Abstract:
Measurement cannot be made when trying to measure a wavefront aberration of a wide-angle lens, being wide in a field of view, comparing to a focus distance, by a Shack-Hartmann sensor, since an inclination of the wavefront exceeds an allowable value of inclination of the Shack-Hartmann sensor. 
     The Shack-Hartmann sensor is inclined at a position of a pupil of a lens, and is controlled so that it lies within the allowable value mentioned above. Photographing is made through step &amp; repeat while overlapping at the same position, to compose in such a manner that overlapping spots are piled up, and thereby measuring the wavefront aberration of the lens having a large pupil diameter.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a wavefront aberration measuring method and a device therefore, for a lens mounted on an optical apparatus, such as, a semiconductor optical inspection apparatus or a printed-circuit board machining apparatus, etc. 
       BACKGROUND ART(S) 
       [0002]    An optical inspection apparatus for a semiconductor wafer is an apparatus for detecting a foreign matter(s) on the wafer, thereby to manage a number of the foreign materials. Because of difference of sizes between the foreign matters to be managed, depending on a manufacturing process of the semiconductor, in the inspection apparatus is provided a function of changing an optical magnification or power. If enlarging the optical power, it is possible to detect the foreign matters, being small much more, on the other hand, a field of view, which can be detected by a sensor, also comes to small, and therefore, throughput goes down to small. Accordingly, on the semiconductor manufacturing line, in particular, limiting to a process or a step necessitating a fine or minute management, an inspection is conducted while enlarging the optical power. A detecting system of the inspection apparatus is built up with an objective lens and an imaging lens, and change of the optical power is carried out, in general, by changing the focus distance of the imaging lens. 
         [0003]    On a line for manufacturing a large amount of wafers is applied plural numbers of optical inspection apparatuses. A permissible value of pieces of the foreign matters is already determined, in advance, on each of the manufacturing processes or steps, and when the number of pieces exceeds that permissible number, then a countermeasure for is taken, for example, cleaning of the apparatus, etc. Herein, if there is difference in sensitivities (i.e., sizes of detectable foreign matters) between an optical inspection apparatuses “A” and “B”, it is necessary to determine or set up the permissible for each optical inspection apparatus; i.e., bringing about a large barrier on the operation thereof. The sensitivity of the optical inspection apparatus depends, largely, upon an imaging capacity of lenses of the detecting system. Accordingly, for the purpose of reducing the sensitivity of the optical inspection apparatus, it is necessary to execute the management of an imaging lens, as a unit, in particular, the management of the wavefront aberration thereof. 
         [0004]    As a method for measuring the wavefront aberration of a lens is already known a method of applying Shack-Hartmann waverfront sensor (hereinafter, “Shack-Hartmann sensor”) therein, as is described in the Patent Document 1 (Japanese Patent Laying-Open No. 2004-14764). The Shack-Hartmann sensor is a sensor for photographing the wavefront (i.e., phase distribution) of lights entering upon the sensor, dividing and condensing that by means of an array lens, in the form of an image of alignment of plural numbers of spots, on a 2-dimensional sensor, and it calculates a wavefront aberration coefficient from the position shift of the spot alignment. 
         [0005]    A method for calculating the wavefront aberration or the wavefront aberration coefficient is already disclosed in the Patent Document 1 (Japanese Patent Laying-Open No. 2004-14764) mentioned above or the Patent Document 2 (Japanese Patent Laying-Open No. 2006-30016). Measurement of the wavefront aberration by means of Shack-Hartmann sensor is advantageous in the following aspects; (1) it is hardly influenced by change of the environment, such as, temperature change of an air within an optical path, or vibrations, etc., (2) it is applicable also to a local change of the wavefront, being equal or larger than the measurement wavelength, which is generated on an spherical lens, etc., comparing to the method by an interferometer, being a main current conventionally. In this prior art, an object of measurement is a projection lens in a photolithography system. On the other hand, the lens of the detection system of the optical inspection apparatus is made up with the objective lens and the imaging lens. 
         [0006]    As was mentioned above, for the purpose of changeability of the optical power, the focus distance of the imaging lens is changed. This may be achieved by exchanging the imaging lens, or applying a zoom lens to it. Although the wavefront aberration can be measured with using the objective lens and the imaging lens as one (1) set, like the projection lens, but there is no knowing that the aberration obtained is a result of cancelling a plus aberration generated on the objective lens by a minus aberration of the imaging lens. In this instance, if changing it to an imaging lens having the different focus distance, there is a possibility that the aberration changes largely. Accordingly, it is preferable to measure the aberration of the objective lens, as a unit. However, since the objective lens, as a unit, forms no image (i.e., an infinite system), it is necessary to adopt other measuring method, having the structure different from that shown in the prior arts mentioned above. 
         [0007]    Also in a laser machining apparatus for use of the printed-circuit board, similar to the objective lens in the optical inspection apparatus for use of the semiconductor, an fθ lens of the indefinite system is applied. In this apparatus, parallel lights are deflected by a galvano-mirror, which is provided at a position of a pupil of the fθ lens, to enter on the fθ lens, and thereby scanning on the printed-circuit board by a condensed light beam. The fθ lens is a lens, being given with distortion thereon, intentionally, so that a beam position is determined on the printed-circuit board by a product fθ of the deflection angle of lights upon the galvano-mirror and the focus distance of the fθ lens. Since also the fθ lens is not the imaging lens, it is necessary to adopt other measuring method, differing from that of the conventional imaging type. In the laser machining apparatus, since the aberration of the fθ lens gives an influence upon a machining configuration at each scanning position of the condensed light beam, for the purpose of obtaining a uniform machining configuration within a region of the scanning, it is necessary to conduct the management upon the aberration (i.e., the wavefront aberration). 
         [0008]    With the wavefront aberration measurement, applying the Shack-Hartmann sensor mentioned above therein, measurement is made on the aberrations, including the aberrations of the lens array of a measurement optical system and/or a relay lens, other than the aberration of the lens, i.e., a measuring object. Then, in the Patent Document 1 (Japanese Patent Laying-Open No. 2004-14764) is disclosed a method for calculating the aberration of the measurement optical system, i.e., by subtracting the data of the lens, i.e., the measuring object, as a unit, from data including the aberration of the measurement optical system, while having conducted the measurement of the lens, i.e., the measuring object, as a unit thereof, with using a separate means, such as, an interferometer, etc. 
         [0009]    On the other hand, in the Patent Document 2 (Japanese Patent Laying-Open No. 2006-30016) is disclosed a method for cancelling the aberration of the measurement optical system therefrom, so as to calculate the aberration of only the lens, i.e., the measuring object; by measuring only the lens, i.e., the measuring object, two (2) times, while changing a posture thereof, such as, rotating, etc., and obtaining a difference for each measurement value. 
       PRIOR ART DOCUMENT (S) 
     Patent Document 
       [0000]    
       
