WO2023120604A1

WO2023120604A1 - Measuring device, adjusting device, and measuring method

Info

Publication number: WO2023120604A1
Application number: PCT/JP2022/047217
Authority: WO
Inventors: 健司福井; 克誌小林
Original assignee: 京セラ株式会社
Priority date: 2021-12-23
Filing date: 2022-12-21
Publication date: 2023-06-29

Abstract

This measuring device comprises a light source unit, an optical element, and at least one imaging element. The light source unit is configured to emit a plurality of light beams having mutually different directions simultaneously onto a lens under test that is to be measured. The optical element converts the plurality of light beams that have passed through the lens under test and that then converge or diverge after converging. The at least one imaging element receives the plurality of light beams that have been converted.

Description

Measuring device, adjusting device and measuring method

Cross-reference to related applications

This application claims priority from Japanese Patent Application No. 2021-209911 filed on December 23, 2021, and the entire disclosure of this earlier application is incorporated herein for reference.

The present disclosure relates to a measuring device, an adjusting device, and a measuring method.

A wavefront measurement device has been proposed that measures wavefront aberration in order to reduce errors caused by assembly when assembling optical components that include multiple lenses. For example, according to Patent Document 1, a test optical system to be measured is irradiated with light, and the transmitted wavefront of the light transmitted through the test optical system is detected using an imaging device to measure the wavefront. Is going.

JP 2015-55544 A

A measuring device according to the present disclosure includes a light source unit, an optical element, and at least one imaging element. The light source unit is configured to simultaneously irradiate the optical component to be measured with a plurality of light beams having different directions. The optical element converts the plurality of light beams that converge or diverge after convergence after passing through the optical component. The at least one imaging device receives the converted plurality of light beams.

The measurement method of the present disclosure includes a first step, a second step, and a third step. In the first step, the optical component to be measured is simultaneously irradiated with a plurality of light beams having directions different from each other. The second step converts the plurality of light fluxes, which converge or diverge after convergence after passing through the optical component, using an optical element. In the third step, at least one imaging device receives the plurality of converted light beams.

FIG. 1 is a diagram illustrating a schematic configuration example of a measuring device according to an embodiment of the present disclosure. 2 is a diagram showing another configuration of the light source unit in FIG. 1. FIG. 3 is a diagram showing a more detailed configuration of the optical element and wavefront sensor of FIG. 1. FIG. 4 is a diagram showing another configuration of the wavefront sensor of FIG. 1. FIG. 5 is a diagram showing still another configuration of the wavefront sensor of FIG. 1. FIG. FIG. 6A is a plan view showing the structure of a microlens array, which is an example of an optical element. FIG. 6B is a perspective view showing another example of the shape of the microlens. FIG. 6C is a plan view showing a configuration example of another microlens array in which the microlenses of FIG. 6B are arranged. FIG. 6D is a plan view showing still another configuration example of a microlens. FIG. 7A is a diagram showing an example of a pattern in which a plurality of light beams transmitted through a microlens array irradiate an imaging element surface of an imaging element. FIG. 7B is a diagram showing another example of a pattern in which a plurality of light beams transmitted through the microlens array irradiate the imaging element surface of the imaging element. FIG. 8 is a diagram showing an example of a pattern in which one of the plurality of light beams shown in FIG. 7A is irradiated on the surface of the imaging device by the light beam that has passed through the microlens array. FIG. 9 is a diagram showing another pattern of areas on the surface of the imaging device illuminated by a plurality of light fluxes. FIG. 10 is a diagram showing still another pattern of regions on the surface of the imaging device illuminated by a plurality of light fluxes. FIG. 11 is a diagram showing the structure of a diffraction grating, which is an example of an optical element. FIG. 12 is a diagram showing how one of the light beams transmitted through the diffraction grating generates an interference pattern on the surface of the imaging device. FIG. 13 is a diagram showing an example of the configuration of a wavefront sensor using diffraction gratings. FIG. 14 is a diagram for explaining a method of wavefront measurement according to the prior art. FIG. 15 is a diagram for explaining a method of wavefront measurement according to the prior art. FIG. 16 is a diagram for explaining a method of wavefront measurement according to the prior art. FIG. 17 is a diagram for explaining a method of wavefront measurement according to the prior art.

