workpiece W is formed in the workpiece W in the first example embodiment. In this case, at least a part of the surface of the workpiece W facing the space WSP intersects with the plane perpendicular to the optical axis AX. Thus, the objective optical system  135  may emit the processing light EL toward at least a part of the surface of the workpiece W facing the space WSP formed in the workpiece W. Specifically, as illustrated in  FIG.  5    that is a cross-sectional view illustrating the processing head  13  at least a part of which is inserted into the space WSP formed in the workpiece W, when the space WSP is formed in the workpiece W, the processing head  13  processes the workpiece W in a state where at least a part of the processing head  13  is inserted into the space WSP. In an example illustrated in  FIG.  5   , the at least a part of the head housing  137  in which the relay optical system  134  and the objective optical system  135  are contained is inserted into the space WSP. In this case, at least a part of the head housing  137  is surrounded by at least a part of the surface of the workpiece W facing the space WSP (the inner wall surface Wsw in the example illustrated in  FIG.  5   ). Thus, at least a part of the objective optical system  135  contained in the head housing  137  is surrounded by the inner wall surface Wsw of the workpiece W. As described above, at least a part of the inner wall surface Wsw of the workpiece W surrounding the objective optical system  135  is one example of the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX of the objective optical system  135 . Thus, the objective optical system  135  may emit the processing light EL toward at least a part of the inner wall surface Wsw of the workpiece W. In this case, the processing light EL from the objective optical system  135  is condensed on the inner wall surface Wsw that is concave with respect to the objective optical system  135  (especially, the terminal optical member  1351 ). 
     Incidentally, it is preferable that a size D 1  of the head housing  137  be smaller than a size D 2  of the space WSP in a direction intersecting with a direction (the Z axis direction in the example illustrated in  FIG.  5   ) along which the head housing  137  is inserted into the space WSP, in order to allow at least a part of the head housing  137  to be inserted into the space WSP. For example, the size D 1  of the head housing  137  in the X axis direction may be smaller than the size D 2  of the space WSP in the X axis direction. For example, the size D 1  of the head housing  137  in the Y axis direction may be smaller than the size D 2  of the space WSP in the Y axis direction. For example, the size D 1  of the head housing  137  in one direction along the XY plane may be smaller than the size D 2  of the space WSP in the one direction along the XY plane. 
     On the other hand, the head housing  136  may not be insertable into the space WSP formed in the workpiece W. In this case, the head housing  136  may be disposed at a position that is away from a position surrounded by the inner wall surface Wsw of the workpiece W facing the space WSP toward the processing light source  11  side. The processing optical system  131  (for example, at least one of the focus adjustment optical system  1311 , the Galvano mirror  1312  and the fθ lens  1313 ) contained in the head housing  136  may be disposed at a position that is away from the position surrounded by the inner wall surface Wsw toward the processing light source  11  side. Namely, the processing optical system  131  may be disposed on the optical path of the processing light EL that is away from the position surrounded by the inner wall surface Wsw toward the processing light source  11  side. 
     When the objective optical system  135  emits the processing light EL toward the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX, the objective optical system  135  may have such a projection characteristic that it projects the image of the processing light EL on the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX. An optical system using a projection method different from a central projection method is one example of the optical system having this projection characteristic. At least one of an equidistant projection method, an equisolidangular projection method and an orthogonal projection method is one example of the projection method different from the central projection method. 
     The irradiation position of the processing light EL on the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX is changed by the Galvano mirror  1312  as described above. thus, a driving aspect of the Galvano mirror  1312  may be set in consideration of the projection characteristic of the objective optical system  135  that irradiates the surface of the workpiece W with the processing light EL. Namely, an emitting direction of the processing light EL that is changeable by the Galvano mirror  1312  may be set in consideration of the projection characteristic of the objective optical system  135 . Since the Galvano mirror  1312  is driven by the X actuator  1312 MX and the Y actuator  1312 MY, the X actuator  1312 MX and the Y actuator  1312 MY may move the X sweeping mirror  1312 M and the Y sweeping mirror  1312 Y, respectively, in consideration of the projection characteristic of the objective optical system  135 . 
     When the objective optical system  135  emits the processing light EL toward the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX, the objective optical system  135  may deflect the processing light EL entering the objective optical system  135  so that the processing light EL is farther away from the optical axis AX more as the processing light EL entering the objective optical system  135  propagates more, as illustrated in  FIG.  5   . More specifically, the terminal optical member  1351  of the objective optical system  135  may deflect the processing light EL entering the terminal optical member  1351  so that the processing light EL is farther away from an optical axis of the terminal optical member  1351  (note that the optical axis of the terminal optical member  1351  is typically coincident with the optical axis AX of the objective optical system  135 ) more as the processing light EL entering the terminal optical member  1351  propagates more. 
     When the objective optical system  135  emits the processing light EL toward the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX, the objective optical system  135  may emit the processing light EL toward a direction that makes an angle of 90 degree or more with respect to the optical axis AX, as illustrated in  FIG.  5   . More specifically, the terminal optical member  1351  of the objective optical system  135  may emit the processing light EL toward a direction that makes an angle of 90 degree or more with respect to the optical axis of the terminal optical member  1351  (namely, the optical axis AX), as illustrated in  FIG.  5   . In this case, the irradiation position (see a reference number EP in  FIG.  5   ) on the workpiece W of the processing light EL emitted from the terminal optical member  1351  toward the direction that makes the angle of 90 degree or more with respect to the optical axis AX may be located at a position that is away from an optical surface  1352  of the terminal optical member  1351  at the workpiece W side toward an entrance side of the terminal optical member  1351  in the direction along the optical axis AX. Namely, the irradiation position on the workpiece W of the processing light EL emitted from the terminal optical member  1351  toward the direction that makes the angle of 90 degree or more with respect to the optical axis AX may be located at a position that is away from an optical surface  1352  of the terminal optical member  1351  at the workpiece W side toward the entrance side of the terminal optical member  1351  in the direction along the optical axis AX. 
     In order to allow the objective optical system  135  to emit the processing light EL toward the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX, an optical member that has a meniscus shape in which a convex plane faces toward an exit side of the processing light EL (the −Z side in the example illustrated in  FIG.  4   ) may be used as the terminal optical member  1351 . Specifically, a meniscus lens having a convex plane facing toward the exit side of the processing light EL may be used as the terminal optical member  1351 . Namely, a lens in which a lens surface at the exit side of the processing light EL is a convex surface and a lens surface at the entrance side of the processing light EL (the +Z side in the example illustrated in  FIG.  4   ) is a concave surface may be used as the terminal optical member  1351 . 
     When the objective optical system  135  emits the processing light EL toward the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX, the objective optical system  135  may be aligned with respect to the workpiece W so that the surface of the workpiece W that is irradiated with the processing light EL is disposed to be symmetric with respect to the optical axis AX. For example, in the example illustrated in  FIG.  5   , the objective optical system  135  may be aligned with respect to the workpiece W so that the inner wall surface Wsw of the workpiece W that is irradiated with the processing light EL is disposed to be symmetric (for example, circular-symmetric) with respect to the optical axis AX. In this case, when the objective optical system  135  condenses the processing light EL on a first surface part that is a part of the inner wall surface Wsw, the condensed plane on which the processing light EL is condensed is a plane that is optically conjugate with a second surface part that is another part of the inner wall surface Wsw. Namely, it can be said that the objective optical system  135  forms, at a position of the first surface part that is a part of the surface Wsw of the workpiece W, a conjugate surface that is optically conjugate with a second surface part that is a part of the surface Wsw of the workpiece W that is irradiated with the processing light EL. 
     When this objective optical system  135  is used, the condensed position of the processing light EL emitted from the objective optical system  135  is changed by the Galvano mirror  1312  in a processing shot area EA that is an area on the surface of the workpiece W surrounding the optical axis AX of the objective optical system  135 . Namely, the objective optical system  135  forms the condensed spot of the processing light EL in the processing shot area EA surrounding the optical axis AX. Note that the processing shot area EA corresponds to at least a part of an area that can be irradiated with the processing light EL when the Galvano mirror  1312  deflects the processing light EL while the relative positional relationship between the processing head  13  (especially, the terminal optical member  1351 ) and the workpiece W is fixed. Typically, the processing shot area EA corresponds to an area that is irradiated with the processing light EL that should be actually emitted toward the workpiece W to process the workpiece W when the Galvano mirror  1312  deflects the processing light EL while the relative positional relationship between the processing head  13  (especially, the terminal optical member  1351 ) and the workpiece W is fixed. For example, as illustrated in  FIG.  6 A  and  FIG.  6 B  each of which illustrates one example of the processing shot area EA, the condensed position of the processing light EL from the objective optical system  135  may be changed in the processing shot area EA that corresponds to a part of the cylindrical inner wall surface Wsw of the workpiece W. Namely, the irradiation position of the processing light EL on the surface of the workpiece W may be changed in the processing shot area EA that corresponds to a part of the cylindrical inner wall surface Wsw of the workpiece W. Thus, a shape of a cross-section (for example, a cross-section along the XY plane) of the processing shot area EA including an axis intersecting with the optical axis AX may be same as a shape of a cross-section of the inner wall surface Wsw (namely, a shape of a cross-section of the space WSP) including an axis intersecting with the optical axis AX. In the example illustrated in  FIG.  6 A  and  FIG.  6 B , the shape of the cross-section of the processing shot area EA including the axis intersecting with the optical axis AX is a circular shape in conformity with the shape of the inner wall surface Wsw having the cylindrical shape. Namely, in the example illustrated in  FIG.  6 A  and  FIG.  6 B , since the inner wall surface Wsw has the cylindrical shape, the processing shot area EA is an annular shape. The processing shot area EA is an area facing toward the optical axis AX side (namely, the objective optical system  135  side), because the surface of the workpiece W faces toward the optical axis AX side (namely, the objective optical system  135  side). In this case, it can be said that the objective optical system  135  emits the processing light EL toward the processing shot area EA so as to sweep the processing shot area EA surrounding the objective optical system  135  with the processing light EL. It can be said that the objective optical system  135  emits the processing light EL radially from the objective optical system  135  toward the processing shot area EA that faces toward the objective optical system  135  to surround the objective optical system  135 . It can be said that the direction along which the processing light EL is emitted from the objective optical system  135  is changed by the Galvano mirror  1312  so that the processing shot area EA surrounding the objective optical system  135  is swept with the processing light EL. 