         Patent Document 1: Japanese Patent Laying-Open No. 2004-14764 (2004); and 
         Patent Document 2: Japanese Patent Laying-Open No. 2006-30016 (2006). 
       
     
       BRIEF SUMMARY OF THE INVENTION 
     Problem(s) to be Dissolved by the Invention 
       [0012]    The objective lens of the optical inspection apparatus or the fθ lens of the laser machining apparatus, being mentioned above, is a lens of an infinite system, which cannot form an image by itself as a unit. In  FIG. 12  is shown the structure when measuring the wavefront aberration of the objective lens of the infinite system by means of Shack-Hartmann sensor  4 . The lights condensed at a point “A” by the condenser lens  10  enter onto the objective lens  2 , and after being converted into parallel lights, enter into a pupil (an aperture)  21 , and thereafter they are detected by the Shack-Hartmann sensor  4  in the form of parallel lights, but after being condensed once through a relay lens  300 , which is built up with relay lenses  301  and  302 . 
         [0013]    The relay lens  300 , on the other hand, forms an image of the pupil  21  on the Shack-Hartmann sensor  4 . For the purpose of measuring the wavefront aberration at an end of the field of view, the condenser lens  10  condenses the lights at the point “A” locating at a distance “L” from an optical axis, and this point is determined to be a measuring point for measurement of the wavefront aberration. In this instance, an angle α of the parallel lights  410  entering into the pupil  21  can be presented as follows, with using the focus distance “f 1 ” of the objective lens  410  and the distance “L”: 
         [0000]      tan α= L/f 1  (Eq. 1)
 
         [0014]    On the other hand, a reducing magnification “M” of the relay lens  300  must satisfy the following equation, so that a diameter “Dep” of the pupil can be detected within a detection area “S” of the Shack-Hartmann sensor  4 : 
         [0000]        M&lt;S/Dep   (Eq. 2)
 
         [0015]    Where, the pupil diameter “Dep” is as follows, when presenting an aperture ratio of the objective lens by “NA”. 
         [0000]        Dep= 2 *f 1 *NA   (Eq. 3)
 
         [0016]    In this instance, an angle β entering on the Shack-Hartmann sensor  4  can be obtained by the following equation: 
         [0000]      tan β=tan α/ M   (Eq. 4)
 
