Patent Publication Number: US-9404803-B2

Title: Light measurement device with identifiable detection elements

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional patent application of U.S. application Ser. No. 13/247,089 filed Sep. 28, 2011 which claims priority to Japanese Patent Application No. 2010-241839 filed Oct. 28, 2010 all of which are incorporated by reference herein in their entireties. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present invention relates to a light measurement device provided with a tunable interference filter that extracts, from an incident light, a light with a predetermined wavelength. 
     2. Related Art 
     In the past, an interference filter that makes a pair of reflection coatings face each other and transmits or reflects a light of an incident light, the light with a predetermined wavelength which was intensified by multiple interference by the pair of reflection coatings, has been known (see, for example, JP-A-2009-251105 (Patent Document 1)). 
     In an optical filter apparatus described in Patent Document 1, a pair of substrates are made to face each other, and one of the substrates is provided with a movable section (a first portion) and a diaphragm (a second portion) that holds the movable section in such a way that the movable section can move with respect to the other substrate. On the movable section, one of a pair of reflection coatings (mirrors) is formed, and, on the other substrate, the other reflection coating facing the reflection coating formed on the movable section is formed. In such an optical filter apparatus, a gap dimension between the pair of reflection coatings can be changed by moving the movable section, whereby it is possible to extract a light according to the gap dimension. 
     Incidentally, in Patent Document 1, when the gap between the reflection coatings is changed, the movable section held by the diaphragm is bent toward the other substrate by electrostatic attraction. In this case, the movable section is moved toward the other substrate by bending of the diaphragm, and, at this time, the movable section also bends slightly, which makes the mirror provided on the movable section also bend. This makes it impossible to make the gap dimension between the pair of reflection coatings uniform and allows lights with different wavelengths to pass depending on the position in the reflection coating, causing a reduction in resolution. In this case, when an imaging sensor formed of a plurality of imaging devices is provided so as to face the interference filter, the wavelengths of the lights which enter the imaging devices differ from one another, making it impossible to grasp accurately the amount of light with a wavelength to be detected. 
     SUMMARY 
     An advantage of some aspects of the invention is to provide a light measurement device that can accurately measure the amount of light with a wavelength to be measured. 
     A light measurement device according to an aspect of the invention includes: a tunable interference filter that transmits a light of an incident light, the light intensified by multiple interference; a detecting section that detects the light which has passed through the tunable interference filter; and a control section that measures the intensity of a light with a measurement wavelength, which is an object to be measured, by controlling the tunable interference filter, wherein the tunable interference filter includes a first substrate, a second substrate facing the first substrate, the second substrate being provided with a movable section and a holding section that holds the movable section in such a way that the movable section can move toward the first substrate, a first reflection coating provided on the first substrate, a second reflection coating provided on the movable section, the second reflection coating facing the first reflection coating with a gap left between the second reflection coating and the first reflection coating, and a gap variable section that can change the dimension of the gap based on an input value input from the control section, the detecting section includes a plurality of detecting elements arranged in a two-dimensional array in at least a region facing the first reflection coating and the second reflection coating, and the control section includes a drive control section that makes the gap variable section change the dimension of the gap by outputting the input value to the gap variable section, a storing section that stores correlation data in which the wavelengths of lights received by the detecting elements for the input value input to the gap variable section are recorded, an element identifying section that identifies the detecting element that can receive a light with a wavelength to be measured for the input value input to the gap variable section based on the correlation data, and a light amount obtaining section that obtains the amount of the light with the wavelength to be measured which was detected by the detecting element identified by the element identifying section. 
     Here, the input value differs depending on the configuration of the gap variable section. For example, as the gap variable section, when a configuration is adopted in which a first electrode is provided on the first substrate and a second electrode facing the first electrode is provided on the second substrate and the movable section is moved by electrostatic attraction, the input value is a voltage value which is applied to the first electrode and the second electrode. Moreover, for example, in a configuration in which a gap between the first reflection coating and the second reflection coating is a hermitically sealed space and the gap variable section changes the gap by applying air pressure to the hermitically sealed space, the input value is the air pressure applied to the gap which is the hermitically sealed space or a value for controlling a pump generating the air pressure. 
     In this aspect of the invention, the light measurement device makes the gap variable section of the tunable interference filter change the gap between the first reflection coating and the second reflection coating by making the drive control section input an input value to the gap variable section, and receives a light which has been subjected to multiple interference in the gap and passed through the gap by the detecting section in which a plurality of detecting elements are arranged. At this time, the element identifying section of the light measurement device identifies the detecting element that can receive a light with a wavelength to be measured for the input value input to the gap variable section based on the correlation data stored in the storing section. Then, the light amount obtaining section obtains the amount of the light detected by this detecting element. 