     Next, in addition to the optical path of the processing light EL in the processing head  13  described above, the optical path of the measurement light ML in the processing head  13  will be described with reference to  FIG.  7   . As illustrated in  FIG.  7   , the measurement light ML from the measurement light source  12  enters the relay optical system  134  through the measurement optical system  132 . Note that the dashed line representing the optical path of the measurement light ML in  FIG.  4    conceptionally represents a border of a beam flux that corresponds to an aggregation of light beams forming the measurement light ML. As illustrated in  FIG.  7   , the measurement light ML enters the relay optical system  134  as a collimated light. In this case, the measurement light source  12  may be a surface light source that generates the collimated light. Alternatively, the measurement optical system  132  may include an optical system that converts the measurement light ML generated by the measurement light source  12  into the collimated light. The workpiece W is irradiated with the measurement light ML that has entered the relay optical system  134  through the relay optical system  134  and the objective optical system  135 . Here, since the relay optical system  134  and the objective optical system  135  have the above described optical characteristic, the surface of the workpiece W that intersects with the plane perpendicular to the optical axis AX is irradiated with at least a part of the measurement light ML that has entered the relay optical system  134 . Namely, as illustrated in  FIG.  8    that illustrates an area on the surface of the workpiece W that is irradiated with the measurement light ML from the objective optical system  135 , a measurement shot area MA that is an area on the surface of the workpiece W surrounding the optical axis AX of the objective optical system  135  is irradiated with at least a part of the measurement light ML that has entered the relay optical system  134 . Here, since the measurement light ML enters the relay optical system  134  as the collimated light, whole of the measurement shot area MA is irradiated with at least a part of the measurement light ML that has entered the relay optical system  134  as the collimated light, even when the Galvano mirror  1312  does not deflect the measurement light ML. Therefore, the measurement shot area MA corresponds to at least a part of an area that can be irradiated with the measurement light ML while the relative positional relationship between the processing head  13  (especially, the terminal optical member  1351 ) and the workpiece W is fixed. As a result, the measurement light RL that is optically received by the detection element  1322  of the measurement optical system  132  enters the detection element  1322  as a collimated light including a returned light from whole of the measurement shot area MA. Thus, the detection element  1322  may include a plurality of light reception elements arranged two-dimensionally in order to detect the measurement light RL. Namely, the detection element  1322  may include an imaging element that is configured to two-dimensionally capture an image of the surface of the workpiece W that overlaps with the measurement shot area MA. In this case, the measurement light ML is substantially used as an illumination light for illuminating at least a part of the surface of the workpiece W. 
     (1-3) Operation of Processing System SYSa 
     Next, an operation of the processing system SYSa will be described. The processing system SYSa performs an alignment operation for performing an alignment between the processing head  13  and the workpiece W by using the measured result by the measurement apparatus  3 . Furthermore, the processing system SYSa performs a measurement operation for measuring at least part of the surface of the workpiece W by using the measurement light ML after performing the alignment operation. Furthermore, the processing system SYSa performs a processing operation for processing at least part of the surface of the workpiece W by using the processing light EL after performing the measurement operation. Thus, in the below described description, the alignment operation, the measurement operation and the processing operation will be described in order. Incidentally, in the below described description, the alignment operation, the measurement operation and the processing operation that are performed when the inner wall surface Wsw of the workpiece W in which the cylindrical space WSP illustrated in  FIG.  1    is formed is processed will be described in order. 
     (1-3-1) Alignment Operation 
     Firstly, the alignment operation will be described. In order to perform the alignment operation, the measurement apparatus  3  measures the workpiece W. For example, the measurement apparatus  3  may capture the image of the workpiece W by capturing the image of the workpiece W. As a result, the control apparatus  4  obtains an information related to the state of the workpiece W (especially, the position of the surface of the workpiece W). The information related to the position of the surface of the workpiece W obtained here includes an information related to a position of the surface of the workpiece W relative to the measurement apparatus  3 . Here, since the relative positional relationship between the measurement apparatus  3  and the processing head  13  is fixed, the information related to a position of the surface of the workpiece W relative to the measurement apparatus  3  substantially includes an information related to a position of the surface of the workpiece W relative to the processing head  13 . Thus, the control apparatus  4  is capable of obtaining the information related to the position of the surface of the workpiece W relative to the processing head  13  based on the measured result by the measurement apparatus  3  and an information that is related to the relative positional relationship between the measurement apparatus  3  and the processing head  13  and that is an information already known to the control apparatus  4 . 
     On the other hand, it is difficult for the control apparatus  4  to determine based on only the measured result by the measurement apparatus  3  which part of the workpiece W is measured by the measurement apparatus  3 . Namely, it is difficult for the control apparatus  4  to determine based on only the measured result by the measurement apparatus  3  what is the shape and the attitude of the workpiece W placed on the stage  22 . Thus, the control apparatus  4  determines by using three-dimensional model data and the measured result by the measurement apparatus  3  what is the shape and the attitude of the workpiece W placed on the stage  22 . Namely, the control apparatus  4  obtains an information related to the relative positional relationship between the processing head  13  and the workpiece W by fitting the three-dimensional model data to the measured result by the measurement apparatus  3 . 
     Then, the control apparatus  4  changes the relative positional relationship between the processing head  13  and the workpiece W to a positional relationship that is suitable for starting the below described measurement operation based on the information related to the relative positional relationship between the processing head  13  and the workpiece W. For example, as illustrated in  FIG.  9   , the control apparatus  4  may change the relative positional relationship between the processing head  13  and the workpiece W so that the head housing  137  moves to a position at which it is allowed to be inserted into the space WSP formed in the workpiece W. Specifically, for example, the control apparatus  4  may change the relative positional relationship between the processing head  13  and the workpiece W so that the head housing  137  is located above the space WSP formed in the workpiece W. Note that the relative positional relationship between the processing head  13  and the workpiece W is changeable by at least one of the head driving system  14  and the stage driving system  23  described above. 
     Alternatively, when a marker MK is formed at a position on the workpiece W that is already known to the control apparatus  4  as illustrated in  FIG.  10    that is a top view illustrating one example of the workpiece W, the measurement apparatus  3  may measure the marker MK under the control of the control apparatus  4 . As a result, the control apparatus  4  obtains an information related to a position of the marker MK (namely, an information related to a position of the marker MK relative to the processing head  13 ). Here, since the position of the marker MK is the information already known to the control apparatus  4 , the control apparatus  4  may determine based on the information related to the position of the marker MK what is the shape and the attitude of the workpiece W placed on the stage  22 . Namely, the control apparatus  4  may obtain the information related to the relative positional relationship between the processing head  13  and the workpiece W. Then, the control apparatus  4  changes the relative positional relationship between the processing head  13  and the workpiece W to the positional relationship that is suitable for starting the below described measurement operation based on the information related to the relative positional relationship between the processing head  13  and the workpiece W. 
     (1-3-2) Measurement Operation 
     Next, the measurement operation will be described as illustrated in  FIG.  11    that illustrates the processing head  13  in a period during which the measurement operation is performed, the processing head  13  moves toward the −Z side along the Z axis direction so that the head housing  137  is inserted into the space WSP formed in the workpiece W after the measurement operation is started. Namely, the processing head  13  moves toward the −Z side along the Z axis direction that intersects with a direction connecting two surface parts of the inner wall surface Wsw of the workpiece W facing each other (namely, a direction along the XY plane). For example, the processing head  13  may move toward the −Z side along the Z axis direction that intersects with the Y axis direction connecting a surface part Wsw(−Y) of the inner wall surface Wsw of the workpiece W located at the −Y side and a surface part Wsw(+Y) of the inner wall surface Wsw of the workpiece W located at the +Y side. Although it is not illustrated in the drawings, the processing head  13  moves toward the −Z side along the Z axis direction that intersects with the X axis direction connecting a surface part of the inner wall surface Wsw of the workpiece W located at the −X side and a surface part of the inner wall surface Wsw of the workpiece W located at the +X side. As a result, the head housing  137  is gradually inserted into the space WSP formed in the workpiece W. 
