JP2008196916A - Optical element evaluation method, optical surface evaluation method, and optical surface evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element evaluation method capable of simply measuring (evaluating) the degree of difference of measuring wave surface data of a test lens from a design value without manufacturing a reference lens. <P>SOLUTION: In this optical element evaluation method, a parallel light flux is allowed to enter the reference lens 14a by simulation, and the first numerical value group determined by totalizing a total distance value from a point image group encircling a point image to a center point image and a total distance value between each adjacent point image group, relative to each point image in the point image group by the emission light flux, is compared with the second numerical value group determined by totalizing the total distance value from the point image group encircling the point image to the center point image and the total distance value between each adjacent point image group, by using a porous plate 5A for allowing a parallel light flux which is the same as the parallel light flux to enter the test lens 8 and a CCD camera 9 for imaging the light flux to acquire it as a point image group, and the result is visualized and expressed, to thereby evaluate the test lens 8. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical element or an optical surface evaluation method, and further to an optical surface evaluation apparatus.

  Conventionally, spherical lenses or aspherical lenses are frequently used as camera lenses. Even if the processing accuracy of the lens is improved, it is difficult to manufacture the projection optical system as designed completely, and various aberrations due to various factors remain in the actually manufactured projection optical system. For this reason, the optical characteristics of the actually produced projection optical system will be different from the designed optical characteristics. In order to inspect the error, a mechanical measurement method using a scan head and an inspection using an interferometer are known. However, such a method requires a long time for the inspection and also adjusts the position of the optical element to be detected. Have difficulty. Also, the inspection device itself is expensive.

  Therefore, various techniques for measuring optical characteristics such as aberration of the actually produced projection optical system have been proposed. For example, in the Hartmann wavefront aberration measurement technique, a spherical wave generated using a pinhole is incident on a test optical system, and the light passing through the test optical system is converted into parallel light, and then the wavefront is divided. The wavefront aberration of the test optical is measured based on the spot image formation position for each divided wavefront.

  A wavefront aberration measuring apparatus (wavefront measuring apparatus) that employs the Hartmann method is, for example, a wavefront dividing element that divides incident light into wavefronts and forms a spot image for each divided wavefront. A microlens array in which a number of minute condensing elements are arranged along a dimensional plane is adopted. Then, a large number of spot images formed by the microlens array are picked up by an image pickup device such as a CCD, the center of gravity of the picked-up waveform of each spot image is obtained, and the spot image position is detected. The position of each spot light image detected in this way represents the local inclination of the wavefront of the light incident on each microlens. Therefore, the wavefront aberration is obtained by reconstructing the wavefront shape of the optical system to be measured two-dimensionally by an operation such as integrating the local inclination of the wavefront.

  According to the wavefront aberration measuring apparatus to which the above-described microlens array is applied, a large number of spot images forming each divided wavefront can be picked up at once, so that prompt wavefront aberration can be measured.

  In the conventional wavefront aberration measuring apparatus, when inspecting how much the measured wavefront aberration varies from the design value, measurement data using a reference lens is required. However, it is very difficult to manufacture a reference lens as designed, which requires a long manufacturing time and is expensive.

  The present invention has been made to solve the above-described problem, and it is easier to determine how much the measured wavefront data of a lens as a subject differs from a design value without manufacturing a reference lens. An object is to provide an optical element evaluation method, an optical surface evaluation method, or an optical surface evaluation apparatus that can be measured (evaluated).

  According to an optical element evaluation method of the present invention, a plurality of parallel light beams parallel to the optical axis are made incident on a designed ideal optical element by simulation, and a plurality of parallel light beams are emitted from the ideal optical element by simulation. Generating a point image group, and in each of the predetermined point images of the point image group, a total numerical value of all distances from the predetermined number of point images surrounding the predetermined point image to the central point image, or A first numerical value group obtained by calculating an ideal total count value obtained by adding the total numerical value and the total numerical value of all the distances between adjacent neighboring point images; Each of the predetermined point images of the point image group using parallel light beam incident means for making the parallel light beam incident thereon and imaging means for capturing the light beam emitted from the manufactured optical element and capturing it as a point image group The predetermined point image The total value of all the distances from a predetermined number of point images enclosing as a heart to the central point image, or the sum of the total value and the total value of all the distances between adjacent neighboring point images The first numerical value group and the second numerical value group are compared and calculated for each predetermined point image position based on the second numerical value group obtained by calculating the total count value, and the comparison result is visualized. Express.

  The optical element evaluation method according to a second aspect of the present invention is the optical element evaluation method according to the first aspect, wherein the first numerical value group and the second numerical value group are the predetermined points for each point image group. Calculation is performed based on a point image group surrounding the image in a lattice pattern.

  The optical element evaluation method according to a third aspect of the present invention is the optical element evaluation method according to the first aspect, wherein the first numerical group and the second numerical group are the predetermined point image for each point image group. Is calculated on the basis of a point image group surrounding the polygonal shape.

  According to an optical element evaluation method of a fourth aspect of the present invention, a plurality of parallel light beams parallel to the optical axis are made incident on a predetermined region centered on the optical axis of the designed ideal optical element by simulation. A plurality of predetermined point image groups are generated by the light beam emitted from the ideal optical element, and the center point is determined from a predetermined number of point images surrounding the predetermined point image in each of the predetermined point images of the point image group. A total number of all distances to the image, or a first group of numerical values obtained by calculating an ideal total count value obtained by summing the total number and the total number of all distances between adjacent neighboring point images; Imaging parallel light beam incident means for causing a plurality of parallel light beams that are the same as the parallel light beam to enter the predetermined area centered on the optical axis of the manufactured optical element; and imaging the light beam emitted from the manufactured optical element. Imaging means for capturing as a point image group In each of the predetermined point images of the point image group, the total numerical value of all the distances from the predetermined number of point images surrounding the predetermined point image to the central point image, or the total numerical value And a second numerical value group obtained by calculating an actual total count value obtained by adding up the total numerical values of all the distances between neighboring point images around the first numerical value for each predetermined point image position based on The group is compared with the second numerical value group, and the manufactured optical element is evaluated based on the difference between the maximum value and the minimum value in the comparison result.