     As a result, even when the second reflection coating on the movable section bends when the movable section is moved by the gap variable section, it is possible to identify the detecting element facing a portion that transmits a light with a wavelength to be measured, the portion of the gap between the first reflection coating and the second reflection coating. Therefore, by obtaining the amount of the light detected by the identified detecting element, it is possible to measure the amount of the light with the wavelength to be measured accurately. 
     In the light measurement device according to the aspect of the invention, it is preferable that the correlation data be set for each of identical wavelength detecting element groups, each being formed of at least one or more detecting elements receiving lights in an identical wavelength region for the input value input to the gap variable section. 
     When the stress balance acting on the holding section holding the movable section is uniform in the tunable interference filter, for example, when the holding section is disposed so as to be symmetric with respect to the center of the movable section, the portions placed on each concentric circle of the movable section are identical in the amount of bending, and the gap intervals between the first reflection coating and the second reflection coating in these portions are identical to one another. Therefore, in this case, lights in an identical wavelength region are received by the detecting elements disposed so as to face gap regions corresponding to each concentric circle. 
     As a result, when the plurality of detecting elements forming the detecting section are grouped into detecting element groups each receiving an identical wavelength region, correlation data for each detecting element group makes it possible to obtain the wavelength of a received light in each detecting element, the light received when a predetermined input value is input to the gap variable section. With such correlation data, as compared to a case, for example, in which correlation data is set for each detecting element, it is possible to reduce the amount of data and thereby perform measurement of the amount of light swiftly. 
     In the light measurement device according to the aspect of the invention, the correlation data may be set for each detecting element. 
     In this aspect of the invention, the correlation data is set for each detecting element. 
     Here, as described earlier, when the stress balance acting on the holding section holding the movable section is uniform in the tunable interference filter, the gap intervals between the first reflection coating and the second reflection coating in the portions placed on each concentric circle with respect to the center of the movable section are identical to one another. However, for example, when a film, an electrode wire, or the like is formed on the holding section or when there is unevenness in etching, variations may occur in the gap intervals even in the portions located on each concentric circle with respect to the center of the movable section. On the other hand, in the aspect of the invention, since the correlation data is set for each detecting element, the element identifying section can more accurately identify the detecting element that can receive a light with a wavelength to be measured, and the light amount obtaining section can more accurately obtain the amount of the light with the wavelength to be measured. 
     In the light measurement device according to the aspect of the invention, it is preferable that the drive control section obtain input values for the light with the wavelength to be measured based on the correlation data and input the obtained input values to the gap variable section while sequentially switching one input value to another. 
     When the amount of light is measured, the drive control section may sequentially switch one input value input to the gap variable section to another in the entire area of a region in which the gap can fluctuate, for example. However, doing so requires many unnecessary measurement values to detect, for example, a particular wavelength to be measured or the amount of light in a particular measurement wavelength region, resulting in a reduction in measurement efficiency. 
     On the other hand, in the aspect of the invention, the drive control section obtains an input value necessary for transmitting a light with a wavelength to be measured based on the correlation data, and inputs the input values thus obtained to the gap variable section while sequentially switching one input value to another. For example, as the correlation data, when an input value necessary for receiving a light with a wavelength λ 1  to be measured by a detecting element a is S 1 , an input value necessary for receiving the light with the wavelength λ 1  to be measured by a detecting element b is S 2 , and an input value necessary for receiving the light with the wavelength λ 1  to be measured by a detecting element c is S 3 , the drive control section inputs the input values S 1 , S 2 , and S 3  to the gap variable section while sequentially switching one input value to another. 
     In such a configuration, when a wavelength to be measured or a wavelength region to be measured, for example, is determined in advance, it is possible to obtain the amount of the light with the wavelength to be measured by minimum driving and thereby perform swift measurement of the amount of light. 
     It is preferable that the light measurement device according to the aspect of the invention include an intensity distribution measuring section that measures the intensity distribution of the light with the wavelength to be measured based on the amount of the light with the wavelength to be measured which was detected by each detecting element and obtained by the light amount obtaining section. 
     In this aspect of the invention, the intensity distribution measuring section measures the intensity distribution of the light with the wavelength to be measured, the light contained in the incident light, based on the light intensity of the wavelength to be measured which was detected by each detecting element and obtained by the light amount obtaining section. 
     That is, since the detecting elements are arranged in an array, it is possible to generate an image in which the positions of pixels correspond to the positions of these detecting elements. Therefore, by expressing the intensity of a light with a wavelength to be measured in each detecting element by using a color, the shade of color, a contour line, or the like, it is possible to obtain an accurate light intensity distribution easily. 
     Moreover, by creating the intensity distribution of each wavelength of an image which has entered the detecting section, it is possible to perform accurate color analysis of each pixel of the image. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements. 