     In at least a part of a period during which the head housing  137  is gradually inserted into the space WSP formed in the workpiece W, the objective optical system  135  emits the measurement light ML toward the measurement shot area MA on the surface (the inner wall surface Wsw here) of the workpiece W. Namely, the objective optical system  135  emits the measurement light ML toward the measurement shot area MA on the inner wall surface Wsw in at least a part of a period during which the processing head  13  moves toward the −Z side along the Z axis direction. The measurement shot area MA moves along with the movement of the processing head  13 . Specifically, when the processing head  13  moves toward the −Z side along the Z axis direction, the measurement shot area MA also moves toward the −Z side along the Z axis direction on the inner wall surface Wsw of the workpiece W. In this case, the objective optical system  135  emits the measurement light ML toward the measurement shot area MA at a timing at which the measurement shot area MA overlaps with a part of the inner wall surface Wsw of the workpiece W that is desired to be measured by the measurement operation. On the other hand, the objective optical system  135  may not emit the measurement light ML toward the measurement shot area MA at a timing at which the measurement shot area MA overlaps with a part of the inner wall surface Wsw of the workpiece W that may not be measured by the measurement operation. Alternatively, the objective optical system  135  may keep emitting the measurement light ML regardless of the position of the measurement shot area MA. The processing head  13  moves toward the −Z side along the Z axis direction until the measurement of the part of the inner wall surface Wsw of the workpiece W that is desired to be measured by the measurement operation is completed. Namely, the head housing  137  keeps being inserted into the space WSP of the workpiece W until the measurement of the part of the inner wall surface Wsw of the workpiece W that is desired to be measured by the measurement operation is completed. The part of the inner wall surface Wsw of the workpiece W that is desired to be measured by the measurement operation typically corresponds to until a part of the inner wall surface Wsw of the workpiece W that is desired to be processed by the processing light EL. As a result, the measurement of the workpiece W is completed. 
     Note that the objective optical system  135  may emit the measurement light ML toward the measurement shot area MA on the inner wall surface Wsw in at least a part of a period during which the head housing  137  is gradually removed from the space WSP formed in the workpiece W. Namely, the objective optical system  135  may emit the measurement light ML toward the measurement shot area MA on the inner wall surface Wsw in at least a part of a period during which the processing head moves toward the +Z side opposite to the −Z side along the Z axis direction. 
     (1-3-3) Processing Operation 
     Next, the processing operation will be described. Due to the above described measurement operation, an information related to the state of the inner wall surface Wsw of the workpiece W that should be processed by the processing light EL is obtained. The control apparatus  4  set a processing condition based on the information related to the state of the inner wall surface Wsw. The processing condition may include a condition related to the processing light EL. The condition related to the processing light EL may include at least one of an intensity of the processing light EL, an irradiation time of the processing light EL and an irradiation timing of the processing light EL. The processing condition may include a condition related to the movement of the processing head  13 . The condition related to the movement of the processing head  13  may include at least one of a moving speed of the processing head  13 , a moving timing of the processing head  13  and a moving distance of the processing head  13 . The processing condition may include a condition related to the movement of the stage  22 . The condition related to the movement of the stage  22  may include at least one of a moving speed of the stage  22 , a moving timing of the stage  22  and a moving distance of the stage  22 . The processing condition may include a condition related to the Galvano mirror  1312 . The condition related to the Galvano mirror  1312  may include at least one of a rotational amount of the X sweeping mirror  1312 X, a rotational speed of the X sweeping mirror  1312 X, a rotational timing of the X sweeping mirror  1312 X, a rotational direction of the X sweeping mirror  1312 X, a rotational amount of the Y sweeping mirror  1312 Y, a rotational speed of the Y sweeping mirror  1312 Y, a rotational timing of the Y sweeping mirror  1312 Y and a rotational direction of the Y sweeping mirror  1312 Y. 
     Then, the control apparatus  4  controls the processing apparatus  1  and the stage apparatus  2  to process the workpiece W (especially, to process the inner wall surface Wsw of the workpiece W) based on the set processing condition. Specifically, as described above, the head housing  137  is keeps being inserted into the space WSP of the workpiece W until the measurement of the part of the inner wall surface Wsw of the workpiece W that is desired to be measured by the measurement operation (namely, the part of the inner wall surface Wsw of the workpiece W that is desired to be processed by the processing light EL) is completed in the measurement operation. Thus, there is no need to insert the head housing  137  into the space WSP of the workpiece W more after the measurement operation is completed. Thus, as illustrated in  FIG.  12    illustrating the processing head  13  in a period during which the processing operation is performed, in the processing operation, the processing head  13  moves toward the +Z side along the Z axis direction so that the head housing  137  is removed (namely, detached) from the space WSP formed in the workpiece W, differently from the measurement operation. Namely, the processing head  13  moves toward the +Z side, which is opposite to the −Z side toward which the processing head  13  moves in the measurement operation, along the Z axis direction that intersects with a direction connecting two surface parts of the inner wall surface Wsw of the workpiece W facing each other (namely, a direction along the XY plane). As a result, the head housing  137  is gradually removed from the space WSP formed in the workpiece W. 
     In at least a part of a period during which the head housing  137  is gradually removed from the space WSP formed in the workpiece W, the objective optical system  135  emits the processing light EL toward the processing shot area EA on the surface (the inner wall surface Wsw here) of the workpiece W. Namely, the objective optical system  135  emits the measurement light ML toward the processing shot area EA on the inner wall surface Wsw in at least a part of a period during which the processing head  13  moves toward the +Z side along the Z axis direction. The processing shot area EA moves along with the movement of the processing head  13 . Specifically, when the processing head  13  moves toward the +Z side along the Z axis direction, the processing shot area EA also moves toward the +Z side along the Z axis direction on the inner wall surface Wsw of the workpiece W. In this case, the objective optical system  135  emits the measurement light ML toward the processing shot area EA at a timing at which the processing shot area EA overlaps with a part of the inner wall surface Wsw of the workpiece W that is desired to be processed by the processing operation. On the other hand, the objective optical system  135  may not emit the measurement light ML toward the measurement shot area MA at a timing at which the processing shot area EA overlaps with a part of the inner wall surface Wsw of the workpiece W that may not be processed by the processing operation. The processing head  13  moves toward the +Z side along the Z axis direction until the processing of the part of the inner wall surface Wsw of the workpiece W that is desired to be processed by the processing operation is completed. Namely, the head housing  137  keeps being removed from the space WSP of the workpiece W until the processing of the part of the inner wall surface Wsw of the workpiece W that is desired to be processed by the processing operation is completed. As a result, the processing of the workpiece W is completed. 
     Polishing the inner wall surface Wsw is one example of the processing of the inner wall surface Wsw by the processing operation. For example,  FIG.  13 A  illustrates the inner wall surface Wsw at which a concavity and convexity exists. In this case, the processing system SYSa may perform the processing operation to smooth the inner wall surface Wsw at which a concavity and convexity exists. For example, the processing system SYSa may perform the processing operation to irradiate a convex part of the inner wall surface Wsw with the processing light EL and not to irradiate a concave part of the inner wall surface Wsw with the processing light EL. As a result, as illustrated in  FIG.  13 B  illustrating the processed inner wall surface Wsw, the inner wall surface Wsw is smoothed compared to that before the processing operation is performed. 
     Forming a riblet structure on the inner wall surface Wsw is another example of the processing of the inner wall surface Wsw by the processing operation. For example, the processing system SYSa may perform the processing operation to form, on the inner wall surface Wsw, the riblet structure in which a plurality of grooves each of which extends along the Z axis direction along which the cylindrical inner wall surface Wsw extends are arranged along a circumferential direction of the inner wall surface Wsw. 
     Note that the objective optical system  135  may emit the processing light EL toward the processing shot area EA on the inner wall surface Wsw in at least a part of the period during which the head housing  137  is gradually inserted into the space WSP formed in the workpiece W. Namely, the objective optical system  135  may emit the measurement light ML toward the processing shot area EA on the inner wall surface Wsw in at least a part of the period during which the processing head moves toward the −Z side opposite to the +Z side along the Z axis direction. However, a through-put of the processing system SYSa improves when the measurement operation is performed in at least a part of the period during which the head housing  137  is gradually inserted into the space WSP and the processing operation is performed in at least a part of the period during which the head housing  137  is gradually removed from the space WSP. This is because a moving distance of the head housing  137  is shorter. 
     (1-4) Technical Effect of Processing System SYSa 
     The above described processing system SYSa is capable of properly processing the workpiece W by using the processing light EL. Furthermore, the processing system SYSa is capable of properly measuring the workpiece W by using the measurement light ML. 
     Especially, the processing system SYSa is capable of measuring and processing the workpiece W having a complicated shape. Specifically, the processing system SYSa is capable of measuring and processing the workpiece W in which the space WSP that is depressed to be surrounded by at least a part of the surface of the workpiece W is formed. For example, the processing system SYSa is capable of measuring and processing the workpiece W having a surface that is concave with respect to the processing head  13  (for example, the above described inner wall surface Wsw facing the space WSP). 