With conventional wavefront measurement devices, it is necessary to move the light source and wavefront sensor when trying to change the image height during wavefront measurement. Therefore, when trying to measure wavefront aberration corresponding to a plurality of image heights, the measurement may take time.

The measurement apparatus and measurement method of the present disclosure measure the transmitted wavefronts at a plurality of different image heights substantially simultaneously for the optical component to be measured.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The figures used in the following description are schematic. The dimensions, ratios, etc. on the drawings do not necessarily match the actual ones.

First, before describing a measuring apparatus according to an embodiment of the present disclosure, a conventional wavefront measuring apparatus 100 used for adjusting a group lens will be described.

FIGS. 14 to 16 show the arrangement of the constituent elements of the apparatus when measuring the wavefront of a light flux that has passed through a lens 120 to be measured by changing the image height using the conventional wavefront measuring apparatus 100. It is a figure explaining. The measuring device 100 includes a light source 111 , a first collimating lens 112 , a second collimating lens 160 and a wavefront sensor 130 .

In FIG. 15 , a diffused light flux emitted from a light source 111 positioned on the optical axis O of the lens 120 to be examined is converted into a parallel light flux centered on the optical axis O by the first collimator lens 112 . be irradiated. In FIGS. 14 and 16, the light beam emitted from the light source 111 which is displaced from the optical axis O is collimated by the first collimating lens 112, and the lens 120 to be inspected is irradiated with the light beam from outside the optical axis O. In FIGS. The light flux irradiated to the lens 120 to be examined is refracted by the refractive power of the lens 120 to be examined when passing through the lens 120 to be examined. The light beam transmitted through the lens 120 to be inspected is converted into a parallel light beam by the second collimator lens 160, and the wavefront is measured by the wavefront sensor 130. FIG.

As shown in FIGS. 14 to 16, when one light source 111 and one wavefront sensor 130 are used, the light source 111 and the wavefront sensor 130 must be moved. That is, it is necessary to move the light source 111 in a direction intersecting the optical axis O, and to move the wavefront sensor 130 to a position conjugate with the light source 111 corresponding to the movement of the light source 111 . For this reason, it takes time to perform wavefront measurement at a plurality of different image heights using the measurement apparatus 100 .

In addition, when the position, orientation, etc. of the lens 120 to be measured are adjusted using the measurement apparatus 100 so as to reduce the transmitted wavefront aberration, the on-axis and off-axis transmitted wavefronts cannot be observed at the same time. Therefore, even if the lens under test 120 is adjusted so as to reduce the aberration of the transmitted wavefront of the on-axis light flux by the arrangement of FIG. 15, the transmitted wavefront of the off-axis light flux measured by the arrangement of FIG. may deteriorate. Moreover, the reverse may also occur in the same manner. Therefore, in the conventional measurement apparatus 100, there is a problem that it is difficult to adjust the lens 120 to be inspected so that a plurality of different image heights have good transmitted wavefronts.

Furthermore, when the lens 120 to be measured is used in an imaging device, the sensor used in the wavefront sensor 130 of the measuring device 100 and the imaging device used in the imaging device are different. Therefore, the transmitted wavefront measured by the measuring device 100 and the transmitted wavefront observed on the imaging device of the imaging device may not necessarily match. Therefore, the measurement result obtained by the measurement apparatus 100 may not match the imaging performance of the imaging apparatus.