  In the optical element evaluation method according to claim 5 of the present invention, a plurality of parallel light beams parallel to the optical axis are made incident on a predetermined region centered on the optical axis of the ideal optical element in design by simulation. , A plurality of predetermined point image groups are generated by the light flux emitted from the ideal optical element, and the center point image is generated from a predetermined number of point images surrounding each point image in each point image of the point image group. A first numerical value group in which an ideal total count value obtained by summing up the total numerical value of all the distances up to, or the total numerical value and the total numerical value of all the distances between adjacent neighboring point images, Imaging the luminous flux emitted from the manufactured optical element, and a parallel luminous flux incident means for making the same parallel luminous flux as the parallel luminous flux enter the predetermined area centered on the optical axis of the optical element, Imaging means for capturing as a point image group; In each of the predetermined point images of the point image group, the total numerical value of all the distances from the predetermined number of point images surrounding the predetermined point image to the central point image, or the total numerical value and the Based on a second numerical group obtained by calculating an actual total count value obtained by summing up the total numerical values of all distances between adjacent neighboring point images, the first numerical group and the first numerical group for each predetermined point image position based on The two optical value groups are compared, and the manufactured optical element is evaluated with the average value of the numerical value groups of the comparison results.

  An optical element evaluation method according to a sixth aspect of the present invention is the optical element evaluation method according to the fifth aspect, wherein the manufactured optical element is evaluated with an average value of absolute values of a numerical group of the comparison result.

  An optical surface evaluation apparatus according to a seventh aspect of the present invention includes a parallel light beam generating unit that generates a plurality of parallel light beams, an incident unit that causes the plurality of parallel light beams to enter an optical element that is a subject, and the optical element. Imaging means that captures a plurality of emitted light flux images emitted from the optical element, an emitted light flux image of the plurality of parallel light fluxes emitted from the optical element, and a plurality of simulation light images that are the same as the plurality of parallel light fluxes on the ideal optical element in the simulation. Comparing a plurality of simulated exit light flux images on the simulation in which a parallel light flux is incident and exited from the ideal optical element, and between each of the plurality of simulated exit light flux images and the corresponding exit light flux images. And a calculation means for calculating and generating a curved surface representing a deviation from the optical surface of the ideal optical element by a Zernike polynomial using a plurality of relative distances as data.

  An optical surface evaluation apparatus according to an eighth aspect of the present invention is the optical surface evaluation apparatus according to the seventh aspect, wherein the parallel light beam generating means converts a light source and a light beam from the light source into parallel light. And a multi-hole plate that generates a plurality of parallel light beams from a plurality of parallel light beams, and at least one of the holes of the multi-hole plate is in another hole. The hole shape is different.

  According to a ninth aspect of the present invention, there is provided an optical surface evaluation method in which a plurality of parallel light beams are generated from a parallel light beam generating unit that generates a plurality of parallel light beams, and the light beams are incident on an optical element that is a subject. In the simulation of the emitted light image of the plurality of parallel light beams emitted from the element and the plurality of parallel light beams in the same simulation as the plurality of parallel light beams incident on the ideal optical element in the simulation and emitted from the ideal optical element And calculating and generating a curved surface by Zernike polynomials using a plurality of relative distances between each of the simulated emitted light beam images and the corresponding emitted light beam images as data. To evaluate the optical surface of the optical element.

  According to the present invention, an optical element evaluation method, an optical device, and an optical element evaluation method that can more easily measure (evaluate) how much the measurement wavefront data of a lens to be measured differs from a design value without requiring the production of a reference lens. A surface evaluation method or an optical surface evaluation apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block configuration diagram of a lens surface measurement evaluation apparatus which is an optical surface evaluation apparatus as an embodiment of the present invention. FIG. 2 is an enlarged view of a multi-hole plate applied to the lens surface measurement and evaluation apparatus.

  A lens surface measurement and evaluation apparatus 10 according to the present embodiment includes a light source unit 1, a pinhole plate 2 disposed in front of the light source unit 1 along an optical axis O, a filter 3, and a collimator lens that is a parallel light flux generating unit. (Telecentric lens optical system) 4, multi-hole plate 5 </ b> A, diaphragm plate 6, and lens holder 7 to which a test lens 8 that is an optical element (subject) manufactured and fixed is attached. And an ideal optical device corresponding to the lens 8 to be inspected and the CCD camera 9 which is an image pickup means disposed on the optical axis O, an image processing unit 11 which takes a captured image output signal of the CCD camera 9 and performs image processing. A simulation processing unit 14 for simulating a reference lens 14a, which is an element, an image processing unit 11 and an arithmetic processing unit 12 for capturing output data of the simulation processing and performing lens measurement processing; Processing result of the lens accuracy measurement, and a display unit 13. for displaying the evaluation, and the like.

  The light source unit 1 is, for example, a white light source of a halogen bulb or an LED.

  The filter 3 is a monochromatic filter such as red or green for transmitting light of a predetermined wavelength of the light source light. The wavelength is adjusted to the wavelength of the light source light applied to the simulation calculation of the reference lens 14a. The filter 3 may be disposed anywhere between the light source unit 1 and the CCD camera 9. In addition, if the light source is monochromatic light such as an LED, the filter is not necessary.

  The collimator lens 4 converts the light from the light source unit 1 into parallel light and emits it to the multi-hole plate side.

  The multi-hole plate 5A is an inspection multi-hole plate in which small-diameter hole groups penetrating the plate are arranged in a predetermined range in order to generate a plurality of parallel light beams from the light source light. As shown in FIG. 2, the multi-hole plate 5A has small-diameter circular hole groups Sn arranged in a lattice shape in a range wider than the effective diameter D0 of the lens 8 to be examined. Each of the small hole groups Sn has a diameter of 0.08 mm, for example. However, the reference small hole S0 located on the optical axis O has a larger diameter so that it can be distinguished from other small hole groups Sn. Further, the pitch of the lattice is, for example, 0.19 mm.

  Further, the reference small hole S0 is arranged on the optical axis O, but without arranging in this way, a plurality of holes having a diameter larger than other holes are arranged around the optical axis, and the center positions of these hole groups are set. You may make it match | combine with an optical axis. Further, the hole may have an arbitrary shape in addition to the round hole shape.

  It is also possible to apply a multi-hole plate 5B shown in FIG. 3 instead of the multi-hole plate 5A. The multi-hole plate 5B has a small-diameter group of small holes Sn arranged in a lattice shape within the effective diameter D0 of the lens 8 to be examined. Other specifications are the same as those of the multi-hole plate 5A. By using this multi-hole plate 5B, the diaphragm plate 6 becomes unnecessary.

  Furthermore, it is also possible to apply the multi-hole plate 5C shown in FIG. 4 instead of the multi-hole plate 5A. The multi-hole plate 5C is provided with small-diameter circular small hole groups Sn arranged in a twill shape (staggered shape) on the intersections of the line groups K1 to K4 having a predetermined pitch that intersect at a right and left intersection angle of 60 °. Yes. In this case as well, the reference small hole S0 located on the optical axis O has a larger diameter so that it can be distinguished from the other small hole group Sn.