     Moreover, the processing system SYSa may not include the movable member such as the Galvano mirror  1312  and so on near the tip of the processing head  13 . For example, the processing system SYSa may not include the movable member such as the Galvano mirror  1312  and so on in the head housing  137  that is inserted into the space WSP formed in the workpiece W. The processing system SYSa may include the movable member such as the Galvano mirror  1312  and so on in the head housing  136  that may not be inserted into the space WSP. Here, when the movable member such as the Galvano mirror  1312  and so on is disposed near the tip of the processing head  13  (for example, in the head housing  137 ), there is a possibility that a mechanical characteristic of the movable member is restricted. As a result, there is a possibility that an operation of the movable member is restricted. This is because the tip of the processing head  13  is inserted into the space WSP that is possibly narrow and thus the movable member has a design restriction. As a result, there is a possibility that a processing speed of the workpiece W (namely, a through-put for processing the workpiece W) deteriorates due to the restriction of the operation of the movable member. However, in the present example embodiment, the movable member such as the Galvano mirror  1312  and so on may not be disposed near the tip of the processing head  13 , there is a relatively low possibility that the operation of the movable member is restricted. Therefore, there is also a relatively low possibility that the processing speed of the workpiece W (namely, the through-put for processing the workpiece W) deteriorates. As a result, the processing system SYSa is capable of processing the workpiece W relatively rapidly. 
     Moreover, the processing system SYSa measures the workpiece W by detecting the measurement light RL from the workpiece W by using the detection element  1322  including the imaging element that is configured to capture the image of the workpiece W tow-dimensionally. Thus, the processing system SYSa is capable of measuring the area on the surface of the workpiece W, which corresponds to a two-dimensional imaging surface of the imaging element, as a whole 
     (1-5) Other Example of Workpiece W 
     The processing system SYSa may process the workpiece W that is different from the workpiece W in which the cylindrical space WSP extending along the Z axis direction is formed. 
     For example, as illustrated in  FIG.  14    that is a perspective view illustrating another example of the workpiece W, the processing system SYSa may process a workpiece W 1  in which a square tubular space WSP 1  extending along the Z axis direction is formed. In an example illustrated in  FIG.  14   , the square tubular space WSP 1  that is surrounded by the inner wall surface Wsw including an inner wall surface Wsw  11  of the workpiece W facing toward the −Y side, an inner wall surface Wsw 12  of the workpiece W facing toward the −X side, an inner wall surface Wsw 13  of the workpiece W facing toward the +Y side and an inner wall surface Wsw 14  of the workpiece W facing toward the +X side is formed in the workpiece W 1 . In this case, the processing system SYSa may process at least one of the inner wall surfaces Wsw 11  to Wsw 14  in a state where at least a part of the processing head  13  (especially, the head housing  137 ) is inserted into the space WSP 1 . Namely, the processing system SYSa may process the workpiece W 1  by emitting the processing light EL toward at least one of the inner wall surfaces Wsw 11  to Wsw 14  from the objective optical system  135  that may be located between the inner wall surface Wsw 11  and the inner wall surface Wsw 13  and between the inner wall surface Wsw 12  and the inner wall surface Wsw 14 . Moreover, the processing system SYSa may measure at least one of the inner wall surfaces Wsw 11  to Wsw 14  by detecting the measurement light RL from at least one of the inner wall surfaces Wsw 11  to Wsw 14  by the detection element  1322 . 
     However, when a cross-section of the space WSP 1  (namely, a cross-section of the inner wall surface Wsw) is not a circular shape, a distance between the terminal optical member  1351  of the objective optical system  135  and each part of the inner wall surface Wsw 11  varies depending on a position of each part in the inner wall surface Wsw 11 . For example, as illustrated in  FIG.  15    that is a cross-sectional view illustrating a positional relationship between the workpiece W 1  and the objective optical system  135  that is inserted into the space WSP 1  formed in the workpiece W 1 , a distance between the terminal optical member  1351  and a first part P 21  of the inner wall surface Wsw 11  that is located at or near a center of the inner wall surface Wsw 11  in the X axis direction is shorter than a distance between the terminal optical member  1351  and a second part P 22  of the inner wall surface Wsw 11  that is farther away from the center of the inner wall surface Wsw 11  in the X axis direction that the first part P 21  is. A distance between the terminal optical member  1351  and the second part P 22  of the inner wall surface Wsw 11  is shorter than a distance between the terminal optical member  1351  and a third part P 23  of the inner wall surface Wsw 11  that is farther away from the center of the inner wall surface Wsw 11  in the X axis direction that the second part P 22  is. Namely, the distance between the terminal optical member  1351  and each part of the inner wall surface Wsw 11  is longer as each part is farther away from center of the inner wall surface Wsw 11  more. 0 
     When the distance between the terminal optical member  1351  and each part of the inner wall surface Wsw 11  varies, a length of the optical path of the processing light EL between the terminal optical member  1351  and each part of the inner wall surface Wsw 11  varies. As a result, a relative positional relationship between the light concentration position of the processing light EL and each part of the inner wall surface Wsw 11 . Thus, when the light concentration position of the processing light EL is fixed, there is a possibility that one part of the inner wall surface Wsw 11  is irradiated with the processing light EL the light concentration position of which is coincident with the one part, however, another part of the inner wall surface Wsw 11  is irradiated with the processing light EL the light concentration position of which is not coincident with the another part. Namely, there is a possibility that the one part of the inner wall surface Wsw 11  is irradiated with the processing light EL that is properly condensed at the one part, however, the another part of the inner wall surface Wsw 11  is irradiated with the defocused processing light EL. Thus, the focus adjustment optical system  1311  may adjust the light concentration position of the processing light EL based on the irradiation position of the processing light EL on the inner wall surface Wsw 11  so that each part of the inner wall surface Wsw 11  is irradiated with the processing light EL that is properly condensed at each part of the inner wall surface Wsw 11 . Namely, the focus adjustment optical system  1311 , which changes a relative positional relationship between the light concentration position of the processing light EL and each part of the surface of the workpiece W that is irradiated with the processing light EL, may adjust the light concentration position of the processing light EL based on the irradiation position of the processing light EL on the surface of the workpiece W so that each part of the surface of the workpiece W is irradiated with the processing light EL that is properly condensed at each part of the surface of the workpiece W. Specifically, the irradiation position of the processing light EL on the inner wall surface Wsw 11  is changed by the above Galvano mirror  1312 . Thus, focus adjustment optical system  1311  may adjust the light concentration position of the processing light EL in synchronization with the operation of the Galvano mirror  1312 . Note that the change of the irradiation position of the processing light EL on the inner wall surface Wsw 11  appears as the change of the position through which the processing light EL passes on the condensed plane  134 IP of the relay optical system  134 . Thus, it can be said that focus adjustment optical system  1311  adjusts the light concentration position of the processing light EL based on the position through which the processing light EL passes on the condensed plane  134 IP of the relay optical system  134   
     The same is applied to the other inner wall surface Wsw 12  to inner wall surface Wsw 14 . However, its detailed description is omitted for the purpose of reducing a redundant explanation. 
     Even in the example illustrated in  FIG.  14   , the objective optical system  135  may be aligned with respect to the workpiece W so that the surface of the workpiece W that is irradiated with the processing light EL is disposed to be symmetric with respect to the optical axis AX. For example, the objective optical system  135  may be aligned with respect to the workpiece W so that the inner wall surface Wsw 11  to the inner wall surface Wsw 14  are disposed to be symmetric (for example, circular-symmetric) with respect to the optical axis AX. In this case, when the objective optical system  135  condenses the processing light EL on either one of the inner wall surface Wsw 11  to the inner wall surface Wsw 14 , a condensed plane on which the processing light EL is condensed is a plane that is optically conjugate with at least another one of the inner wall surface Wsw  11  to the inner wall surface Wsw 14 . Namely, it can be said that the objective optical system  135  forms a conjugate plane that is optically conjugate with at least one of the plurality of surfaces Wsw of the workpiece W that are irradiated with the processing light EL. 
     For example, as illustrated in  FIG.  16    that is a perspective view illustrating another example of the workpiece W, the processing system SYSa may process a workpiece W 2  in which a space WSP 2  that is between two surfaces facing along one direction and that is opened in a direction intersecting with the one direction is formed. In an example illustrated in  FIG.  16   , the space WSP 2  that is surrounded by the inner wall surface Wsw including an inner wall surface Wsw 21  of the workpiece W facing toward the −X side and an inner wall surface Wsw 22  of the workpiece W facing toward the +X side is formed in the workpiece W 2 . In this case, the processing system SYSa may process at least one of the inner wall surfaces Wsw 21  to Wsw 22  in a state where at least a part of the processing head  13  (especially, the head housing  137 ) is inserted into the space WSP 2 . The processing system SYSa may measure at least one of the inner wall surfaces Wsw 21  to Wsw 22  by detecting the measurement light RL from at least one of the inner wall surfaces Wsw 21  to Wsw 22  by the detection element  1322 . 