         FIG. 1  is a diagram showing a schematic configuration of an image spectroscopic measurement device of a first embodiment according to the invention. 
         FIG. 2  is a sectional view showing a schematic configuration of a tunable interference filter and a detecting section of the first embodiment. 
         FIG. 3  is a sectional view showing a state in which a voltage is applied between a first electrode and a second electrode in  FIG. 2  and a movable section is bent toward a first substrate. 
         FIG. 4  is a diagram showing an example of correlation data of the first embodiment. 
         FIGS. 5A to 5D  are diagrams showing an identical wavelength detecting element group that can receive a light to be measured for a predetermined voltage value in the first embodiment. 
         FIGS. 6A and 6B  are diagrams showing an example of a light intensity distribution map. 
         FIG. 7  is a flowchart of a spectroscopic measurement device  1  of the first embodiment. 
         FIG. 8  is a diagram showing an example of correlation data in a second embodiment. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     First Embodiment 
     Hereinafter, a first embodiment according to the invention will be described based on the drawings. 
     1. Overall Configuration of Image Spectroscopic Measurement Device 
       FIG. 1  is a diagram showing a schematic configuration of an image spectroscopic measurement device  1  (hereinafter referred to as a spectroscopic measurement device  1 ) of the embodiment according to the invention. 
     The spectroscopic measurement device  1  is a light measurement device according to the invention, and, as shown in  FIG. 1 , includes an optical sensor  3  and a control unit  4  forming a control section according to the invention. The spectroscopic measurement device  1  is a device that takes an image of an object  2  to be measured and measures the light amount distribution characteristics thereof. 
     2. Configuration of Optical Sensor 
     As shown in  FIG. 1 , the optical sensor  3  includes an incidence system  31 , a tunable interference filter  5  according to the invention, a detecting section  32  receiving a light which has passed through the tunable interference filter  5 , and a voltage control circuit  33  changing the wavelength of a light which is made to pass through the tunable interference filter  5 . 
     2-1. Configuration of Incidence System 
     The incidence system  31  is an optical system guiding an incident light from the object  2  to be measured to the tunable interference filter  5 , and is formed of a plurality of lenses and the like. Here, to make the tunable interference filter  5  disperse and transmit a light with a wavelength to be measured, it is necessary to make a light enter the tunable interference filter  5  perpendicularly. Therefore, in the incidence system  31  of this embodiment, a telecentric system is used, and a principal ray from an image of the object  2  to be measured enters a second substrate, which will be described later, of the tunable interference filter  5  so as to be perpendicular to the second substrate. 
     2-2. Configuration of Detecting Section 
       FIG. 2  is a sectional view showing a schematic configuration of the tunable interference filter  5  and the detecting section  32  of this embodiment. 
     As shown in  FIG. 2 , the detecting section  32  includes a plurality of detecting elements  321  arranged in an array. Here, these detecting elements  321  simply have to be arranged in such a way as to fill at least a region facing a first reflection coating  56  and a second reflection coating  57  of the tunable interference filter  5 . The detecting elements  321  are formed of photoelectric conversion elements such as CCD (charge coupled device) elements, and generate an electrical signal according to the amount of the received light and output the signal to the control unit  4 . 
     2-3. Configuration of Tunable Interference Filter 
     As shown in  FIG. 2 , the tunable interference filter  5  includes a first substrate  51  and a second substrate  52 . The two substrates  51  and  52  are each formed of, for example, a material that can transmit alight in a visible light range, such as various kinds of glass including soda glass, crystalline glass, silica glass, lead glass, potassium glass, borosilicate glass, and no alkali glass and quartz. The two substrates  51  and  52  are formed integrally as a result of their bonded surfaces  513  and  523  formed along the outer edge being bonded together by a plasma-polymerized film  53  containing siloxane as a main ingredient, for example. 
     Moreover, between the first substrate  51  and the second substrate  52 , the first reflection coating  56  and the second reflection coating  57  are provided. Here, the first reflection coating  56  is fixed on a surface of the first substrate  51 , the surface facing the second substrate  52 , and the second reflection coating  57  is fixed on a surface of the second substrate  52 , the surface facing the first substrate  51 . Furthermore, the first reflection coating  56  and the second reflection coating  57  are disposed so as to face each other with a gap G left between them. 
     In addition, between the first substrate  51  and the second substrate  52 , an electrostatic actuator  54 , which is a gap variable section according to the invention, for adjusting the dimension of the gap between the first reflection coating  56  and the second reflection coating  57  is provided. The electrostatic actuator  54  is formed of a first electrode  541  provided on the first substrate  51  and a second electrode  542  provided on the second substrate  52 . 
     2-3-1. Configuration of First Substrate 
     The first substrate  51  has an electrode groove  511  and a mirror fixing section  512  which are formed on a surface facing the second substrate  52  by etching. 