         [0017]    Herein, if assuming that the focus distance of the objective lens is 50 mm, “NA” is 0.5, and the distance L at the end of the field of view is 5 mm, respectively, then from the Eq. (3), the pupil diameter comes to Dep=2*50*0.5=50 mm. If assuming that the detection area “S” of the Shack-Hartmann sensor  4  is 15 mm, then from the Eq. (2), the reducing magnification comes to M=15/50=o.3. From the Eq. (1), since tan α=5/50=0.1, an incident or entering angle β on the Shack-Hartmann sensor  4  comes to, at least from the Eq. (4), tan β=0.1/0.3=0.33, and the angle is β=18.4 degrees. 
         [0018]    Herein, explanation will be made on a limit of the incident or entering angle on the Shack-Hartmann sensor  4 , by referring to  FIG. 13 . This  FIG. 13  is a view for showing an inside of the Shack-Hartmann sensor  4 . The wavefront  400  entering on the Shack-Hartmann sensor  4  is divided by the array lens  41 . The light beam  401  entering at the position (λ,η) of the wavefront  400  is condensed at the position, shifting from the position (ξ,η) by ΔX(ξ,η) on a 2-dimensional sensor  42  in accordance with the following equation. 
         [0000]    
       
         
           
             
               
                 
                   
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         [0019]    Herein, “W” means phase distribution, and “f 4 ” the focus distance of the array lens  41 , respectively. 
         [0020]    On the other hand, an inclination θ of measurable wavefront must be nearly equal to or lower than 3 degree, so that the array lens  41  can form an image as a spot on the 2-dimensional sensor  42 . Accordingly, as was mentioned above, if the incident angle upon the Shack-Hartmann sensor  4  comes up to 18.4 degrees, then it dissatisfies the condition of being equal or less than 3 degree, and therefore measurement cannot be made. Namely, with such general method of forming an image of the pupil  21  of the objective lens  2  on the Shack-Hartmann sensor  4  through the relay lens  300 , it is impossible to measure the wavefront aberration of the objective lens  2 . Then, an object of the present invention is to provide a method for measuring the wavefront aberration, clearing the limit of the incident or entering angle onto the Shack-Hartmann sensor  4 , when applying the relay lens therein. 
         [0021]    Next, explanation will be made, relating to other one problem to be dissolved. According to the Patent Document 2 (Japanese Patent Laying-Open No. 2006-30016), though it relates to the method for obtaining the difference of the position shift of an object on the Shack-Hartmann sensor  4 , by making the measurement thereof two (2) times while rotating by 90 degree, for example; however, in case where the object is an aberration, being rotationally symmetric, such as, a spherical aberration, for example, the difference comes to zero (0), i.e., it is impossible to calculate the aberration. Therefore, another object of the present invention is to provided a measuring method for enabling correction of the aberration in the measurement optical system, even for the aberration rotationally symmetric. 
       Means for Dissolving the Problem(s) 
       [0022]    For accomplishing the object mentioned above, according to the present invention, there is adopted the structure of disposing the Shack-Hartmann sensor at the position of the pupil of the objective lens, directly, without providing the relay lens. With this, it is possible to reduce an incident angle upon the Shack-Hartmann sensor. However, as was mentioned above, since it cannot be disposed to be equal to or less than 3 degrees, being as an allowable value, the Shack-Hartmann sensor is inclined in an inclination angle of the wavefront. With this, it is possible to clear away or remove such a limit that the inclination angle upon the Shack-Hartmann sensor should be equal to or less than 3 degrees. 
         [0023]    Also, since the pupil diameter exceeds the field of view for detection of the 2-dimensional sensor within the Shack-Hartmann sensor, it is possible to cover an entire area or region of the pupil diameter, by scanning the Shack-Hartmann sensor. As a method for scanning the Shack-Hartmann sensor, there are provided a method for scanning the 2-dimensional sensor through step &amp; repeat, in a 2-dimensional manner, and also a method for scanning it, in a 1-dimensional manner, the pupil diameter by the 1-dimensional sensor covering the pupil diameter. 
         [0024]    In the former, since pitching and yawing of the scanning stage gives an ill influence upon an error of the position of a spot light condensed when composing an entire area or region of the pupil, there is applied a method of measuring the pitching and yawing of the scanning stage by a 3-axis laser measuring apparatus or an auto-collimator, and thereby correcting or compensating the error. In the latter, since a shift of pitching and yawing of the scanning stage result into an error, there is applied a method of measuring them by a 2-dimensional laser measuring apparatus, thereby correcting or compensating the error. With applying those methods therein, it is possible to measure the wavefront aberration on the entire area or region of the sensor exceeding the field of view for detection thereof. 
         [0025]    Within other invention for clearing away or removing the limit of the incident angle upon the Shack-Hartmann sensor, the incident angle β upon the Shack-Hartmann sensor is always determined to zero (0), by correcting or compensating an inclination of the wavefront at the position of pupil, which is generated at an end of the field of view, by a galvano-mirror disposed at the position of the pupil. With this, it is possible to clear away or remove the limitation of the incident angle, even when forming an image of the pupil, while reducing it within the field of view of the sensor by a relay lens. 
         [0026]    As an invention for measuring an aberration of a measuring optical system, data is measured on a position shift of the spot light due to the aberration of the Shack-Hartmann sensor itself, by measuring a spherical wave generating at a point light source is measured by the, directly, without applying other optical system, and this data is subtracted from data when measuring an objective lens. With this, it is possible to calculate the wavefront aberration of only the objective lens, and also to measure the wavefront aberration, being rotationally symmetric, which cannot be measured by the conventional example. 
       Effect(s) of the Invention 