     For example, as illustrated in  FIG.  17    that is a perspective view illustrating another example of the workpiece W, the processing system SYSa may process a workpiece W 3  at which a plurality of protrusions are formed. In an example illustrated in  FIG.  17   , the workpiece W 3  is a turbine including a plurality of turbine blades. In this case, the processing system SYSa may process a surface Wsw 3  of the turbine blade (namely, a surface of the protrusion) in a state where at least a part of the processing head  13  (especially, the head housing  137 ) is inserted into a space WSP 3  between adjacent two turbine blades (namely, adjacent two protrusions). The processing system SYSa may measure the surface Wsw 3  of the turbine blade (namely, the surface of the protrusion) by detecting the measurement light RL from the surface Wsw 3  of the turbine blade (namely, the surface of the protrusion). 
     Even in the examples illustrated in  FIG.  14    to  FIG.  17    (furthermore, the example illustrated in  FIG.  1   ), it can be said that the processing system SYSa processes and measures the workpiece W having the surface that is concave with respect to the processing head  13  (especially, the terminal optical member  1351 ). Therefore, the processing system SYSa may process and measure the workpiece W that is different from the workpieces W illustrated in  FIG.  1    and  FIG.  14    to  FIG.  17    and that has the surface concave with respect to the processing head  13  (especially, the terminal optical member  1351 ). 
     Moreover, even in the examples illustrated in  FIG.  14    to  FIG.  17    (furthermore, the example illustrated in  FIG.  1   ), it can be said that the processing system SYSa inserts the objective optical system  135  into a space, which is surrounded by the surface that is concave with respect to the processing head  13  (especially, the terminal optical member  1351 ), along a direction that intersects with a direction connecting at least two surfaces and processes and measures the surface that is concave with respect to the processing head  13  (especially, the terminal optical member  1351 ). In other words, even in the examples illustrated in  FIG.  14    to  FIG.  17    (furthermore, the example illustrated in  FIG.  1   ), it can be said that the processing system SYSa inserts the objective optical system  135  into a space, which is between the at least two surfaces that face each other and that are included in the surface of the workpiece W, along a direction that intersects with a direction connecting at least two surfaces and irradiated the at least two surfaces with the processing light EL from the objective optical system  135 . Therefore, the processing system SYSa may insert the objective optical system  135  into the space, which is surrounded by the surface that is concave with respect to the processing head  13  (especially, the terminal optical member  1351 ) and which is different from the workpieces W illustrated in  FIG.  1    and  FIG.  14    to  FIG.  17   , along the direction that intersects with the direction connecting at least two surfaces and process and measure the surface that is concave with respect to the processing head  13  (especially, the terminal optical member  1351 ). 
     (2) Processing System SYSb in Second Example Embodiment 
     Next, with reference to  FIG.  18   , a processing system SYS in a second example embodiment (in the below described description, the processing system SYS in the second example embodiment is referred to as a “processing system SYSb”) will be described.  FIG.  18    is a system configuration diagram that illustrates a system configuration of the processing system SYSb in the second example embodiment. Note that a detailed description of a component that is same as the already described component is omitted by assigning the same reference sing to it. 
     As illustrated in  FIG.  18   , the processing system SYSb in the second example embodiment is different from the above described processing system SYSa in the first example embodiment in that it includes a processing apparatus  1   b  instead of the processing apparatus  1 . The processing system SYSb is different from the above described processing system SYSa in that it includes an exhaust apparatus  71   b  and a gas supply apparatus  72   b.  Another feature of the processing system SYSb may be same as another feature of the processing system SYSa. 
     The processing apparatus  1   b  is different from the processing apparatus  1  in that it includes a processing head  13   b  instead of the processing head  13 . Another feature of the processing apparatus  1   b  may be same as another feature of the processing apparatus  1 . The processing head  13   b  is different from the processing head  13  in that it includes an exhaust and gas supply member  138   b.  Another feature of the processing head  13   b  may be same as another feature of the processing head  13 . 
     The exhaust and gas supply member  138   b,  the exhaust apparatus  71   b  and the gas supply apparatus  72   b  are used to suck a gas around the objective optical system  135  from a lateral space of the objective optical system  135 . The exhaust and gas supply member  138   b,  the exhaust apparatus  71   b  and the gas supply apparatus  72   b  collects unnecessary substance (for example, fume) generated by the irradiation of the workpiece W with the processing light EL by sucking the gas around the objective optical system  135 . Next, with reference to  FIG.  19   , the exhaust and gas supply member  138   b,  the exhaust apparatus  71   b  and the gas supply apparatus  72   b  will be described.  FIG.  19    is a cross-sectional view that illustrates the exhaust and gas supply member  138   b,  the exhaust apparatus  71   b  and the gas supply apparatus  72   b  that suck the gas around the objective optical system  135  from the lateral space of the objective optical system  135 . 
     As illustrated in  FIG.  19   , the exhaust and gas supply member  138   b  is disposed in the lateral space of the objective optical system  135 . The exhaust and gas supply member  138   b  is disposed around the objective optical system  135 . In this case, the exhaust and gas supply member  138   b  may be disposed to surround the objective optical system  135 . Namely, the exhaust and gas supply member  138   b  may be a member that has a tubular shape and that may contain the objective optical system  135  in a tube. 
     When the objective optical system  135  is contained in the head housing  137 , the exhaust and gas supply member  138   b  is disposed in a lateral space of the head housing  137 . The exhaust and gas supply member  138   b  is disposed around the head housing  137 . In this case, the exhaust and gas supply member  138   b  may be disposed to surround the head housing  137 . Namely, the exhaust and gas supply member  138   b  may be a member that has a tubular shape extending along the Z axis direction along which the head housing  137  extends and that may contain the head housing  137  in a tube. 
     As described above, the objective optical system  135  is inserted into the space WSP formed in the workpiece W. In this case, the exhaust and gas supply member  138   b  is disposed between the workpiece W and the objective optical system  135 . The exhaust and gas supply member  138   b  is disposed between the inner wall surface Wsw of the workpiece W facing the space WSP and the objective optical system  135 . Incidentally, when the objective optical system  135  is contained in the head housing  137 , the exhaust and gas supply member  138   b  is disposed between the workpiece W and the head housing  137  (namely, between the inner wall surface Wsw and the head housing  137 ). 
     An exhaust port  1381   b  is formed at the exhaust and gas supply member  138   b.  The exhaust port  1381   b  is formed at a surface of the exhaust and gas supply member  138   b  facing toward a side opposite to the objective optical system  135  side. The exhaust port  1381   b  is formed at a surface of the exhaust and gas supply member  138   b  that faces toward the workpiece W when the objective optical system  135  is inserted into the space WSP. Thus, when the objective optical system  135  is inserted into the space WSP, the exhaust port  1381   b  faces the workpiece W (especially, the inner wall surface Wsw facing the space WSP). Furthermore, an exhaust pipe  1382   b  is formed in the exhaust and gas supply member  138   b.  The exhaust pipe  1382   b  is connected to the exhaust port  1381   b . The exhaust pipe  1382   b  is further connected to the exhaust apparatus  71   b.  The exhaust apparatus  71   b  sucks the gas around the objective optical system  135  through the exhaust port  1381   b  and the exhaust pipe  1382   b.  For example, the exhaust apparatus  71   b  sucks the gas from a space between the objective optical system  135  and the workpiece W (especially, the inner wall surface Wsw facing the space WSP). For example, the exhaust apparatus  71   b  sucks the gas from a space which the objective optical system  135  faces. As a result, the unnecessary substance existing in these space is collected. Note that the exhaust apparatus  71   b,  the exhaust port  1381   b  and the exhaust pipe  1382   b  may be referred to as a suction apparatus (a suction part), a suction port and a suction pipe. 
     Since the unnecessary substance is generated by the irradiation of the workpiece W with the processing light EL, the exhaust port  1381   b  may be disposed near a generation source of the unnecessary substance (namely, the irradiation position of the processing light EL on the surface of the workpiece W) in order to improve a collection efficiency of the unnecessary substance. For example, since the processing light EL is emitted from the terminal optical member  1351  of the objective optical system  135 , the exhaust port  1381   b  may be formed near the terminal optical member  1351 . Moreover, when the terminal optical member  1351  emits the processing light EL toward the direction that makes the angle of 90 degree or more with respect to the optical axis AX as described above (see  FIG.  5   ), the generation source of the unnecessary substance is located at a position that is away from the optical surface  1352  of the terminal optical member  1351  toward the entrance side of the terminal optical member  1351  in the direction of the optical axis AX. Thus, the exhaust port  1381   b  may be formed at a position that is away from the optical surface  1352  of the terminal optical member  1351  toward the entrance side of the terminal optical member  1351  in the direction of the optical axis AX. Alternatively, the exhaust and gas supply member  138   b  may be aligned with respect to the objective optical system  135  so that the exhaust port  1381   b  is located near the terminal optical member  1351  or the exhaust port  1381   b  is located at a position that is away from the optical surface  1352  of the terminal optical member  1351  toward the entrance side of the terminal optical member  1351  in the direction of the optical axis AX. 