     Though not shown in the drawing, the electrode groove  511  is formed into the shape of a ring whose center coincides with a planar central point in a plan view of a filter in which the first substrate  51  is seen from a substrate thickness direction. 
     The mirror fixing section  512  is formed into the shape of a cylinder jutting toward the second substrate  52  on the same axis as the electrode groove  511 . 
     On the bottom face of the electrode groove  511 , the ring-shaped first electrode  541  forming the electrostatic actuator  54  is formed. Moreover, the first electrode  541  has a first electrode wire (not shown) formed toward the periphery of the first substrate  51 , the first electrode wire extending along a wiring groove. The tip of the first electrode wire is connected to the voltage control circuit  33 . 
     Moreover, the first reflection coating  56  is fixed on a surface of the mirror fixing section  512 , the surface facing the second substrate  52 . The first reflection coating  56  may be a dielectric multilayer formed by stacking, for example, SiO 2  and TiO 2  or may be formed of a metal film such as an Ag alloy. Furthermore, the first reflection coating  56  may have a structure in which a dielectric multilayer and a metal film are stacked. 
     A first bonded surface  513  is formed outside the electrode groove  511  of the first substrate  51 . As mentioned earlier, on the first bonded surface  513 , the plasma-polymerized film  53  bonding the first substrate  51  and the second substrate  52  together is formed. 
     2-3-2. Configuration of Second Substrate 
     The second substrate  52  is formed as a result of a surface thereof which does not face the first substrate  51  being processed by etching. The second substrate  52  includes a cylindrical movable section  521  having a substrate central point as the center thereof and a holding section  522  having the same axis as the movable section  521  and holding the movable section  521 . Here, the holding section  522  is formed so as to have the same peripheral radial dimension as the electrode groove  511  of the first substrate  51 . 
     The movable section  521  is formed so as to be thicker than the holding section  522  to prevent bending. 
     The holding section  522  is a diaphragm surrounding the movable section  521 , and is formed so as to have a thickness of 50 μm, for example. Incidentally, in this embodiment, the diaphragm-shaped holding section  522  is shown as an example; however, a structure may be adopted in which, for example, a holding section having a plurality of pairs of beam structures provided in positions which are symmetric with respect to a center of the movable section is provided. 
     On a surface of the holding section  522 , the surface facing the first substrate  51 , the ring-shaped second electrode  542  facing the first electrode  541  with a predetermined space left between them is formed. Here, as described earlier, the second electrode  542  and the first electrode  541  described above form the electrostatic actuator  54 . 
     Moreover, from part of the outer edge of the second electrode  542 , a second electrode wire (not shown) is formed toward the periphery of the second substrate  52 , and the tip of the second electrode is connected to the voltage control circuit  33 . 
     On a surface of the movable section  521 , the surface facing the first substrate  51 , the second reflection coating  57  facing the first reflection coating  56  with a gap left between them is formed. Incidentally, since the configuration of the second reflection coating  57  is the same as the first reflection coating  56 , description thereof will be omitted. 
     2-3-3. Operation of Tunable Interference Filter at the Time of Application of Voltage 
       FIG. 3  is a sectional view showing a state in which a voltage is applied between the first electrode  541  and the second electrode  542  in  FIG. 2  and the movable section  521  is bent toward the first substrate  51 . 
     In an initial state shown in  FIG. 2 , when a drive voltage is applied between the first electrode  541  and the second electrode  542  from the voltage control circuit  33 , the movable section  521  of the second substrate  52  is displaced toward the first substrate  51  by electrostatic attraction as shown in  FIG. 3 . 
     Here, when a space between the first reflection coating  56  and the second reflection coating  57 , the space forming the gap G, is divided into a plurality of partial gap regions Gm (m=0, 1, 2, . . . ) each facing a corresponding one of the detecting elements  321  of the detecting section  32 , the amounts of gap change of the partial gap regions Gm at the time of application of a voltage have different values as shown in  FIG. 3 . 
     That is, when a drive voltage is applied to the electrostatic actuator  54 , the holding section  522  is bent by electrostatic attraction, whereby the movable section  521  is displaced toward the first substrate  51 . Here, although the movable section  521  is formed so as to be thicker than the holding section  522  to prevent bending, the movable section  521  actually bends slightly. As a result, as shown in  FIG. 3 , the dimension between the first reflection coating  56  and the second reflection coating  57  increases with distance from the central point of the movable section  521 , and the partial gap regions have different gap interval values. 