       [0027]    According to the present invention, since it is possible to make the incident or entering angle onto the Shack-Hartmann sensor small, it is possible to make the measure of the wavefront aberration on the objective lens of the infinite system, by means of the Shack-Hartmann sensor, and therefore achieving the measurement, which is hardly influenced by the environment, comparing to that of the conventional interferometer, etc. And, it is also possible to make the measurement of the wavefront aberration, at high accuracy, only upon the lens as an object of measurement, by measuring the wavefront aberration of the Shack-Hartmann sensor itself, directly, with using a point-like light source. 
         [0028]    With management of the wavefront aberration of the lens, by such means as was mentioned above, the sensitivity of detecting the foreign matter(s) and/or the machining configuration of the semiconductor optical inspection apparatus or the laser machining apparatus for the printed-circuit board can be uniformed, and therefore there can be obtain effects, such as, increasing an efficiency of operating plural numbers of the optical inspection apparatuses in the semiconductor manufacturing line, and improving the quality of the laser machining. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]      FIG. 1  is a front cross-sectional view for showing an outlook structure of a wavefront aberration measuring device, according to a first embodiment; 
           [0030]      FIGS. 2A to 2E  are plane views for showing a manner of photographing by a 2-dimensional sensor on a pupil of an objective lens, in the first embodiment; 
           [0031]      FIG. 3  is a plane view of the pupil for showing a rotation stage  22 , on which the objective lens  2  is mounted, and a focusing point “A”; 
           [0032]      FIG. 4  is a front cross-sectional view for showing an outlook structure of the wavefront aberration measuring device, when measuring an aberration of an array lens; 
           [0033]      FIG. 5  is a front cross-sectional view for showing an outlook structure of a wavefront aberration measuring device, according to a second embodiment of the present invention; 
           [0034]      FIGS. 6A to 6E  are plane views for showing a manner of photographing by the 2-dimensional sensor on the pupil of the objective lens, in the second embodiment; 
           [0035]      FIG. 7  is a plane cross-sectional view of the Shack-Hartmann sensor, for explaining a position shift of a light focusing spot on the 2-dimensional sensor when a stage has pitching; 
           [0036]      FIG. 8  is a front cross-sectional view for showing an outlook structure of a wavefront aberration measuring device, according to a third embodiment of the present invention; 
           [0037]      FIG. 9  is a plane view on a pupil surface of the objective lens, for showing an area or region to be photographed by a 1-dimensional sensor on the pupil of the objective lens when the stage has yawing; 
           [0038]      FIG. 10  is a plane view of a 1-axis stage, for showing a condition of measuring the yawing between the 1-axis stage and a laser measuring instrument, by the laser measuring instrument; 
           [0039]      FIG. 11  is a front cross-sectional view for showing an outlook structure of a wavefront aberration measuring device, according to a fourth embodiment of the present invention; 
           [0040]      FIG. 12  is an outlook cross-sectional view on a front surface of an optical system, for showing an outlook structure for measuring a wavefront aberration of the objective lens through the relay lens; and 
           [0041]      FIG. 13  is a plane cross-sectional view of the Shack-Hartmann sensor, for showing a position where lights are condensed on the 2-dimensional sensor by the array lens when a wavefront has a local inclination. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]    In a Shack-Hartmann type measuring apparatus for measuring a wavefront aberration on the objective lens of an infinite system with using a point-like light source, scanning is made while inclining the Shack-Hartmann sensor to be in parallel with the wavefront, at a pupil position of the objective lens, depending on a position of the point-like light source. Pitching and yawing when the scanning is made are corrected, so as to obtain a spot position of condensed light, and with this, a wavefront aberration coefficient is calculated. 
         [0043]    Explanation will be made on embodiments of the present invention, by referring to the drawings attached herewith. 
       Embodiment 1 
       [0044]    A first embodiment of the present invention will be explained upon basis of  FIGS. 1 to 4 .  FIG. 1  is an entire structure view of the present embodiment. A reference numeral  11  depicts a light source for emitting a parallel light therefrom,  12  a beam expander,  10  a light condenser lens, and  13  a reflection mirror for bending an optical path of light passing through the beam expander  12 . A reference numeral  14  depicts a stage, on which the light source  11 , the beam expander  12 , the reflection mirror  13  and the light condenser lens  10  are mounted, and it has the structure of being movable at least in 1-axis direction. 
         [0045]    A reference numeral  2  depicts an objective lens,  22  a rotation stage, holding the objective lens  2  therein and being rotatable, and  221  an attaching member for fixing the objective lens  2  on the rotation stage  22 , respectively. The rotation stage  22  is retractable to a position completely coming off from an optical axis of the movable light condenser lens  10  in the direction perpendicular to the drawing surface, by means of a driving mechanism, which is not shown in the figure, under a condition of holding the objective lens  2  thereon. A reference numeral  4  depicts the Shack-Hartmann sensor,  41  an array lens being constructed with a large number of minute lenses  4101 ,  4102 ,  4103  and  4104 , which are aligned like an array within a plane (in  FIG. 1  is shown an example of aligning four (4) pieces of the minute lenses, but they may be aligned by a much larger number thereof),  42  a 2-dimensional sensor,  43  a stage being movable at least in a 1-axis direction,  44  a gonio-stage, and  431  a supporting member fixed on the stage  43  for supporting the Shack-Hartmann sensor thereon, respectively. 
         [0046]    The gonio-stage  44  is supported by a Z stage not shown in the figure, to be movable in up and down directions on the drawing surface. A reference numeral  51  depicts a controller system for controlling the stage  14 , the rotation stage  22 , the gonio-stage  44  and the stage  43 . A reference numeral  52  depicts a processor system for processing an output signal from the 2-dimensional sensor  42  of the Shack-Hartmann sensor  4  with using a control signal of the controller system. 