  The aperture plate 6 is an aperture having an opening having an effective lens diameter D0 and is held in close contact with the lower surface of the lens receiving base 7. However, when a plate such as the multi-hole plate 5B is applied as described above, the diaphragm plate 6 is not necessary.

  The lens cradle 7 has a receiving part into which the test lens 8 is fitted without play.

  The lens 8 to be inspected is a manufactured optical element to be inspected, and is a spherical surface, an aspherical lens, or a plurality of surfaces on which the incident surface side made of a glass lens and a plastic lens is flat (may be a curved surface). This is a cemented lens combining these lenses. Further, the lens 8 is supported on the lens base 7 so as to be rotatable about the optical axis O by 180 ° in order to eliminate the influence of the positional deviation of the optical axis O.

  The CCD camera 9 includes a CCD having an imaging surface 9a, an imaging signal processing unit, and the like. On the imaging surface 9a, a plurality of parallel light beams that have passed through the small hole group Sn such as the multi-hole plates 5A, 5B, or 5C and the reference small hole S0 are emitted from the test lens 8 to form a point image group. Note that the position of the imaging surface 9a in the direction of the optical axis O can be adjusted to match the predetermined separation distance H0. However, the front and rear positions of the lens base 7, the multi-hole plate 5A, and the collimator lens 4 may be adjusted. The imaging surface 9a is assumed to have an xy coordinate system that is an orthogonal coordinate centered on the optical axis O. This xy coordinate system is also applied to a reference lens 14a, a test lens 8 and a multi-hole plate which will be described later.

  The image processing unit 11 captures the image signal of the point image group output from the CCD camera 9, performs image processing, and outputs measurement image data including the point image group.

  The arithmetic processing unit 12 includes measurement bright spot position data (described later) obtained based on the measurement image data output from the image processing unit 11, and simulation bright spot position data (described later) output from the simulation processing unit 14. Are compared, and the test lens 8 evaluates the surface accuracy (surface accuracy) and the wavefront accuracy (ass component, coma component) with respect to a reference lens 14a described later. Details of the process will be described later.

  Assuming the case where the reference lens 14a, which is an ideal optical element in optical design corresponding to the lens 8 to be tested, is used, the simulation processing unit 14 generates an assumed light beam parallel to the optical axis O in the multi-hole plates 5A, 5B, Alternatively, a plurality of simulated exit beams corresponding to the small hole group Sn and the reference small hole S0 are assumed by passing through the small hole group Sn and the reference small hole S0 of 5C, exiting from the reference lens 14a, and assuming a plurality of point images on the imaging surface 9a. The position of the assumed point image group, which is an image, is calculated and output as simulation bright spot position data. In the above calculation, the predetermined separation distance H0 described above is adopted as the distance between the imaging surface 9a and the reference lens 14a.

  The measurement processing method for evaluating the surface accuracy and the wavefront accuracy by the lens surface measurement and evaluation apparatus 10 will be described in detail below.

  First, the evaluation of surface accuracy, that is, the degree of unevenness of the optical surface is obtained by obtaining the deviation of each bright spot position of the lens bright spot position data with respect to the simulation bright spot position data, and the surface of the lens 8 to be tested is used as a reference. The state of the lens 14a will be evaluated. Specifically, in the arithmetic processing unit 12, a plurality of point images of the assumed light fluxes that have passed through each of the small hole group Sn and the reference small hole S 0 with respect to the simulation bright spot position data of the reference lens obtained by the simulation processing unit 14. The group is set as a target bright spot group by the reference lens 14a (hereinafter, each of these bright spot groups is referred to as a SIM target bright spot group). Further, a plurality of adjacent point image groups surrounding the point image group are set as the peripheral bright spot group of the reference lens 14a (hereinafter, each bright spot group is referred to as a SIM peripheral bright spot group). Then, the equivalent position data on the imaging surface of the SIM attention bright spot group and the SIM peripheral bright spot group is stored as SIM bright spot position xy coordinate data.

  Furthermore, the bright spot position data of the point image group on the imaging surface 9a is calculated based on the measurement image data of the lens to be tested output from the image processing unit 11. However, the bright spot position of the point image is determined as the bright spot position by obtaining the barycentric position of the point image by the small hole group Sn and the reference small hole S0. Then, the center point of a plurality of point images by the light transmitted through each of the small hole group Sn and the reference small hole S0 is set as a measurement target bright point group of the point image group of the lens 8 to be examined. Further, each measurement target bright spot image is surrounded, and adjacent peripheral point image groups are set as measurement peripheral bright spot groups of the lens 8 to be examined. Then, the position data on the imaging surface of each measurement target bright spot and the measurement peripheral bright spot group of each measurement target bright spot is stored as measurement bright spot position xy coordinate data.

  FIG. 5 shows specific examples of the SIM noticed bright spot by the reference lens 14a when the multi-hole plate 5A or 5B is applied and the SIM peripheral bright spots around the SIM noticeable bright spot. In the drawing, a SIM notice bright spot corresponding to one small hole S1 of the multi-hole plate 5A (FIG. 2) or 5B (FIG. 3) is indicated by P1. The SIM peripheral bright spots corresponding to the small holes S2 to S8 around the small hole S1 are denoted by P2 to P8.

  Moreover, the specific example of the said measurement attention luminescent spot of the to-be-tested lens 8 at the time of applying multi-hole plate 5A or 5B and the measurement periphery luminescent spot around it is shown in FIG. In the figure, P1 'indicates the measurement target bright spot of the point image corresponding to one small hole S1 of the multi-hole plate. The measurement peripheral bright spots of the point images corresponding to the small holes S2 to S8 around the small hole S1 are denoted by P2 'to P8'. As shown in FIG. 6, the measurement peripheral bright spots P2 'to P8' around the measurement target bright spot P1 'are displaced by the accuracy of the surface of the lens 8 to be tested.

  The calculation of the bright spot separation distance and the measurement bright spot separation distance by the simulation (SIM) described above is performed in the case of the multi-hole plate 5A, 5B, or 5C described later, as shown in FIG. The point image group by all the small hole groups S0 and Sn existing within the evaluation target diameter D1 (for example, 6.00 mm) of the designated area smaller than the effective lens diameter D0 (for example, 6.51 mm) is calculated as the target bright spot. Is done. The reason why the designated area is set in this way is that, when calculating the measured bright spot separation distance, a small hole for the peripheral bright spot is also required outside the target bright spot.