     Here, since the movable section  521  and the holding section  522  are circular in a plan view and have the same axis, the holding section  522  is a diaphragm having a uniform thickness, and the second electrode  542  formed on the holding section  522  is also formed into the shape of a ring having a uniform thickness, the movable section  521  is bent around a central axis O. Therefore, the partial gap regions Gm (for example, partial gap regions G 1  and G 2  in  FIGS. 2 and 3 ) which are away from the central axis by the same distance have the same gap interval. As a result, the wavelengths of lights which travel to the detecting section  32  through the partial gap regions Gm which are away from the central axis O by the same distance are within an identical wavelength region. Incidentally, in the following description, a group of the partial gap regions Gm which are away from the central axis O by the same distance is referred to as an identical gap region group, and, of the plurality of detecting elements  321  forming the detecting section  32 , a group of detecting elements  321  facing the identical gap region group is referred to as an identical wavelength detecting element group. 
     2-4. Configuration of Voltage Control Circuit 
     Under control of the control unit  4 , the voltage control circuit  33  controls the voltage which is applied to the first electrode  541  and the second electrode  542  of the electrostatic actuator  54 . 
     3. Configuration of Control Unit 
     The control unit  4  controls the overall operation of the spectroscopic measurement device  1 . 
     The control unit  4  is a computer formed of a storing section  41 , a CPU (central processing unit)  42 , and the like, and, for example, a general-purpose personal computer, a personal digital assistant, and, in addition to them, a computer for measurement can be used as the control unit  4 . 
     The control unit  4  includes, as software to be executed on the CPU  42 , an element identifying section  421 , a drive control section  422 , a light amount obtaining section  423 , and an intensity distribution measuring section  424 . 
     The storing section  41  stores various program products which are performed on the CPU  42  and various types of data. Moreover, the storing section  41  stores correlation data indicating the wavelength of a transmitted light detected by each detecting element  321  for a drive voltage which is applied to the electrostatic actuator  54 . 
     Here, the correlation data stored in the storing section  41  will be described based on  FIG. 4 . 
       FIG. 4  is a diagram showing an example of the correlation data of this embodiment. 
     Correlation data  60  is data in which the wavelength (the wavelength of lights which pass through an identical gap region group) of lights which are received by an identical wavelength detecting element group for a voltage value (an input value according to the invention) of a drive voltage which is applied to the electrostatic actuator  54  is stored. As shown in  FIG. 4 , the correlation data is set for each identical wavelength detecting element group (each identical gap region group). Here, in  FIG. 4 , the correlation data  60  is depicted as a graph; however, in actuality, a look-up table in which data relating a voltage value and a transmission wavelength to each identical wavelength detecting element group is recorded is stored. Incidentally, what is stored in the storing section  41  is not limited to such a look-up table; for example, the relationship between a voltage value and a transmission wavelength for each identical wavelength detecting element group may be stored as mathematical data. 
     Next, the element identifying section  421 , the drive control section  422 , the light amount obtaining section  423 , and the intensity distribution measuring section  424  which are software to be executed on the CPU  42  will be described. 
     Based on the correlation data  60  stored in the storing section  41 , the element identifying section  421  obtains an identical wavelength detecting element group that can receive a light (a light to be measured) with a wavelength (a wavelength to be measured) which is an object to be measured for a voltage value (an input value) of a drive voltage set by the drive control section  422 . 
     Based on the correlation data  60  stored in the storing section  41 , the drive control section  422  obtains a voltage value at which the light to be measured can be received in each detecting element  321  of the detecting section  32 . For example, in an example shown in  FIG. 4 , when the wavelength to be measured is λ 1 , the drive control section  422  obtains voltage values V 1 , V 2 , V 3 , and V 4 . Then, the drive control section  422  displaces the interval of the gap G of the tunable interference filter  5  by outputting the obtained voltage values V 1 , V 2 , V 3 , and V 4  to the voltage control circuit  33  in order of increasing voltage value, for example, while switching one voltage value to another. 
     The light amount obtaining section  423  obtains the amount of the light to be measured, the light received by each detecting element  321  of the identical wavelength detecting element group obtained by the element identifying section  421  for the voltage value output from the drive control section  422 . 
       FIGS. 5A to 5D  are diagrams showing an identical wavelength detecting element group that can receive a light to be measured for a predetermined voltage value. In  FIGS. 5A to 5D ,  FIG. 5A  shows the position of an identical wavelength detecting element group that can detect the wavelength λ 1  to be measured corresponding to the voltage value V 1  in  FIG. 4 ,  FIG. 5B  shows the position of an identical wavelength detecting element group that can detect the wavelength λ 1  to be measured corresponding to the voltage value V 2  in  FIG. 4 , and  FIG. 5C  shows the position of an identical wavelength detecting element group that can detect the wavelength λ 1  to be measured corresponding to the voltage value V 3  in  FIG. 4 . Moreover,  FIG. 5D  is a diagram showing the result obtained by combining the light amount detection results in the identical wavelength detecting element groups shown in  FIGS. 5A to 5C . Incidentally, the position of an identical wavelength detecting element group that can detect the wavelength λ 1  to be measured corresponding to the voltage value V 4  is not shown in  FIGS. 5A to 5D . 