         [0047]    With such structure as was mentioned above, the parallel light emitting from the light source  11 , which is mounted on the stage  14 , after being enlarged by the beam expander  12 , are condensed at a measuring point “A” by the light condenser lens  10 . The light emitting from the point “A” enter onto the objective lens  2 , being a lens to be measured, come to the parallel light being inclined depending on the position of that point “A”, and enter on the Shack-Hartmann sensor  4 , which is provided on the pupil  21  of the objective lens. 
         [0048]    An inclination angle α of the Shack-Hartmann sensor  4  can be obtained from the focus distance “f 1 ” of the objective lens  2  and the distance “L” between the optical axis and the point “A”, with using the Eq. 1 mentioned above. The controller system  51  calculates the inclination angle α by the obtaining the position of the stage, and controls the gonio-stage  44  to be inclined by the inclination angle α. Apart of the parallel light  410  is divided by the array lens  41 , and is photographed as a spot of condensed light on the 2-dimensional sensor  42 , depending on the inclination of the wavefront of each part. Next, the controller system  51  drives the stage  43  so that the Shack-Hartmann sensor  4  moves to a next photographing position of a surface defining the inclination angle α between the pupil  21 , and other part of the parallel light  410  is photographed. While repeating this operation, photographing is conducted on an entire of the pupil  21 . 
         [0049]    Next, explanation will be made in relation with a method for photographing, by referring to  FIGS. 2A to 2E .  FIG. 2A  shows an area or region  4210  photographed by the 2-dimensional sensor  42 , on the region of the pupil  21 , when the stage  43  is at a first position. In the similar manner,  FIGS. 2B ,  2 C and  2 D show the photographing areas or regions  4220 ,  4230  and  4240 , respectively, when the stage  43  is at a second, a third or a fourth position. Each of the photographing area or region  4210 ,  4220 ,  4230  and  4240  is so determined that it overlaps with in a part thereof, respectively. 
         [0050]    A lattice  4212 , in particular, each intersecting point thereof shows a position of the spot position of condensed light from a viewpoint of design (i.e., under an ideal condition thereof), of each of the minute lenses, which build up the array lens  41 . An actual spot  4211  of condensed light is shifted from this position, due to an aberration. The processor system  52 , after obtaining a position of the center of gravity for the spot of condensed light on each picture or image, executes rotation movement and parallel movement onto each arrangement of the spots, so that coordinates of the arrangements  4213 ,  4214 ,  4224  and  4233  of overlapping spots on each picture or image are coincide with, and joins them; finally, obtaining a spot arrangement  450  composed, after being corrected on the position shifts thereof, as is shown in  FIG. 2E . In this manner, by fitting them through the rotation movement and the parallel movement, the yawing and the pitching, being generated when moving by the stage  43 , are corrected. 
         [0051]    Herein, explanation will be given, in relation with the function of the rotation stage  22 , on which the objective lens  2  is mounted. Since the wavefront aberration of the objective lens  2  changes depending on the measuring point “A” (i.e., the focus point “A” of the light condenser lens  10 ), being a relative position with respect to an optical axis  200  of the objective lens  2 , there it must be measured all over the regions within the field of view of the objective lens  2 . On the contrary to this, the gonio-stage  44  is an inclining stage having 1-axis, and the inclination angle thereof is controlled, with respect to the position of the measuring point “A” in a specific radial direction of the objective lens  2 . For executing setup or determination of the measuring points other than this, the objective lens  2  is rotated by the rotation stage  22 . For example, the controlling system  51  rotates the rotation stage  22 , by every 22.5 degrees, and thereby enabling the measurement on almost of all fields of view of the objective lens  2 . 
         [0052]    Thus, in the case shown in  FIG. 3 , the measurement is made on the wavefront aberrations at plural numbers of the measuring points  20011 ,  20012 ,  20013  . . .  2001   n  in the direction along with an axis  2001 , while inclining the gonio-stage  44  into the 1-axis direction, under the condition of fixing the rotation stage  22  at a certain position, and next, the measurement is made on the wavefront aberrations at plural numbers of the measuring points  20021 ,  20022 ,  20023  . . .  2002   n  in the direction along with an axis  2002 , while inclining the gonio-stage  44  into the 1-axis direction, similar manner, under the condition of fixing the rotation stage  22  after rotating it by 22.5 degrees. By repeating this, while rotating the rotation stage at a pitch of 22.5 degrees, it is possible to measure the wavefronts, upon almost all the entire areas or regions within the field of view  201  of the objective lens  2 . 
         [0053]    Next, by referring to  FIG. 4 , explanation will be given on the correction method for correcting the position shift of the spot of condensed light, which is caused due to the aberration of the array lens  41 . First of all, under the condition of retracting the rotation stage  22  from the optical axis of the light condenser lens  10 , by the mechanism not shown in the figure, the controller system  51  drives a Z stage  46  being movable into the up and down directions on the drawing, and thereby moving it to such a position that a spherical wave  100  diverging from the measuring point “A” can enter on the entire of the array lens  41 . 
         [0054]    Now, assuming that the arrangement of the array lens  41  surrounding a center (0,0) of the array lens  41  is (i,j), the distance from the measuring point “A” to the array lens  41  is “R”, and the pitches of the array lens are ΔPx and ΔPy in the X and Y directions thereof, then ideal values ΔX0(i,j) and ΔY0(i,j) on the lattice can be given by the following equations, at the spot of condensed light of the (i,j) th  array lens: 
         [0000]      Δ X 0( i,j )=Δ Px*i*f 4 /R   (Eq. 6)
 