  The arithmetic processing unit 12 calculates the mutual separation distance between the SIM target bright spot P1 and the SIM peripheral bright spots P2 to P8 surrounding the bright spot P1 from the SIM bright spot position xy coordinate data of the reference lens. Specifically, the SIM bright spot separation distances La to Ld, which are the distances between the SIM focused bright spot P1 and the SIM peripheral bright spots P2, 4, 6, 8, and the adjacent bright spots of the SIM peripheral bright spots P2 to P9. SIM bright spot separation distances Le to Lm, which are the distances of. Calculations between the bright spot P1 and the bright spots P3, P5, P7, and P9 may be made, but are omitted in this embodiment.

Then, a SIM bright spot separation distance addition value Lsum obtained by summing the SIM bright spot separation distances La to Ld and Le to Lm is calculated. That is,
Lsum = La + Lb +... + Lk + Lm (1)
Is calculated.

  This SIM bright spot separation distance addition value Lsum is calculated for all SIM attention bright spots P, and as the first numerical group that is an ideal total count value, the SIM bright spot separation distance addition value ( Group) Lsum-Z, that is, Lsum-1, 2, 3,.

On the other hand, the mutual separation distance between the measured bright spot P1 'and the measured peripheral bright spots P2' to P8 'surrounding the bright spot P1' is calculated from the measured bright spot position xy coordinate data of the lens to be examined. Specifically, the measurement bright spot separation distances La ′ to Ld ′, which are distances between the measurement target bright spot P1 ′ and the measurement peripheral bright spots P2 ′, 4 ′, 6 ′ and 8 ′, and the measurement peripheral bright spots P2 ′ to Measured bright spot separation distances Le 'to Lm' which are distances between adjacent bright spots of P9 'are calculated. Then, a measured bright spot separation distance addition value Lsum ′ obtained by adding the measured bright spot separation distances La ′ to Ld ′ and Le ′ to Lm ′ is calculated. That is,
Lsum ′ = La ′ + Lb ′ +... + Lk ′ + Lm ′ (2)
Is calculated.

  The measured bright spot separation distance addition value Lsum ′ is calculated for all the measurement bright spots P ′, and is added as a second numerical group that is an actual total count value. The value (group) Lsum-Z ′, that is, Lsum−1 ′, 2 ′, 3 ′... Is stored in the memory.

Subsequently, the measured bright spot separation distance addition value (group) Lsum-Z ′ and the SIM bright spot separation distance addition value (group) of the SIM attention bright spot P corresponding to each measurement notice bright spot P ′ of the test lens 8. ) The difference from Lsum-Z is calculated as a measured bright spot separation distance difference value (group) ΔLsum-Z ′ for each measured bright spot P ′ of the lens 8 to be examined. Specifically, let n be the total number of bright spots P ′ to be measured.
ΔLsum-1 ′ = Lsum-1′−Lsum-1
ΔLsum-2 '= Lsum-2'-Lsum-2
...
ΔLsum-n ′ = Lsum-n′−Lsum-n (3)
Are calculated and stored in the memory respectively.

  Each of the measured bright spot separation distance difference (group) ΔLsum-Z ′ described above is the accuracy of the surface around the target bright spot P ′ of the test lens 8, that is, the surface of the test lens 8 is the reference lens. It is a value indicating the degree of whether it is more convex (when the value is +) or more concave (when the value is-) with respect to the surface 14a.

  Next, calculation processing when the multi-hole plate 5C is applied will be described. FIG. 7 shows a specific example of the distribution of the SIM noticeable luminescent spot and the SIM peripheral luminescent spot by the reference lens 14a when the multi-hole plate 5C is applied. FIG. In the figure, a SIM notice bright spot corresponding to one small hole S11 of the multi-hole plate 5C is indicated by P11. The SIM peripheral bright spots corresponding to the small holes S12 to S17 around the small hole S11 are denoted by P12 to P17.

  Moreover, the specific example of the said measurement attention luminescent spot and measurement peripheral luminescent spot of the to-be-tested lens 8 at the time of applying the multi-hole plate 5C is shown in FIG. In the figure, the measurement target bright spot of the point image corresponding to one small hole S11 of the multi-hole plate is indicated by P11 '. The measurement peripheral bright spots of the point images corresponding to the small holes S12 to S17 around the small hole S11 are denoted by P12 'to P17'. As shown in FIG. 8, the measurement peripheral bright spots P12 'to P17' around the measurement target bright spot P11 'are displaced by the accuracy of the surface of the lens 8 to be examined.

  The arithmetic processing unit 12 calculates SIM bright spot separation distances Ln to Ly, which are mutual separation distances between the SIM bright spot P11 and the SIM peripheral bright spots P12 to P17, from the SIM bright spot position xy coordinate data. Further, from the measured bright spot position xy coordinate data, the measured bright spot separation distances Ln ′ to Ly ′, which are the mutual separation distances of the measurement target bright spot P11 ′ and the respective measurement peripheral bright spots P12 ′ to P17 ′, are calculated.

  The arithmetic processing unit 12 calculates the mutual separation distance between the SIM attention bright spot P11 and the SIM peripheral bright spots P12 to P17 surrounding the bright spot P11 from the SIM bright spot position xy coordinate data. Specifically, the SIM bright spot separation distances Ln to Ls, which are the distances between the SIM notice bright spot P11 and the SIM peripheral bright spots P12 to P17, and the distance between adjacent bright spots of the SIM peripheral bright spots P12 to P17. SIM bright spot separation distances Lt to Ly are calculated. On the other hand, from the measured bright spot position xy coordinate data, the mutual separation distance between the measurement target bright spot P11 'and the measurement peripheral bright spots P12' to P17 'surrounding the bright spot P11' is calculated. Specifically, the measurement bright spot separation distances Ln ′ to Ls ′, which are distances between the measurement target bright spot P11 ′ and the measurement peripheral bright spots P12 ′ to P17 ′, and the measurement peripheral bright spots P12 ′ to P17 ′ are adjacent to each other. The measured bright spot separation distances Lt ′ to Ly ′, which are the distances between the bright spots, are calculated.

  Then, a SIM bright spot separation distance addition value Lsum obtained by summing the SIM bright spot separation distances Ln to Ls and Lt to Ly is calculated, and the measurement bright spot separation distances Ln ′ to Ls ′ and Lt ′ to Ly ′ are summed. The measured bright spot separation distance addition value Lsum ′ is calculated.