     An gas supply port  1383   b  is formed at the exhaust and gas supply member  138   b.  The gas supply port  1383   b  is formed at a surface of the exhaust and gas supply member  138   b  facing toward a side opposite to the objective optical system  135  side. The gas supply port  1383   b  is formed at a surface of the exhaust and gas supply member  138   b  that faces toward the workpiece W when the objective optical system  135  is inserted into the space WSP. Thus, when the objective optical system  135  is inserted into the space WSP, the gas supply port  1383   b  faces the workpiece W (especially, the inner wall surface Wsw facing the space WSP). Furthermore, an gas supply pipe  1384   b  is formed in the exhaust and gas supply member  138   b.  The gas supply pipe  1384   b  is connected to the gas supply port  1383   b.  The gas supply pipe  1384   b  is further connected to the gas supply apparatus  72   b.  The gas supply apparatus  72   b  supplies the gas around the objective optical system  135  through the gas supply port  1383   b  and the gas supply pipe  1384   b.  Namely, the gas supply apparatus  72   b  supplies the gas to a space between the objective optical system  135  and the workpiece W (especially, the inner wall surface Wsw facing the space WSP) through the gas supply port  1383   b  and the gas supply pipe  1384   b.  As a result, as illustrated in  FIG.  19   , a flow of the gas flowing from the gas supply port  1383   b  to the exhaust port  1381   b  is formed. In this case, for example, the flow of the gas along at least a part of the inner wall surface Wsw of the workpiece W may be formed. For example, the flow of the gas along at least a part of the annular processing shot area EA on the inner wall surface Wsw may be formed. For example, the flow of the gas along at least a part of a side surface of the head housing  137  (alternatively, a side surface of the objective optical system  135  or the terminal optical member  1351 ) may be formed. As a result, the unnecessary substance is collected more efficiently, compared to a case where the flow of the gas is not formed. Furthermore, since the gas is supplied from the gas supply port  1383   b,  there is less possibility that a pressure in a space around the objective optical system  135  is reduced too much even when the gas is sucked through the exhaust port  1381   b.    
     The exhaust port  1381   b  and the gas supply port  1383   b  may be formed so that the exhaust port  1381   b  and the gas supply port  1383   b  are arranged along a direction along the optical axis AX of the objective optical system  135 . In this case, the exhaust port  1381   b  is formed at a position that is closer to the terminal optical member  1351  than the gas supply port  1383   b  is. In this case, there is a higher possibility that the exhaust port  1381   b  is disposed near the generation source of the unnecessary substance. However, the exhaust port  1381   b  is formed at a position that is farther away from the terminal optical member  1351  than the gas supply port  1383   b  is. 
     The exhaust port  1381   b  and the gas supply port  1383   b  may be formed so that the exhaust port  1381   b  and the gas supply port  1383   b  are arranged along a direction surrounding the objective optical system  135  (namely, a circumferential direction). In an example illustrated in  FIG.  19   , the exhaust port  1381   b  and the gas supply port  1383   b  may be formed so that the exhaust port  1381   b  and the gas supply port  1383   b  are arranged around the Z axis. In this case, as illustrated in  FIG.  20    that illustrated another example of the exhaust and gas supply member  138   b,  the exhaust ports  1381   b  and the gas supply ports  1383   b  may be formed so that the exhaust ports  1381   b  and the gas supply ports  1383   b  are alternately arranged around the Z axis. In this case, the unnecessary substance is collected more efficiently. 
     The above described processing system SYSb in the second example embodiment is capable of achieving an effect that is same as the effect achievable by the above described processing system SYSa in the first example embodiment. Furthermore, the processing system SYSb is capable of properly collecting the unnecessary substance generated by the irradiation of the workpiece W with the processing light EL. As a result, there is a relatively low possibility that the unnecessary substance is adhered to the terminal optical member  1351 . Thus, there is a relatively low possibility that the irradiation of at least one of the processing light EL and the measurement light ML through the terminal optical member  1351  is prevented by the unnecessary substance adhered to the terminal optical member  1351 . As a result, there is a relatively low possibility that at least one of the processing of the workpiece W by using the processing light EL and the measurement of the workpiece W by using the measurement light ML is prevented by the unnecessary substance. 
     Note that the gas supply port  1383   b  and the gas supply pipe  1384   b  may not be formed at the exhaust and gas supply member  138   b.  Furthermore, the processing system SYSb may not include the gas supply apparatus  72   b.  Even in this case, the fact remains that the unnecessary substance is collected by the exhaust port  1381   b.    
     The exhaust port  1381   b  and the exhaust pipe  1382   b  may not be formed at the exhaust and gas supply member  138   b.  Furthermore, the processing system SYSb may not include the exhaust apparatus  71   b.  Even in this case, the flow of the gas is formed by the gas supply port  1383   b.  As a result, the flow of the gas formed by the gas supply port  1383   b  reduces a possibility that the unnecessary substance is adhered to the terminal optical member  1351 , compared to a case where the flow of the gas is not formed. Therefore, there is a low possibility to some extent that at least one of the processing of the workpiece W by using the processing light EL and the measurement of the workpiece W by using the measurement light ML is prevented by the unnecessary substance. 
     the fact remains that the unnecessary substance is collected by the exhaust port  1381   b.    
     (3) Processing System SYSc in Third Example Embodiment 
     Next, with reference to  FIG.  23   , a processing system SYS in a third example embodiment (in the below described description, the processing system SYS in the third example embodiment is referred to as a “processing system SYSc”) will be described.  FIG.  21    is a system configuration diagram that illustrates a system configuration of the processing system SYSc in the third example embodiment. Note that a detailed description of a component that is same as the already described component is omitted by assigning the same reference sing to it. 
     As illustrated in  FIG.  21   , the processing system SYSc in the third example embodiment is different from the above described processing system SYSb in the second example embodiment in that it includes a processing apparatus  1   c  instead of the processing apparatus  1   b . Another feature of the processing system SYSc may be same as another feature of the processing system SYSb. The processing apparatus  1   c  is different from the processing apparatus  1   b  in that it includes a processing head  13   c  instead of the processing head  13   b . Another feature of the processing apparatus  1   c  may be same as another feature of the processing apparatus  1   b . The processing head  13   c  is different from the processing head  13   b  in that it includes an objective optical system  135   c  and an exhaust and gas supply member  138   c  instead of the objective optical system  135  and the exhaust and gas supply member  138   b . Another feature of the processing head  13   c  may be same as another feature of the processing head  13   b.  Thus, with reference to  FIG.  22   , the objective optical system  135   c  and the exhaust and gas supply member  138  in the third example embodiment will be described.  FIG.  22    is a cross-sectional view that illustrates the objective optical system  135   c  and the exhaust and gas supply member  138   c  in the third example embodiment. 
     As illustrated in  FIG.  22   , the exhaust and gas supply member  138   c  is different from the exhaust and gas supply member  138   c  in that the gas supply port  1383   b  and the gas supply pipe  1384   b  may not be formed. Another feature of the exhaust and gas supply member  138   c  may be same as another feature of the exhaust and gas supply member  138   b.    
     The objective optical system  135   c  is different from the objective optical system  135  in that it includes a terminal optical member  1351   c  instead of the terminal optical member  1351 . Another feature of the objective optical system  135   c  may be same as another feature of the objective optical system  135 . The terminal optical member  1351   c  is different from the terminal optical member  1351  in that a through-hole  1353  that penetrates the terminal optical member  1351   c  along the optical axis AX is formed. Another feature of the terminal optical member  1351   c  may be same as another feature of the terminal optical member  1351 . 
     The through-hole  1353   c  is used as a gas supply port for supplying the gas around the objective optical system  135   c  by the gas supply apparatus  72   b.  Namely, in the third example embodiment, the gas supply apparatus  72   b  supplies the gas around the objective optical system  135   c  through an inner space in the head housing  137  and the through-hole  1353   c,  as illustrated by a thick solid line in  FIG.  22   . For example, the gas supply apparatus  72   b  may supply the gas to a space which the terminal optical member  1351   c  faces (specifically, at least a part of the space WSP formed in the workpiece W). through the inner space in the head housing  137  and the through-hole  1353   c.  It can be said that the gas supply apparatus  72   b  supplies the gas around the objective optical system  135   c  from a tip of the objective optical system  135   c , because the terminal optical member  1351   c  is located at the tip of the objective optical system  135   c.  As a result, as illustrated in  FIG.  22   , a flow of the gas flowing from the through-hole  1353   c  to the exhaust port  1381   b  is formed. Thus, the unnecessary substance is collected more efficiently, compared to a case where the flow of the gas is not formed. 