         [0000]      Δ Y 0( i,j )=Δ Py*i*f 4 /R   (Eq. 7)
 
         [0055]    Where, “f 4 ” is the focus distance of the array lens  41 . 
         [0056]    If assuming that the position shift of the spot of condensed light, which is actually measured by the 2-dimensional sensor  42  be ΔXs(i,j), ΔYs(i,j), then the position shift, ΔXa(i,j), ΔYa(i,j), which is caused due to the aberration of the array lens  41 , can be obtained by the following equations: 
         [0000]      Δ Xa ( i,j )=Δ Xs ( i,j )−Δ X 0( i,j )  (Eq. 8)
 
         [0000]      Δ Ya ( i,j )=Δ Ys ( i,j )−Δ Y 0( i,j )  (Eq. 9)
 
         [0057]    The processor system  52 , memorizing the values, ΔXa(i,j), ΔYa(i,j), in advance, corrects the position shift of the spot of condensed light mentioned above, when measuring the objective lens, in accordance with the following equations: 
         [0000]      Δ Xm ( i,j )=Δ X ( i,j )−Δ Xa ( i,j )  (Eq. 10)
 
         [0000]      Δ Ym ( i,j )=Δ Y ( i,j )−Δ Ya ( i,j )  (Eq. 11)
 