  Similarly, when this multi-hole plate 5C is applied, the measured bright spot separation distance addition value (group) Lsum-Z 'and the corresponding SIM bright spot separation distance addition value for each measurement target bright spot P ′ of the lens 8 to be tested. The difference from (group) Lsum-Z is calculated and stored as a measured bright spot separation distance difference value (group) ΔLsum-Z ′ for each measured target bright spot P ′ of the test lens 8.

  In the example in which the multi-hole plates 5A, 5B, and 5C described above are applied, the polygon formed by the peripheral bright spots with respect to the target bright spot has been described as a square or a regular hexagon. However, the present invention is not limited to this. It is possible to specify peripheral bright spots using other multi-hole plates and applying other polygons.

  In the lens surface measurement and evaluation apparatus 10, a method of visually evaluating the surface accuracy (surface distortion) can be used. In this method, in order to visually discriminate the degree of accuracy of the surface of the lens 8 to be examined, for example, the range of the measurement bright spot separation distance difference value (group) ΔLsum-Z ′ at each measurement target bright spot is arbitrarily set. This is a method of recognizing the change in accuracy of the surface around each measurement target luminescent spot in the designated area of the lens 8 to be detected by color display.

  FIG. 9 shows the correspondence relationship between the range of the measured bright spot separation distance difference value (group) ΔLsum-Z ′ and each display color, and instead of the corresponding display color applied in FIG. 10 described later. The correspondence with the display figure used for is also shown. As shown in the figure, each range of measured bright spot separation distance difference (group) ΔLsum-Z ′, for example, 2.5 μm or more, 2.5 to 1.5 μm,..., −1.5 to Each color of purple, indigo,..., Orange, and red corresponds to −2.5 μm and −2.5 μm or less.

  FIG. 10 shows an example of the actual measurement result of the lens to be measured. The distribution of the measured bright spot separation distance difference value (group) ΔLsum-Z ′ for each target bright spot by the test lens is replaced with the corresponding display color and the corresponding pattern. It is the figure shown by.

  Although the pattern display is shown in FIG. 10, the distribution of the measured bright spot separation distance difference value ΔLsum-Z ′ on the surface of the lens 8 to be measured can be recognized depending on the color, and the accuracy of the lens surface can be easily achieved. Can be evaluated. For example, if there are many portions near the display pattern (green) Zd portion in the designated area 8a of the test lens 8, the accuracy of the surface of the test lens 8 is good, and the display pattern (red) Zg or display pattern (purple) If there are many portions close to Za, it can be said that the accuracy of the surface of the lens 8 is poor.

  When the surface accuracy (surface distortion) is numerically evaluated by the lens surface measurement / evaluation apparatus 10, the following three methods are performed based on the measured bright spot separation distance difference (group) ΔLsum-Z ′. Can be selected and evaluated. That is, as the first evaluation method, an evaluation method for evaluating the difference between the maximum value and the minimum value in each measured bright spot separation distance difference value (group) ΔLsum-Z ′ in the designated area, and the second evaluation method An evaluation method for evaluating the absolute value of each absolute value of each measured bright spot separation distance value (group) ΔLsum-Z ′ in the designated area, and a third evaluation method for each measured brightness in the designated area It is possible to select and apply an evaluation method that evaluates the average value of the point separation distance difference value (group) ΔLsum-Z ′ itself (considering + −) for the entire designated area.

  In the first evaluation method, the evaluation is performed based on the difference between the maximum value ΔLsum-max ′ and the minimum value ΔLsum-min ′ of each measured bright spot separation distance difference value (group) ΔLsum-Z ′ in the designated area. .

In the second evaluation method, the evaluation is performed based on an average value ΔLab-sum-avg ′ of absolute values of each measured bright spot separation distance difference value (group) ΔLsum-Z ′ in the designated area. The average value ΔLab-sum-avg ′ of each absolute value is n as the number of bright spots to be measured.
ΔLab-sum-avg ′ = (Σ | ΔLsum-Z ′ |) / n
= (| ΔLsum-1 '| + ... + | ΔLsum-n' |) / n (4)
Given in.

In the third evaluation method, the evaluation is performed based on an average value ΔLsum-avg ′ (without using an absolute value) in consideration of the + −value of each measured bright spot separation distance value (group) ΔLsum-Z ′ in the designated area. Do. The average value ΔLsum-avg ′ is defined as n as the number of measurement bright spots.
ΔLsum-avg ′ = (ΣΔLsum-Z ′) / n
= (ΔLsum-1 ′ +... + ΔLsum-n ′) / n (5)
Given in.

  The accuracy of the surface of the test lens 8 can be quantitatively evaluated by the first to third methods described above.

  To measure the point image position on the imaging surface 9a by the small hole group of the multi-hole plates 5A, 5B, and 5C in order to measure the above-described measurement target bright spot and measurement peripheral bright spot, It is necessary to correct the position of the point image (bright spot) described below.

  First, in order to eliminate an error in attaching the lens 8 to the lens cradle due to the eccentricity of the optical axis O position of the lens 8 to be tested, the point image (bright spot) position is measured at the initial mounting position and then rotated 180 °. Then, the point image (bright spot) position is measured again. A point image (bright spot) position obtained by averaging the xy coordinates of the point image position measured at the first mounting position and the xy coordinates of the measured point image position after 180 ° rotation is used for the calculation of the measured bright spot position xy coordinate data described above. Use. By averaging the point image positions, errors due to the eccentricity of the optical axis O position of the test lens 8 can be eliminated.

  Further, when measuring the position of the point image (bright spot) of the lens 8 to be examined, the position of the CCD camera 9 in the direction of the optical axis O is a predetermined separation distance H0 (distance applied in the simulation) between the aforementioned lens and the imaging surface. To fit. However, it is difficult to completely match the separation distance H0. In a state where the distance between the lens and the imaging surface is not located at the predetermined separation distance H0, a magnification error occurs between the point image position by the simulation by the reference lens 14a and the point image position measured by the lens 8 to be examined. It is necessary to perform magnification error correction. Further, it is necessary to add an error correction due to field curvature according to the separation distance L50 (measured value) from the optical axis O to each point image (bright spot) position. The design value of the separation distance H0 is, for example, 50 mm.

  Therefore, the position of the CCD camera 9 in the direction of the optical axis O is adjusted to a predetermined distance H0 within a certain range of error, and the measurement magnification is corrected from the difference between the distance H0 and the actual distance between the actually measured lens and the imaging surface. A coefficient (big-ratio) Bm is obtained.

Further, using the separation distance L50, a field curvature correction coefficient Wc for eliminating the field curvature error at each point image (bright spot) position is obtained. This field curvature correction coefficient Wc is
Wc = ((1-W50) / (1-Bm0)) * (Bm-1) +1 (6)
Given in.