     The light amount obtaining section  423  obtains the amount of light of the detecting element  321  that can receive the light to be measured for each of the voltage values set and sequentially switched by the drive control section  422  as shown in  FIGS. 5A to 5D . 
       FIGS. 6A and 6B  are diagrams showing an example of a light intensity distribution map. 
     The intensity distribution measuring section  424  creates a light intensity distribution map shown in  FIGS. 6A and 6B  based on the amount of the light to be measured which was detected by each detecting element  321  and obtained by the light amount obtaining section  423 . 
     4. Operation of Spectroscopic Measurement Device 
     Next, based on a flowchart of the spectroscopic measurement device  1  of this embodiment shown in  FIG. 7 , operation of the spectroscopic measurement device  1 , the operation for measurement of the light to be measured, will be described. 
     In the spectroscopic measurement device  1 , a wavelength to be measured, the wavelength of a light to be measured, is first obtained to measure an in-plane light distribution of the light to be measured (step S 1 ). The wavelength to be measured may be obtained by being input by means of an input unit such as a keyboard connected to the control unit  4  of the spectroscopic measurement device  1 , for example, or previously-set wavelengths to be measured may be obtained sequentially. 
     Then, the drive control section  422  of the control unit  4  obtains, from the storing section  41 , a voltage value Vn at which each wavelength detecting element group can receive the wavelength to be measured by setting the wavelength λ 1  to be measured as a target wavelength (step S 2 ). Moreover, at this time, the drive control section  422  also obtains the number of obtained voltage values (a voltage setting maximum number N). 
     Then, the control unit  4  initializes a voltage setting variable n and sets n=1 (step S 3 ). 
     The drive control section  422  then inputs the voltage value Vn to the voltage control circuit  33  as an input value (step S 4 ). As a result, the voltage value Vn is applied to the electrostatic actuator  54  of the tunable interference filter  5 , and the movable section  521  is displaced toward the first substrate  51  by an amount according to the voltage. 
     When the tunable interference filter  5  is driven and a transmitted light is received by the detecting section  32 , the control unit  4  identifies the detecting element  321  that can receive the light to be measured for the voltage value Vn (step S 5 ). 
     Specifically, the element identifying section  421  searches the correlation data  60  stored in the storing section  41  for an identical wavelength detecting element group that can receive a light with the wavelength λ 1  to be measured for the voltage value Vn output from the drive control section  422  to the voltage control circuit  33  in step S 4 , and identifies each detecting element  321  included in the identical wavelength detecting element group. 
     Then, the light amount obtaining section  423  obtains the amount of the light to be measured which was detected by each detecting element  321  identified in step S 5  (step S 6 ). Moreover, the light amount obtaining section  423  stores the obtained amount of light in the storing section  41 . 
     Next, the control unit  4  adds 1 to the voltage setting variable n (step S 7 ), and determines whether or not the voltage setting variable n becomes greater than the voltage setting maximum number N (step S 8 ). 
     Here, if n≦N, the control unit  4  goes back to step S 4 , that is, repeats the processes from steps S 4  to S 8 . 
     Moreover, if the voltage setting variable n is greater than N in step S 8 , the intensity distribution measuring section  424  creates a light intensity distribution map  70  shown in  FIG. 6A  based on the detection result of the amount of the light to be measured which was obtained by the detecting elements  321  and stored in the storing section  41  (step S 9 ). 
     In step S 9 , the intensity distribution measuring section  424  creates the light intensity distribution map  70  having pixels corresponding to the positions of coordinates of the detecting elements  321  arranged in an array. At this time, the intensity distribution measuring section  424  determines the shade of color of each pixel according to the amount of the light to be measured which was received by the detecting element  321  corresponding to each pixel. Here, the light intensity distribution map  70  in which, as a color of each pixel of the intensity distribution measuring section  424 , a color corresponding to the wavelength λ 1  to be measured is used for the light to be measured, for example, may be created, or the light intensity distribution map  70  in which the light intensity is expressed by a gray scale, for example, may be created. In addition, the distribution of the amount of light may be expressed by changing the color or using a contour line according to the amount of light. Moreover, as shown in  FIG. 6B , a light intensity distribution curve  71  indicating the distribution of light intensity along a direction of a straight line may be created. 