         [0058]    With such the process as was mentioned above, it is possible to measure the wavefront aberration of the objective lens  2 , without receiving an ill influence of the aberration of the array lens  41 . 
       Embodiment 2 
       [0059]    A second embodiment of the present invention will be explained by referring to  FIGS. 5  though  7 .  FIG. 5  shows the structure of the wavefront aberration measuring device, enabling to correct an error generated by the yawing and/or the pitching of the stage  23 . The basic or fundamental structure thereof is similar to that of the first embodiment shown in  FIG. 1 , wherein the same reference numerals are attached to the same parts thereof. In the present embodiment, an auto-collimator  45  is attached on the stage  43  mounted on the gonio-stage  44 , differing from the first embodiment shown in  FIG. 1 , in this respect. The auto-collimator  45  measures the yawing angle ω and/or the pitching angle γ of the stage  43 , and thereby sending them to the processor system  52 . 
         [0060]    In  FIGS. 6A to 6E  are shown the manner of photographing, in case when the yawing angle ω and/or the pitching angle γ are/is generated. The conditions shown in  FIGS. 6A to 6D  are basically same to those shown in  FIGS. 2A to 2D , and in  FIG. 6A  is shown the area or region  4210  photographed by the 2-dimensional sensor  42 , on the region of the pupil  21  of the objective lens  2 , when the stage  43  is at the first position thereof. Similarly,  FIGS. 6B ,  6 C and  6 D show the photographing regions  6220 ,  6230  and  6240  when the stage  43  is at the second, third and fourth positions, respectively. A lattice  6212 , in particular, each intersecting point thereof shows a position of the spot position of condensed light from a viewpoint of design (i.e., under an ideal condition thereof), of each of the minute lenses ( 4101 ,  4102 ,  4103  and  4104  shown in  FIG. 1 ), which build up the array lens  41 . The actual spot  6211  (position shown by  in  FIGS. 6A through 6D ) of condensed light is shifted from this position, due to an aberration. 
         [0061]    The processor system  52  receiving the signal from the auto-collimator  45  executes conversion of the coordinates by the following equation, with using the yawing error ω measured, and corrects the arrangement of the spot  6252  by modifying the shift of the photographing region  6250 , as is shown in  FIG. 6B . 
         [0000]    
       
         
           
             
               
                 
                   
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         [0062]    Next, explanation will be given on a relationship between the pitching error γ of the stage  43  and an error ε on the 2-dimensional sensor  42 , by referring to  FIG. 7 . In this case, there is no necessity of photographing while overlapping the spot arrangement between the pictures, as was explained in the embodiment 1. When the 2-dimensional sensor  42  is inclined by γ through the pitching of the stage  43 , a shift volume  8  on the 2-dimensional sensor  42 , which is supported by the supporting member  431  fixed on the stage  43 , can be obtained from the following equation: 
         [0000]      ε= f 4*tan γ  (Eq. 13)
 