  The field curvature correction coefficient Wc is a coefficient that becomes 1 when the distance error between the lens and the imaging surface is 0. When the measurement magnification correction coefficient Bm is a predetermined correction coefficient Bm0, the field curvature correction coefficient Wc is assumed to be W50, and the field curvature correction coefficient Wc when another measurement magnification correction coefficient Bm is 6). However, the value of W50 is a field curvature correction coefficient obtained by simulation when the separation distance is -50 .mu.m (that is, the imaging surface is located 50 .mu.m before the separation distance H0). Since the value of Bm0 varies depending on the designed lens specifications, it is stored in the memory of the arithmetic processing unit 12 in advance.

In order to perform magnification correction and field curvature correction of the measured bright spot position data, each point image (brightness) is obtained from the optical axis O using the field curvature correction coefficient Wc and the measurement magnification correction coefficient Bm according to the above equation (6). The separation distance L50 (measured value) to the point) position is corrected. That is, the corrected value L50 of the separation distance L50 is
L50 correction value = L50 / (Bm × Wc) (7)
Is required.

  The corrected measurement bright spot position data (L50 correction value) is obtained by applying the equation (7) and performing magnification correction and field curvature correction of the separation distance L50 (measurement value).

  Next, a modification of the surface accuracy evaluation method by the lens surface measurement evaluation apparatus 10 of the present embodiment will be described. In the surface accuracy evaluation method of this modification, when the calculation of the SIM, the measurement bright spot separation distance and the calculation of the measurement bright spot separation distance is performed, the inside of the evaluation target diameter D1 of the multi-hole plate shown in FIG. The designated area 8a of the test lens 8 corresponding to is divided by four types of division methods (FIGS. 11 to 14). Then, the average value of the measured bright spot separation distances of each target bright spot in each divided area is obtained, and the difference between the maximum value and the minimum value of the average value between the divided areas is obtained as an APV value. The accuracy of the surface of the test lens 8 is evaluated based on the APV value.

  11, 12, 13, and 14 show a state in which the designated area is divided by the first, second, third, and fourth area dividing methods, respectively.

  The first and second area division methods shown in FIGS. 11 and 12 both divide the designated area 8a of the lens 8 to be divided into two on the inner and outer circumferences with a dividing line circle Q0 as a circle of a predetermined diameter. A plurality of straight dividing lines passing through the optical axis O divide the inner peripheral area on the inner side of the dividing line circle Q0 into eight parts at equal angles in the circumferential direction, and similarly, the outer peripheral area on the outer side of the dividing line circle Q0. The area is divided into 16 parts, and the entire area is divided into 24 parts.

  However, in the first area dividing method according to FIG. 11, the inner peripheral area is divided into eight equal parts by a radial dividing line along the x axis and the y axis and an inclined radial dividing line with an inclination angle of 45 °. (Divided areas E1, E2, etc.). Further, the outer peripheral area is further divided by the radial direction dividing line between the radial direction dividing line and the inclined radial direction dividing line along the x-axis and y-axis to be divided into 16 equal parts (divided areas E3, E4). etc).

  On the other hand, in the second division method shown in FIG. 12, the inner circumferential area is divided into eight equal parts in the circumferential direction along the radial dividing line across the x axis and the y axis (divided areas E11, E12, etc.). Furthermore, the outer peripheral side area is divided into 16 equal parts in the circumferential direction by a radial dividing line in a state straddling the x-axis and the y-axis and a dividing line in a state straddling an inclined line having an inclination angle of 45 ° (divided areas E13, E14). etc). The radial dividing lines according to the first dividing method and the radial dividing lines according to the second dividing method do not overlap, but the dividing line circle Q0 is common. In the case of the second area dividing method, the dividing lines do not intersect each other. In addition, the area E0 around the optical axis O is excluded from the inner peripheral area in both the first and second area dividing methods.

  In the third and fourth area dividing methods shown in FIGS. 13 and 14, the designated area 8a of the lens 8 to be examined is cut into a ring shape with predetermined small and large dividing line circles Q1 and Q2, and the ring is further divided. The area is divided into 12 fan-shaped sections along six radial dividing lines passing through the optical axis O (divided areas E21, E22, etc., or divided areas E31, E32, etc.). The area of each of these divided areas is approximately equal to the area of the divided areas obtained by the first and second area dividing methods. In the third area dividing method of FIG. 13, two of the six dividing lines are dividing lines along the x-axis and y-axis passing through the optical axis O. In the fourth dividing method of FIG. 14, four of the six dividing lines are dividing lines that cross the x axis and the y axis that pass through the optical axis O. Further, the circumferential dividing lines Q1, Q2 are at positions that do not overlap with the circumferential dividing line Q0 in the first and second dividing methods.

  According to the first, second, third, and fourth division methods described above, the designated area 8a of the test lens 8 has 72 types of areas. For each divided area divided by each division method, for example, a measured bright spot separation distance difference value (group) ΔLsum-Z ′ obtained for each target bright spot is obtained (Equation (3)). Further, an average value ΔLsum-avg ′ of the measured bright spot separation distance difference (group) ΔLsum-Z ′ is obtained for each divided area (Equation (5)). The difference between the maximum value and the minimum value of the average value ΔLsum-avg ′ in the 72 types of areas is defined as an APV value, and the accuracy of the surface of the lens 8 to be examined is evaluated based on the APV value.

  The average value ΔLsum-avg ′ of the measured bright spot separation distance difference value (group) is an average value of the absolute values of the measured bright spot separation distance difference value (group) ΔLsum-Z ′ as shown in the equation (4). ΔLab-sum-avg ′ can also be applied.

  According to the method for evaluating the accuracy of the surface of the lens 8 to be tested to which the area dividing method described above is applied, the accuracy when the lens is viewed in a plurality of divided area units can be evaluated, and a Zernike polynomial described later is applied. Thus, evaluation different from the method of detecting the AS and COMA components of the lens can be obtained.

  And since the radial dividing lines do not overlap with each other in the first dividing method and the second dividing method as described above, the average lost by passing the radial dividing lines in one dividing method Value data is obtained by the other division method. Furthermore, since the area through which the circumferential dividing line in the first and second dividing methods passes can be measured by the third and fourth dividing methods, the average lost by the circumferential dividing line in the first and second dividing methods. Value data can be obtained by the third and fourth division methods. Further, in the third and fourth dividing methods, the radial dividing lines do not overlap each other, and the average value data lost in the radial dividing line in one dividing method is obtained by the other dividing method. . In this way, since there is no undetectable average value data lost due to the dividing line, it is possible to evaluate the accuracy of the surface without any oversight, in other words, the unevenness of the portion of the optical surface.