     Incidentally, in the above description, an example in which the light intensity distribution of one wavelength λ 1  to be measured is measured and the light intensity distribution map  70  or the light intensity distribution curve  71  of the light intensity distribution thus measured is created has been shown. When the light intensities for a plurality of wavelengths λn are measured, such measurement can be performed by repeating the processes in steps S 2  to S 9  by switching one value of the wavelength λ to be measured to another in step S 1 . For example, when the chromaticity distribution in an image to be measured is measured, steps S 2  to S 9  described above are performed by continuously switching one wavelength λ to be measured to another, whereby it is possible to measure the distribution of the light intensity of each wavelength in a visible light range and, by combining them, it is possible to measure the chromaticity distribution in an image obtained (taken) by the detecting section  32 . 
     5. Effects of First Embodiment 
     As described above, in the spectroscopic measurement device  1  of the first embodiment described above, the element identifying section  421  identifies the detecting element  321  that can receive a light to be measured for a voltage value applied to the electrostatic actuator  54  of the tunable interference filter  5  based on the correlation data  60 , and the light amount obtaining section  423  receives the amount of the light detected by the identified detecting element  321 . As a result, even when the movable section  521  bends due to the driving of the electrostatic actuator  54  and different partial gap regions Gm have different dimensions, it is possible to identify the detecting element  321  that can receive the light to be measured. Since the amount of light is obtained based on the identified detecting element  321 , it is possible to improve the light amount detection accuracy. 
     Moreover, the correlation data  60  is set for each identical wavelength detecting element group. 
     That is, in the tunable interference filter  5  of this embodiment, the movable section  521  is formed into the shape of a cylinder, and the periphery thereof is held by the holding section  522  which is a ring-shaped diaphragm. In such a configuration, if the balance of stress on the diaphragm is uniform, when the movable section  521  is driven by the electrostatic actuator  54 , the partial gap regions Gm which are away from the central axis O by the same distance have the same dimension, and lights in an identical wavelength region pass through the partial gap regions Gm. In such a case, when the correlation data  60  is set for each identical wavelength detecting element group, there is no need to set the correlation data  60  for each detecting element  321 , for example. This makes it possible to reduce the data amount of correlation data  60  stored in the storing section  41 . Moreover, it is possible to perform processing swiftly in such processing as identification of the detecting element  321  by the element identifying section  421  or setting of a voltage value by the drive control section  422  and thereby perform light amount distribution measurement swiftly as a whole. 
     Furthermore, based on the correlation data  60 , the drive control section  422  obtains a voltage value required to receive a wavelength to be measured in each identical wavelength detecting element group, and outputs the voltage values thus obtained to the voltage control circuit  33  while sequentially switching one voltage value to another. 
     In such a configuration, as compared to when, for example, the amount of light is obtained by continuously changing the voltage from a minimum voltage to a maximum voltage that can be set in the electrostatic actuator  54  of the tunable interference filter  5 , it is possible to obtain the amount of light for a wavelength to be measured swiftly. 
     Then, the intensity distribution measuring section  424  creates the light intensity distribution map shown in  FIGS. 6A and 6B  based on the obtained amount of the light to be measured of each detecting element  321 . Creating such a light intensity distribution map allows the user to grasp easily the distribution of the in-plane light intensity of the light to be measured. Moreover, by creating the light intensity distribution map for each wavelength in a visible light range, for example, it is possible to measure the chromaticity distribution of an image to be measured and thereby perform color analysis of the image to be measured accurately. 
     Second Embodiment 
     Next, a second embodiment of the invention will be described based on the drawing. 
       FIG. 8  is a diagram showing an example of correlation data in the second embodiment. Incidentally, in the following description of the second embodiment, the same components as those of the first embodiment described above are identified with the same reference numerals and their descriptions will be omitted. 
     In the first embodiment described above, a configuration in which the correlation data  60  is set for each identical wavelength detecting element group has been described. On the other hand, in the second embodiment, as shown in  FIG. 8 , correlation data  61  is set for each detecting element  321 . 
     Also with such a spectroscopic measurement device, it is possible to perform measurement of light amount distribution by the same processing as that performed in the first embodiment described above in measuring the light amount distribution of a light to be measured. 
     In the spectroscopic measurement device having such correlation data  61 , although the amount of data is increased as compared to the correlation data  60  of the first embodiment, it is possible to perform spectroscopic measurement with a higher degree of accuracy. 
     That is, in the tunable interference filter  5 , due to membrane stress of the second reflection coating  57  provided on the movable section  521 , membrane stress of the second electrode  542 , a position in which the second electrode wire is placed, misalignment caused at the time of production, or the like, the balance of distortion which occurs when the movable section  521  is displaced is sometimes not symmetric with respect to the central axis O. In such a case, even in a group of the partial gap regions Gm which are away from the central axis O by the same distance, the amounts of gap displacement when the movable section  521  is displaced are different from one another. Moreover, even when the partial gap region Ga and the partial gap region Gb have the same dimension at the time of application of, for example, a voltage Vα, the partial gap region Ga and the partial gap region Gb may have different dimensions when another voltage Vβ is applied. 