     However, as described above, it is preferable that the through-hole  1353   c  does not prevent the emission of the processing light EL toward the surface of the workpiece W, because the terminal optical member  1351   c  is an optical system that emits the processing light EL toward the surface of the workpiece W. Thus, the through-hole  1353   c  is not formed at one part of the terminal optical member  1351   c  through which the processing light EL, which is actually used to process the workpiece W, passes. The through-hole  1353   c  is formed at another part of the terminal optical member  1351   c  through which the processing light EL, which is actually used to process the workpiece W, does not pass. As a result, even when the through-hole  1353   c  is formed in the terminal optical member  1351   c,  the objective optical system  135   c  is capable of properly emitting the processing light EL toward the surface of the workpiece W. Namely, the objective optical system  135   c  is capable of properly irradiating the processing shot area EA on the surface of the workpiece W with the processing light EL. Note that the above described processing shot area EA is irradiated with the processing light EL that is actually used to process the workpiece W, as described above. Thus, it can be said that the through-hole  1353   c  is not formed at one part of the terminal optical member  1351   c  through which the processing light EL, which propagates toward the processing shot area EA on the surface of the workpiece W, passes. Namely, it can be said that the through-hole  1353   c  is not formed at another part of the terminal optical member  1351   c  through which the processing light EL, which does not propagate toward the processing shot area EA on the surface of the workpiece W, passes. Note that the through-hole  1353   c  may be typically formed in an area including an optical axis of the terminal optical member  1351   c  (namely, the optical axis AX). 
     The above described processing system SYSc in the third example embodiment is capable of achieving an effect that is same as the effect achievable by the above described processing system SYSb in the second example embodiment. 
     (4) Processing System SYSd in Fourth Example Embodiment 
     Next, with reference to  FIG.  23   , a processing system SYS in a fourth example embodiment (in the below described description, the processing system SYS in the fourth example embodiment is referred to as a “processing system SYSd”) will be described.  FIG.  23    is a perspective view that conceptionally illustrates an exterior appearance of the processing system SYSd in the fourth example embodiment. 
     As illustrated in  FIG.  23   , the processing system SYSd in the fourth example embodiment is different from the above described processing system SYSa in the first example embodiment in that it includes a distance sensor  8   d.  Another feature of the processing system SYSd may be same as another feature of the processing system SYSa. 
     The distance sensor  8   d  may be disposed at the processing head  13 . In this case, even when the processing head  13  moves, a positional relationship between the processing head  13  and the distance sensor  8   d  does not change. Alternatively, the distance sensor  8   d  may be disposed at a position, wherein a positional relationship between this position and the processing head  13  is fixed. The relative positional relationship between the distance sensor  8   d  and the processing head  13  may be an information that is already known to the control apparatus  4 . 
     The distance sensor  8   d  is configured to measure a distance between the distance sensor  8   d  and the workpiece W. Since the positional relationship between the distance sensor  8   d  and the processing head  13  is fixed, an information related to the distance between the distance sensor  8   d  and the workpiece W may be regarded to be substantially equivalent to an information related to a distance between the processing head  13  and the workpiece W. Namely, it can be said that a measured result by the distance sensor  8   d  includes the information related to the distance between the processing head  13  and the workpiece W. 
     The control apparatus  4  is configured to determine based on the measured result by the distance sensor  8   d  whether or not the distance between the processing head  13  and the workpiece W is shorter than an allowable lower limit value. When it is determined that the distance between the processing head  13  and the workpiece W is shorter than the allowable lower limit value, it is estimated that the processing head  13  may possibly collide with the workpiece W. Thus, in this case, the control apparatus  4  may control the relative positional relationship between the processing head  13  and the workpiece W to prevent the processing head  13  from colliding with the workpiece W. For example, the control apparatus  4  may control the relative positional relationship between the processing head  13  and the workpiece W so that the processing head  13  is farther away from the workpiece W. 
     The above described processing system SYSd in the fourth example embodiment is capable of achieving an effect that is same as the effect achievable by the above described processing system SYSa in the first example embodiment. Furthermore, the processing system SYSd is capable of properly preventing the collision between the processing head  13  and the workpiece W. Especially, the processing system SYSd is capable of properly preventing the collision between the processing head  13  and the workpiece W in a situation where there is a relatively high possibility that the processing head  13  collides with the workpiece W because the processing head  13  is inserted into the space WSP formed in the workpiece W. 
     Note that at least one of the processing system SYSb in the second example embodiment to the processing system SYSc in the third example embodiment described above may include a feature unique to the processing system SYSd in the fourth example embodiment. The feature unique to the processing system SYSd in the fourth example embodiment may include a feature related to the distance sensor  8   d.    
     (5) Processing System SYSe in Fifth Example Embodiment 
     Next, a processing system SYS in a fifth example embodiment (in the below described description, the processing system SYS in the fifth example embodiment is referred to as a “processing system SYSe”) will be described. The processing system SYSe in the fifth example embodiment is different from the above described processing system SYSa in the first example embodiment in that it includes a processing apparatus  1   e  instead of the processing apparatus  1 . Another feature of the processing system SYSe may be same as another feature of the processing system SYSa. The processing apparatus  1   e  is different from the processing apparatus  1  in that it includes a processing head  13   e  instead of the processing head  13 . Another feature of the processing apparatus  1   e  may be same as another feature of the processing apparatus  1 . Thus, next, with reference to  FIG.  24   , the processing head  13   e  in the fifth example embodiment will be described.  FIG.  24    is a cross-sectional view that illustrates a configuration of the processing head  13   e  in the fifth example embodiment. 
     As illustrated in  FIG.  24   , the processing head  13   e  is different from the processing head  13  in that it includes a light shield member  139   e.  Another feature of the processing head  13   e  may be same as another feature of the processing head  13 . 
     The light shield member  139   e  is disposed on a part of the optical path of the processing light EL emitted from the objective optical system  135 . The light shield member  139   e  is disposed on the optical path of the processing light EL that is not actually used to process the workpiece W. As a result, the processing light EL that is not actually used to process the workpiece W is shielded by the light shield member  139   e.  On the other hand, the light shield member  139   e  is not disposed on the optical path of the processing light EL that is actually used to process the workpiece W. As a result, the processing light EL that is actually used to process the workpiece W is not shielded by the light shield member  139   e.    
     As described above, the processing light EL that is actually used to process the workpiece W is typically the processing light EL with which the processing shot area EA on the surface of the workpiece W is irradiated. Thus, the light shield member  139   e  is disposed on the optical path of the processing light EL with which the processing shot area EA is not irradiated (namely, with which the surface of the workpiece W that does not overlap with the processing shot area EA is irradiated). As a result, the processing light EL with which the processing shot area EA is not irradiated (namely, with which the surface of the workpiece W that does not overlap with the processing shot area EA is irradiated) is shielded by the light shield member  139   e.  On the other hand, the light shield member  139   e  is not disposed on the optical path of the processing light EL with which the processing shot area EA is irradiated. As a result, the processing light EL with which the processing shot area EA is irradiated is not shielded by the light shield member  139   e.    
     The above described processing system SYSe in the fifth example embodiment is capable of achieving an effect that is same as the effect achievable by the above described processing system SYSa in the first example embodiment. Furthermore, in the fifth example embodiment, there is a relatively low possibility that an undesired part (namely, a part that should not be irradiated with the processing light EL) of the surface of the workpiece W is erroneously irradiated with the processing light EL. Thus, the processing system SYSe is capable of processing the workpiece W more properly. 
     Note that each of the processing system SYSa in the first example embodiment to the processing system SYSd in the fourth example embodiment described above may control the Galvano mirror  1312  to prevent the undesired part (namely, the part that should not be irradiated with the processing light EL) of the surface of the workpiece W from being erroneously irradiated with the processing light EL. As a result, each of the processing system SYSa to the processing system SYSd that does not include the light shield member  139   e  is also capable of processing the workpiece W more properly, as with the processing system SYSe. 
     Note that at least one of the processing system SYSb in the second example embodiment to the processing system SYSd in the fourth example embodiment described above may include a feature unique to the processing system SYSe in the fifth example embodiment. The feature unique to the processing system SYSe in the fifth example embodiment may include a feature related to the light shield member  139   e.    
     (6) Processing System SYSf in Sixth Example Embodiment 
     Next, with reference to  FIG.  25    and  FIG.  26   , a processing system SYS in a sixth example embodiment (in the below described description, the processing system SYS in the sixth example embodiment is referred to as a “processing system SYSf”) will be described.  FIG.  25    is a perspective view that conceptionally illustrates an exterior appearance of the processing system SYSf in a sixth example embodiment.  FIG.  26    is a system configuration diagram that illustrates a system configuration of the processing system SYSf in the sixth example embodiment. 
     As illustrated in  FIG.  26   , the processing system SYSf in the sixth example embodiment is different from the above described processing system SYSa in the first example embodiment in that it includes a processing apparatus if instead of the processing apparatus  1 . Another feature of the processing system SYSf may be same as another feature of the processing system SYSa. 
     The processing apparatus  1   f  is different from the processing apparatus  1  in that it includes, instead of the processing head  13 , a processing head  13   f  that is configured to process the workpiece W by using the processing light EL and that may not be configured to measure the workpiece W by using the measurement light ML. The processing apparatus  1   f  is different from the processing apparatus  1  in that it includes: a measurement head  15   f  that is configured to measure the workpiece W by using the measurement light ML; and a head driving system  16   f  that is configured to move the measurement head  15   f.  Namely, the processing apparatus lf is different from the processing apparatus  1  in that the head that is configured to process the workpiece W by using the processing light EL is separated from the head that is configured to measure the workpiece W by using the measurement light ML. Another feature of the processing apparatus  1   f  may be same as another feature of the processing apparatus  1 . Next, with reference to  FIG.  27    that is a cross-sectional view illustrating a configuration of the processing head  13   f  and the measurement head  15   f  in addition to  FIG.  25    to  FIG.  26   , the processing apparatus  1   f  that includes the processing head  13   f  and the measurement head  15   f  will be described more. 