  In the above description, the total value of all the distances from a predetermined number of point images surrounding the point image that is the target bright point to the center point image, and all the distances between adjacent neighboring point images. The total count value obtained by summing up the total numerical values was calculated, but this was simplified, and only the total numerical values of all the distances from the predetermined number of point images surrounding the point image that is the target bright point to the central point image were calculated. You may make it evaluate based on.

  Next, a method for evaluating the lens wavefront accuracy including an as (AS) component and a coma (COMA) component using the lens surface measurement and evaluation apparatus 10, in other words, from the ideal optical surface of the entire optical surface. A method for evaluating the deviation of the shape will be described. The above-described as component and coma component are evaluated by applying the simulation result of the reference lens 14a and the actual measurement result of the test lens 8 to a Zernike polynomial.

The cylindrical function w (r, θ) that gives the shape of the wavefront of the lens, which is the Zernike polynomial, is expressed by the following equation. That is,
w (r, θ) = Z 1 + Z 2 × r × cos θ + Z 3 × r × sin θ + Z 4 × (2r ² −1)
+ Z5 × r ² × cos 2θ + Z 6 × r ² × sin 2θ + (8)
It is. However, r and (theta) show the radius and angle which give the luminescent point position by the multi-hole plate 5A on the imaging surface by a polar coordinate, for example. Zn is a coefficient depending on the shape of the lens.

In the cylindrical function, the as component AS of the test lens 8 is given by the coefficients Z5 and Z6 of the equation (8) obtained from the wavefront shape difference of the test lens 8 with respect to the reference lens 14a.
AS = 2 × (Z5 ² + Z6 ² ) ^1/2 (9)
Indicated by

In the cylindrical function, the coma component COMA of the lens 8 to be examined is similarly given by the coefficients Z7 and Z8 in the equation (8).
COMA = 3 × (Z7 ² + Z8 ² ) ^1/2 (10)
Indicated by

On the other hand, the deviation amounts x and y of the bright spot position data between the reference lens 14a and the test lens 8 described above are given by the xy coordinates which are orthogonal coordinate systems on the imaging surface 9a.
x = r × cos θ
y = r × sinθ
Perform coordinate transformation using.

Then, let r0 be 1/2 of the lens effective diameter D0, and apply ρ = r / r0.
r0 × ∂w (ρ, θ) / ∂x = ∂w (ρ, θ) / ∂ρ × cosθ
+ ∂w (ρ, θ) / ∂θ × sinθ / ρ (11)
r0 × ∂w (ρ, θ) / ∂y = ∂w (ρ, θ) / ∂ρ × sinθ
+ ∂w (ρ, θ) / ∂θ × cosθ / ρ (12)
Then, the above equations (11) and (12) are solved by the least square method based on the deviations x and y of the bright spot position data between the reference lens 14a and the test lens 8, and the coefficient Zn to be fitted is obtained.

  AS and COMA are obtained by substituting the obtained coefficients Z5 and Z6 and coefficients Z7 and Z8 into the equation (9) or (10).

  As described above, the as component (AS) and the coma component (COMA) of the lens wavefront accuracy can be obtained from the simulation result of the reference lens 14a by the reference lens 14a and the measurement result of the test lens 8. That is, it is possible to evaluate the optical surface of the lens (optical element) manufactured based on the curved surface obtained by these operations and the value of each term of the Zernike polynomial.

  According to the lens surface measurement and evaluation apparatus 10, a plurality of parallel light beams are incident on the lens, and the distance between the point images of the emitted light beam is obtained by the simulation of the reference lens and the actually measured value of the test lens. By evaluating the difference, it is possible to quickly determine the accuracy of the lens surface without producing a highly accurate and expensive reference lens.

  The optical element evaluation method or the optical surface evaluation method according to the present invention more easily measures (evaluates) how much the measurement wavefront data of the lens to be measured differs from the design value without manufacturing a reference lens. Can be used as a method that can.

It is a block block diagram of the lens surface measurement evaluation apparatus which is an optical surface evaluation apparatus as one Embodiment of this invention. It is an enlarged view of the multi-hole plate applied to the lens surface measurement evaluation apparatus of FIG. It is an enlarged view of the multi-hole board of another shape applied to the lens surface measurement evaluation apparatus of FIG. It is an enlarged view of the multi-hole board of another shape applied to the lens surface measurement evaluation apparatus of FIG. FIG. 4 is a diagram illustrating an example of a distribution of SIM attention luminescent spots and SIM peripheral luminescent spots by a reference lens when the multi-hole plate shown in FIGS. 2 and 3 is applied in the lens surface measurement and evaluation apparatus of FIG. 1. FIG. 4 is a diagram showing an example of distribution of measurement target luminescent spots and measurement peripheral luminescent spots by a test lens when the multi-hole plate shown in FIGS. 2 and 3 is applied in the lens surface measurement and evaluation apparatus of FIG. 1. FIG. 5 is a diagram illustrating an example of a distribution of SIM attention luminescent spots and SIM peripheral luminescent spots by a reference lens when the multi-hole plate shown in FIG. 4 is applied in the lens surface measurement and evaluation apparatus of FIG. 1. FIG. 5 is a diagram illustrating an example of a distribution of a measurement target bright spot and a measurement peripheral bright spot by a test lens when the multi-hole plate shown in FIG. 4 is applied in the lens surface measurement evaluation apparatus of FIG. 1. It is a figure which shows the correspondence of the range of the value of measured bright spot separation distance difference value (DELTA) Lsum-Z 'and each display color in the lens surface measurement evaluation apparatus of FIG. 1 shows an example of the actual measurement result of the lens to be measured by the lens surface measurement and evaluation apparatus in FIG. 1, and shows the distribution of the measured bright spot separation distance difference value ΔLsum-Z ′ for each target bright spot with a corresponding figure instead of the corresponding display color. It is a figure. The state which divided | segmented the designated area of the lens with the 1st area division method applied to the modification of the surface accuracy evaluation method in the lens surface measurement evaluation apparatus of FIG. 1 is shown. The state which divided | segmented the designated area of the lens with the 2nd area division method applied to the modification of the surface accuracy evaluation method in the lens surface measurement evaluation apparatus of FIG. 1 is shown. The state which divided | segmented the designated area of the lens with the 3rd area division method applied to the modification of the surface accuracy evaluation method in the lens surface measurement evaluation apparatus of FIG. 1 is shown. The state which divided | segmented the designated area of the lens by the 4th area division method applied to the modification of the surface accuracy evaluation method in the lens surface measurement evaluation apparatus of FIG. 1 is shown.