     In such a case, in the second embodiment, since the correlation data  61  is set for each detecting element  321 , it is possible to identify accurately the detecting element  321  that can receive a light to be measured when a predetermined voltage value Vn is applied to the electrostatic actuator  54 . Thus, the intensity distribution measuring section  424  can create a more accurate light intensity distribution map  70  based on the amount of light detected by the detecting element  321  thus identified, whereby it is possible to improve the measurement accuracy. 
     Other Embodiments 
     It is to be understood that the invention is not limited in any way by the embodiments thereof described above, and, unless modifications and variations depart from the scope of the invention, they should be construed as being included therein. 
     For example, in the first embodiment, an example in which the drive control section  422  obtains, based on the correlation data  60 , a voltage value required to receive a wavelength to be measured in the detecting section  32  and inputs the voltage values thus obtained to the voltage control circuit while sequentially switching one voltage value to another has been shown. On the other hand, when the light intensity distribution of each wavelength in a particular wavelength region such as a certain visible light range, for example, is measured, the drive control section  422  may continuously switch one voltage value which is applied to the electrostatic actuator  54  to another from a settable minimum voltage to a settable maximum voltage, for example. In this case, the amount of light detected by each detecting element  321  when the voltage value is set at each voltage value is stored in the storing section  41 . Then, the light amount obtaining section  423  may obtain the amount of light for a light to be measured by obtaining the amount of light of the detecting element  321  identified by the element identifying section  421  based on the light amount detection result stored in the storing section  41 . 
     Moreover, in the embodiments described above, the electrostatic actuator  54  that displaces the movable section  521  by bending the holding section  522  as a result of a voltage being applied between the first electrode  541  and the second electrode  542  is taken up as an example of a gap variable section; however, the gap variable section is not limited thereto. 
     For example, a configuration using a dielectric actuator in which a first dielectric coil is disposed in place of the first electrode  541  and a second dielectric coil or a permanent magnet is disposed in place of the second electrode may be adopted. For example, in the configuration in which the first dielectric coil and the permanent magnet are provided, a magnetic force is generated by a current which is passed through the first dielectric coil, and the movable section  521  is displaced by an attractive force or a repulsive force generated between the first dielectric coil and the permanent magnet. In such a configuration, as the correlation data  60  and  61 , data that records a transmission wavelength that can be received by each detecting element  321  or each identical wavelength detecting element group for a current value by using a current value which is passed through the first dielectric coil as an input value may be used. 
     Furthermore, a configuration in which a piezoelectric actuator is used in place of the electrostatic actuator  54  may be adopted. In this case, a lower electrode layer, a piezoelectric membrane, and an upper electrode layer are stacked on the holding section  522 , for example, and the holding section  522  is bent by making the piezoelectric membrane expand and contract by changing a voltage which is applied between the lower electrode layer and the upper electrode layer. In such a configuration, as the correlation data  60  and  61 , data that records a transmission wavelength that can be received by each detecting element  321  or each identical wavelength detecting element group for a voltage value by using a voltage value that is applied between the lower electrode layer and the upper electrode layer as an input value may be used. 
     In addition, a configuration in which an actuator using air pressure is used in place of the electrostatic actuator  54  may be adopted. In this case, a space between the first substrate  51  and the second substrate  52  is hermitically sealed, and an air introduction hole introducing air into the hermitically sealed space is provided. Then, the movable section  521  is displaced by a change in the internal pressure by providing, in the air introduction hole, a pump that changes the internal air pressure and changing the air pressure. In such a configuration, as the correlation data  60  and  61 , data which uses the air which is introduced into the hermitically sealed space or let out of the hermitically sealed space as an input value may be used, and, when a motor pump is connected, data which uses electric power for driving the motor pump as an input value may be used. 
     In the embodiments described above, the holding section  522  in the form of a diaphragm has been taken up as an example; however, for example, as described earlier, a configuration may be adopted in which a plurality of beam-shaped holding sections are provided and the movable section  521  is held by these beam-shaped holding sections. In this case, it is preferable to provide the holding sections which are symmetric with respect to the central axis O to make the bending balance of the beam-shaped holding sections uniform. 
     Moreover, in the embodiments described above, an example in which various kinds of lenses forming a telecentric system are used as the incidence system  31  to take an image of the object  2  to be measured with the detecting section  32  has been shown; however, for example, a configuration may be adopted in which an incidence system that converts the light from the object  2  to be measured into a parallel light and makes the parallel light enter the tunable interference filter  5  is incorporated. 
     In addition to the modifications and variations described above, the specific structure and procedure at the time of implementation of the invention can be appropriately changed to another structure etc. unless it departs from the scope of the invention.