         [0063]    Herein, “f 4 ” is the focus distance of the array lens  41 . The processor system  52  calculates the shift volume  8  from the pitching angle γ, which is measured by the auto-collimator  45 , and corrects the spot arrangement  4260 , as is shown in  FIG. 6D . 
         [0064]    In this manner, with measuring the error of movement of the stage  43  by the auto-collimator  45 , it is possible to correct the error of the spot arrangement on the pictures, obtained by photographing at each position of the stage  43 , and by composing each picture characterizing this error, it is possible to obtain the spot arrangement  650 , being corrected on the position shift, as is shown in  FIG. 6E  and composed with. 
       Embodiment 3 
       [0065]    A third embodiment of the present invention will be explained by referring to  FIGS. 8 and 9 .  FIG. 8  shows the structure of other apparatus for obtaining the picture or image of the pupil  21 . The contractual elements same to those of the first embodiment are attached with the same reference numerals. An aspect of the third embodiment differing from those of the first and second embodiments lies in that covering is made over an entire surface of the pupil  21  of the objective lens  2  while fixing a lens array  411 . Thus, the lens array  411  is constructed with a large number of minute lenses  4111 ,  4112 ,  4113  . . . , being aligned or arranged in a lattice manner within the region covering the entire surface of the pupil  21  of the objective lens  2 , and photographing is made on the spots of condensed light, respectively, by the minute lenses  4111 ,  4112 ,  4113  . . . of the lens array  411  through scanning the 1-dimensional sensor  421  in one direction while fixing this array lens  411  on the gonio-stage  44  through a fixing member  432 . 
         [0066]    The 1-dimensional sensor  421  has an image pickup area or region, being equal to or larger than the diameter of the pupil  21 , in the direction perpendicular to the paper surface on  FIG. 8 , and is mounted on a 1-axis stage  430 . A moving distance of the 1-axis stage  430  is measured by means of a laser measuring apparatus  451 . Driving of the 1-axis stage  430  is executed by the controller system  51 , and the processor system  52  composes a 2-dimensional picture from the 1-dimensional image, which is photographed by the lens array  411 , upon basis of a position signal of the laser measuring apparatus  451 . With this, it is possible to pick up an image of a large pupil, which cannot be photographed, directly, by a 2-dimensional CCD, through one (1) time of scanning in one (1) direction. Herein, in  FIG. 9  is shown a locus of photographing area or region  4215  of the 1-dimensional sensor  421 . When a yawing error or shift is generated on the 1-axis stage  430 , a rotation error  4217  is generated in the image pickup region thereof. 
         [0067]    In  FIG. 10  is shown a plane view of the 1-axis stage  430 . Since making measurement with using two (2) axis beams, the laser measuring apparatus  451  is able to measure the yawing angle δ of the 1-axis stage  430 . The processor system  52  corrects or compensates the rotation error  4217  in the photographing region upon the yawing angle δ of the 1-axis stage  430  measured, when composing the picture. With this, the 1-axis stage  430  is able to measure the wavefront aberration, correctly, even if not having high accuracy. Further, in case of applying the 1-dimensional sensor  421  therein, since an influence of the pitching of the 1-axis stage  430  stays within one (1) pixel in the scanning direction, it brings about almost no ill influence upon the accuracy for measuring the wavefront aberration. 
       Embodiment 4 
       [0068]    A fourth embodiment of the present invention will be explained by referring to  FIG. 11 . This  FIG. 11  shows the structure of a wavefront aberration measuring device, for always correcting or compensating an inclination of wavefront, which is generated when a measuring point “A” lies out of an axis, in a predetermined direction. The constituent elements same to those of the first embodiment are attached with the same reference numerals thereof. 
         [0069]    In case where an enough space lies between the surface of the pupil  21  and the objective lens  2 , it is possible to dispose a galvano-mirror  60  at the position of a pupil surface  211 . A controller system  511  calculates a distance “L” of the measuring point “A” up to the optical axis, from a position signal of the stage  14  (e.g., a signal obtained by detecting the position of the stage  14  by a position sensor, such as, the laser measuring apparatus not shown in the figure, etc.), and obtains the inclination angle α (see  FIG. 1 ) of the wavefront on the pupil surface with applying the (Eq. 1); thereby, controlling an angle φ of the galvano-mirror  60  in such a manner that a reflection light  601  always faces to the direction of the optical axis  600 . In more details, the reflection light  601  can be controlled to face to the direction of the optical axis  600 , through inclining the galvano-mirror  60  only by α/2 with respect to the inclination angle α. The reflection light  601  enters on the Shack-Hartmann sensor  4 , in the form of parallel light, through a fixed mirror  61 , a relay lens  3011 , a fixed mirror  62  and a relay lens  3021 . 
         [0070]    In this structure, the Shack-Hartmann sensor  4  is supported by a supporting member, which is not shown in the figure. The relay lenses  3011  and  3021  have the same structures of the relay lenses  301  and  302  shown in  FIG. 12 , wherein the distance on the optical axis between the relay lens  3011  and the pupil surface  211  is determined by the focus distance f 2  (see  FIG. 12 ), the distance between the relay lens  3021  and the array lens  41  by the focus distance f 3  of the relay lens  3021 , and the distance on the optical axis of the relay lenses  3011  and  3021  by f 2 +f 3 , respectively. With this, the array lens  41  has a conjugate relationship between the pupil surface  211 , and upon the array lens  41  enters the wavefront having an entire inclination angle of zero (0) and a phase distribution equal to that on the pupil surface  211 . The magnification obtained by the relay lens  3011  and the relay lens  3021  is so determined, that it satisfies the (Eq. 2). 
         [0071]    According to the present embodiment, there is no necessity of moving the Shack-Hartmann sensor  4 , depending on the position of the measuring point “A”, i.e., it may be always disposed at a fixed position. Since only control of the galvano-mirror  60  is necessary, it is possible to make the measurement of the wavefront aberration out of the axis, with the structure, being simple or easy comparing to that of the embodiments 1 through 3. 
       APPLICABILITY ON THE INDUSTRIES 
       [0072]    As was explained in the above, according to the present invention, it is possible to carry out a lens management for achieving optical inspection apparatuses, having no difference in sensitivity thereof between those machines, in the semiconductor wafer manufacturing line. Also, in the laser machining apparatus for use of the printed-circuit board, it is possible to execute the lens management for ensuring a uniformity of machining configuration all over the scanning region. Further, the present invention is also applicable in an inspection of defect(s) on a hard disk, or on a substrate for use of, such as, a liquid crystal or plasma television, or an organic EL, etc., or a laser machining, a laser correction, etc., for maintain or ensuring the sensitivity and/or the uniformity of the machining configuration, and with this, it is possible to achieve production of those devices at high yield rate. 
       EXPLANATION OF MARKS 
       [0073]      10  . . . condensing lens,  11  . . . light source,  12  . . . beam expander,  13  . . . reflection mirror,  14  . . . stage,  15  . . . 2-dimensional sensor,  2  . . . objective lens,  21  . . . pupil,  211  . . . pupil surface,  22  . . . rotation stage,  200  . . . optical axis,  301  . . . relay lens,  302  . . . relay lens,  4  . . . Shack-Hartmann sensor,  41  . . . array lens,  42  . . . 2-dimensional sensor,  421  . . . 1-dimensional sensor,  430  . . . 1-axis stage,  451  . . . laser measuring apparatus,  43  . . . stage,  44  . . . gonio-stage,  45  . . . auto-collimator,  46  . . . Z-stage,  51  . . . controller system,  52  . . . processor system,  60  . . . galvano-mirror,  61  . . . reflection mirror, and  62  . . . reflection mirror.