Explanation of symbols

4 ... Collimator lens (parallel beam incident means)
8 ... Test lens (manufactured optical element)
9 ... CCD camera (imaging means)
14a: Reference lens (ideal optical element)
Lsum-Z ... SIM bright spot separation added value (group)
(First numerical group)
Lsum-Z '... Measured bright spot separation distance addition value (group)
(Second numerical group)
P1 to P9, P11 to P17
... Bright spot (point image position by ideal optical element)
P1 'to P9', P11 'to P17'
... Bright spot (Position of point image by manufactured optical element)
ΔLsum-max ′: Maximum value ΔLsum-min ′: Minimum value ΔLab-sum-avg ′: Average value of absolute value ΔLsum-avg ′: Average value

Claims (9)

By simulation, a plurality of parallel light beams parallel to the optical axis are made incident on the ideal optical element in the design, and a plurality of point image groups are generated by the light beams emitted from the ideal optical element. In each point image, the total numerical value of all distances from the predetermined number of point images surrounding the predetermined point image to the central point image, or between the total numerical value and the neighboring point images around it A first group of numerical values obtained by calculating an ideal total count value obtained by summing up the total numbers of all distances;
A parallel light beam incident means for causing a plurality of parallel light beams that are the same as the parallel light flux to enter the manufactured optical element; and an imaging means for capturing the light beam emitted from the manufactured optical element and capturing it as a point image group. In each of the predetermined point images of the point image group, the total numerical value of all the distances from the predetermined number of point images surrounding the predetermined point image to the central point image, or the total numerical value and the A second numerical value group obtained by calculating an actual total count value obtained by summing the total numerical values of all the distances between adjacent neighboring point images;
An optical element evaluation method comprising: comparing and calculating the first numerical value group and the second numerical value group for each of the predetermined point image positions based on the above, and visualizing and expressing the comparison result. 2. The first numerical value group and the second numerical value group are calculated based on a point image group surrounding the predetermined point image in a lattice shape for each point image group. Optical element evaluation method. The first numerical value group and the second numerical value group are calculated based on a point image group that surrounds the predetermined point image in a polygonal shape for each point image group. Optical element evaluation method. By simulation, a plurality of parallel light beams parallel to the optical axis are made incident on a predetermined region centered on the optical axis of the designed ideal optical element, and a plurality of predetermined points are obtained by the light beam emitted from the ideal optical element. Generating an image group, and in each of the predetermined point images of the point image group, a total numerical value of all distances from a predetermined number of point images surrounding the predetermined point image to the central point image, or A first numerical value group obtained by calculating an ideal total count value obtained by summing the total numerical value and the total numerical value of all distances between adjacent neighboring point images;
Imaging parallel light beam incident means for causing a plurality of parallel light beams that are the same as the parallel light beam to enter the predetermined area centered on the optical axis of the manufactured optical element; and imaging the light beam emitted from the manufactured optical element. All distances from the predetermined number of point images surrounding the predetermined point image to the central point image in each of the predetermined point images of the point image group. A second numerical group obtained by calculating an actual total count value obtained by summing the total numerical value, or the total numerical value and the total numerical value of all the distances between adjacent neighboring point images,
The first numerical value group and the second numerical value group are compared for each predetermined point image position on the basis of the above, and the manufactured optical element has a difference between the maximum value and the minimum value in the comparison result. An optical element evaluation method characterized by evaluating. By simulation, a plurality of parallel light beams parallel to the optical axis are made incident on a predetermined region centered on the optical axis of the designed ideal optical element, and a plurality of predetermined points are obtained by the light beam emitted from the ideal optical element. Generating an image group, and for each point image of the point image group, a total numerical value of all distances from a predetermined number of point images surrounding the point image to the central point image, or the total numerical value A first numerical value group obtained by calculating an ideal total count value obtained by adding up the total numerical values of all distances between adjacent neighboring point images;
Imaging parallel light beam incident means for causing a plurality of parallel light beams that are the same as the parallel light beam to enter the predetermined area centered on the optical axis of the manufactured optical element; and imaging the light beam emitted from the manufactured optical element. All distances from the predetermined number of point images surrounding the predetermined point image to the central point image in each of the predetermined point images of the point image group. Or a second numerical value group obtained by calculating an actual total count value obtained by summing the total numerical value and the total numerical value of all the distances between adjacent neighboring point images,
The first numerical value group and the second numerical value group are compared and calculated for each predetermined point image position based on the above, and the manufactured optical element is evaluated with an average value of the numerical value groups of the comparison results An optical element evaluation method. The optical element evaluation method according to claim 5, wherein the manufactured optical element is evaluated with an average value of absolute values of a numerical group of the comparison result. A parallel light flux generating means for generating a plurality of parallel light fluxes;
An incident means for making the plurality of parallel light beams incident on an optical element as a subject;
Imaging means for capturing a plurality of emitted light flux images emitted from the optical element;
The emitted light beam images of the plurality of parallel light beams emitted from the optical element, and the plurality of parallel light beams on the same simulation as the plurality of parallel light beams are incident on the ideal optical element on the simulation and are emitted from the ideal optical element. A plurality of simulated exit beam images on the simulation are compared, and the ideal optical element is expressed by a Zernike polynomial using a plurality of relative distances between the plurality of simulated exit beam images and the corresponding exit beam images as data. Computing means for computing and generating a curved surface representing a deviation from the optical surface of
An optical surface evaluation apparatus comprising: The parallel light beam generating means includes a light source, a collimator lens that converts the light beam from the light source into parallel light, and a multi-hole plate that generates a plurality of parallel light beams from the parallel light beams emitted from the collimator lens. The optical surface evaluation apparatus according to claim 7, wherein at least one of the holes of the multi-hole plate has a hole shape different from that of the other holes. A plurality of parallel light beams are generated from a parallel light beam generating means for generating a plurality of parallel light beams, and the light beams are incident on an optical element as a subject,
The emitted light beam images of the plurality of parallel light beams emitted from the optical element, and the plurality of parallel light beams on the same simulation as the plurality of parallel light beams are incident on the ideal optical element on the simulation and are emitted from the ideal optical element. Compare multiple simulated light flux images on the simulation,
Calculating and generating a curved surface by a Zernike polynomial using a plurality of relative distances between each of the simulated emitted light beam images and the corresponding emitted light beam images as data, and evaluating the optical surface of the optical element by the shape of the curved surface; An optical surface evaluation method characterized.

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