     The processing head  13   f  is different from the processing head  13  in that it may not include the measurement optical system  132  and the combining optical system  133 . Thus, the processing light EL from the processing optical system  131  enters the relay optical system  134  without passing through the combining optical system  133 . Another feature of the processing head  13   f  may be same as another feature of the processing head  13 . 
     The measurement head  15   f  includes the measurement optical system  132 , a relay optical system  154   f  and an objective optical system  155   f.  The measurement optical system  132  is contained in a head housing  156   f.  The relay optical system  154   f  and the objective optical system  155   f  are contained in a head housing  157   f.  However, the measurement optical system  132  may not be contained in the head housing  156   f  The relay optical system  154   f  and the objective optical system  155   f  may not be contained in the head housing  157   f.  Note that the head housing  156   f  may have a feature same as that of the above described head housing  136 . The head housing  157   f  may have a feature same as that of the above described head housing  137 . Thus, a detailed description of the head housings  156   f  and  157   f  is omitted. 
     The measurement light ML from the measurement optical system  132  enters the relay optical system  154   f.  The relay optical system  154   f  emits, toward the objective optical system  155   f,  the measurement light ML that has entered the relay optical system  154   f.  The measurement light ML from the relay optical system  154   f  enters the objective optical system  155   f.  The objective optical system  155   f  emits, toward the workpiece W, the measurement light ML that has entered the objective optical system  155   f.  Here, the relay optical system  154   f  and the objective optical system  155   f  may have feature same as those of the relay optical system  134  and the objective optical system  135  described above, respectively. Thus, the measurement head  15   f  is capable of irradiating the workpiece W with the measurement light ML and detecting the measurement light RL from the workpiece W, as with the above described processing head  13 . 
     The head driving system  16   f  moves the measurement head  15   f  along at least one of the X axis direction, the Y axis direction, the Z axis direction, the θX direction, the θY direction and the θZ direction.  FIG.  25    illustrates an example in which the head driving system  16   f  moves the measurement head  15   f  along each of the X axis direction and the Z axis direction. In this case, the head driving system  14  includes a X stage member  162   f  that is connected to the X slide member  141  to be movable along the X slide member  141  and a Z slide member  163   f  that is connected to the X stage member  162   f  and that extends along the Z axis direction, for example. The measurement head  15   f  (in an example illustrated in  FIG.  1   , the head housing  156   f  of the measurement head  150  is connected to the Z slide member  163   f  to be movable along the Z slide member  163   f.  When the X stage member  162   f  moves along the X slide member  141 , the measurement head  15   f  that is connected to the X stage member  162   f  through the Z slide member  163   f  moves along the X axis direction. Moreover, the measurement head  15   f  moves along the Z slide member  163   f.  Thus, the measurement head  15   f  is movable along each of the X axis direction and the Z axis direction. 
     The above described processing system SYSf in the sixth example embodiment is capable of achieving an effect that is same as the effect achievable by the above described processing system SYSa in the first example embodiment. 
     Note that at least one of the processing system SYSb in the second example embodiment to the processing system SYSe in the fifth example embodiment described above may include a feature unique to the processing system SYSf in the sixth example embodiment. The feature unique to the processing system SYSf in the sixth example embodiment may include a feature related to the separation of the processing head  13   f  and the measurement head  15   f.    
     (7) Processing System SYSg in Seventh Example Embodiment 
     Next, with reference to  FIG.  28   , a processing system SYS in a seventh example embodiment (in the below described description, the processing system SYS in the seventh example embodiment is referred to as a “processing system SYSg”) will be described.  FIG.  28    is a system configuration diagram that illustrates a system configuration of the processing system SYSg in the seventh example embodiment. 
     As illustrated in  FIG.  27   , the processing system SYSg in the seventh example embodiment is different from the above described processing system SYSa in the first example embodiment in that it includes a processing apparatus  1   g  instead of the processing apparatus  1 . Another feature of the processing system SYSg may be same as another feature of the processing system SYSa. The processing apparatus  1   g  is different from the processing apparatus  1  in that it includes a processing head  13   g  instead of the processing head  13 . Another feature of the processing apparatus  1   g  may be same as another feature of the processing apparatus  1 . The processing head  13   g  is different from the processing head  13  in that it is configured to perform an additive processing on the workpiece W. Namely, the processing head  13   g  is different from the processing head  13  in that it is configured to form a three-dimensional structural object (namely, a three-dimensional object having a size in each of three-dimensional directions, and a solid object) on the workpiece W. Another feature of the processing head  13   g  may be same as another feature of the processing head  13 . 
     The processing head  13   g  may be configured to form the three-dimensional structural object by a Laser Metal Deposition. Namely, it can be said that the processing system SYSg is a 3D printer that forms an object by using an Additive layer manufacturing technique. Note that the Additive layer manufacturing technique may be referred to as a Rapid Prototyping, a Rapid Manufacturing or an Additive Manufacturing. 
     When the three-dimensional structural object is formed by the Laser Metal Deposition, the processing head  13   g  includes a material nozzle  139   g.  The material nozzle  139   g  is a material supply member (a power supply member) that is configured to supply a build material M to the workpiece W. The material nozzle  139   g  may supply the build material M to the irradiation position of the processing light EL. As a result, a melt pool is formed on the workpiece W by an energy transmitted from the processing light EL and the build material M is molten in the melt pool. Then, when the build material is not irradiated with the processing light EL the molten build material M is solidified. The processing head  13   g  may repeat the same operation to form the three-dimensional structural object formed by the solidified build material M. 
     Note that the processing apparatus  1   g  may include the processing head  13  for performing the removal processing and a processing head for performing the additive processing separately. In this case, the processing head for performing the additive processing may include an irradiation optical system that irradiates the workpiece W with a processing light for the additive processing and the material nozzle  139   g  that supplies the build material to an irradiation position of the processing light for the additive processing. 
     (8) Other Modified Example 
     In the above described description, the inner wall surface Wsw of the workpiece W is vertical (namely, vertical with respect to at least one of the bottom surface of the workpiece W, the X axis and the Y axis). However, as illustrated in  FIG.  29   , the inner wall surface Wsw of the workpiece W may be inclined with respect to the bottom surface of the workpiece W. Alternatively, the inner wall surface Wsw of the workpiece W may be inclined with respect to the gravity direction. In other words, a size or a shape of an upper end of a space surrounded by the inner wall surface Wsw of the workpiece W may be different from a size or a shape of an lower end of this space. 
     In the above described description, the processing apparatus  1  is configured to measure the workpiece W by using the measurement light ML. However, the processing apparatus  1  may not be configured to measure the workpiece W by using the measurement light ML. In this case, the processing apparatus  1  may not include a component related to the measurement of the workpiece W. For example, the processing apparatus  1  may not include the measurement light source  12 , the measurement optical system  132  and the combining optical system  133 . 
     In the above described description, the stage apparatus  2  includes the stage driving system  23 . However, the stage apparatus  2  may not include the stage driving system  23 . Namely, the stage  22  may not be movable. In the above described description, the processing apparatus  1  includes the head driving system  14 . However, the processing apparatus  1  may not include the head driving system  14 . Namely, the processing head  13  may not be movable. 
     In the above described description, the processing apparatus  1  processes the workpiece W by irradiating the workpiece W with the processing light EL. However, the processing apparatus  1  may process the workpiece W by irradiating the workpiece W with any energy beam (this energy beam may be referred to as “a processing beam”) that is different from a light. In this case, the processing apparatus  1  may include a beam irradiation apparatus that is configured to emit any energy beam in addition to or instead of the processing light source  11 . At least one of a charged particle beam, an electromagnetic wave and the like is one example of any energy beam. A least one of an electron beam, an ion beam and the like is one example of the charged particle beam. 
     The features of each example embodiment described above may be appropriately combined with each other. A part of the features of each example embodiment described above may not be used. Moreover, the disclosures of all publications and United States patents related to an apparatus and the like cited in each embodiment described above are incorporated in the disclosures of the present application by reference if it is legally permitted. 
     The present invention is not limited to the above described examples and is allowed to be changed, if desired, without departing from the essence or spirit of the invention which can be read from the claims and the entire specification, and a processing apparatus, which involves such changes, are also intended to be within the technical scope of the present invention. 
     DESCRIPTION OF REFERENCE CODES 
     
         
           1  processing apparatus 
           11  processing light source 
           12  measurement light source 
           13  processing head 
           131  processing optical system 
           132  measurement optical system 
           133  combining optical system 
           134  relay optical system 
           135  objective optical system 
           1351  terminal optical member 
         EL processing light 
         ML measurement light 
         W workpiece 
         SYS processing system