Also, as shown in FIG. 17, it is possible to configure the measuring device 100A by combining a plurality of light sources 111a to 111c and a plurality of wavefront sensors 130a to 130c. The measurement apparatus 100A irradiates the lens 120 to be inspected with three light beams in different directions, separates the transmitted light beams by

prisms

170a, 170b, etc., and measures them with three

wavefront sensors

130a, 130b, and 130c, respectively. In FIG. 17, light beams emitted from the

light sources

111a, 111b, and 111c arranged side by side are converted into three parallel light beams in different directions by the first collimating lens 112, and the lens 120 to be inspected is irradiated with the parallel light beams. This method requires three

wavefront sensors

130a, 130b and 130c, resulting in a larger apparatus and higher cost.

The measuring device 1 according to the present embodiment described below solves the above problems and makes it possible to measure the transmitted wavefronts of light beams incident from a plurality of different directions in a short time or substantially simultaneously. In addition, being able to measure substantially simultaneously means being able to measure in parallel or sequentially without changing the arrangement configuration of the apparatus. Being able to measure substantially simultaneously does not mean that the measurement results of the transmitted wavefront are obtained strictly at the same time.

As shown in FIG. 1, the measuring device 1 according to one embodiment of the present disclosure is a device that measures the wavefront of a light flux passing through a test lens 20, which is an optical component to be measured. The measuring device 1 includes a light source section 10 , a wavefront sensor 30 , a computing section 40 and a display section 50 .

The light source unit 10 includes a plurality of

light sources

11a, 11b and 11c and a collimator lens 12. The plurality of

light sources

11a, 11b, and 11c may be collectively referred to as the light source 11. FIG. The plurality of

light sources

11a, 11b, and 11c may include, but are not limited to, LDs (laser diodes) or LEDs (light emitting diodes). A plurality of

light sources

11 a , 11 b , and 11 c emit diffused light beams toward the collimator lens 12 . A plurality of

light sources

11a, 11b, and 11c are arranged side by side in a plane perpendicular to the central ray of the emitted light beam. The number of light sources 11 is not limited to three, and may be two or four or more. For example, a total of 9 light sources 11 can be arranged in a 3×3 matrix, or a total of 25 light sources 11 can be arranged in a 5×5 matrix.

The light source unit 10 does not have a plurality of

light sources

11a, 11b, and 11c, and may be configured by combining one common light source 13, a pinhole array 14, and a collimating lens 12 as shown in FIG. . In this case, the

pinholes

14a, 14b, and 14c provided in the pinhole array 14 transmit the light from the common light source 13 to the lens 20 to be inspected. Each

pinhole

14a, 14b and 14c emits a light beam toward the collimating lens 12, like the

light sources

11a, 11b and 11c in FIG. By configuring in this way, the light source section 10 can be configured at a lower cost than when the

individual light sources

11a, 11b and 11c are provided.

The collimating lens 12 converts the diffused light beams emitted from the

respective light sources

11a, 11b and 11c into parallel light beams. The collimator lens 12 is, for example, a convex lens. A diffused light flux incident on the collimating lens 12 through the optical axis of the collimating lens 12 is emitted in a direction passing through the optical axis of the collimating lens 12 . Diffused light beams passing through the outside of the optical axis of the collimating lens 12 and entering the collimating lens 12 parallel to the optical axis are deflected in the direction of the optical axis of the collimating lens 12 at different angles depending on the position of incidence on the collimating lens 12. . Thereby, the light source unit 10 can simultaneously irradiate the lens 20 to be inspected with a plurality of parallel light beams having different directions.

The configuration of the light source unit 10 is not limited to that shown in FIGS. 1 and 2. For example, instead of each light source 11 of the light source unit 10, the other end of a plurality of optical fibers having one end connected to the light source device may be arranged facing the collimating lens 12 side.

The test lens 20 is the object to be measured by the measuring device 1 . The test lens 20 is composed of one or a plurality of lenses arranged in one direction. In one embodiment, the lens under test 20 is a set of lenses. At least one lens in the plurality of lenses may be adjustable in position and orientation to adjust the transmitted wavefront. In FIG. 1 and subsequent drawings, the lens 20 to be examined is indicated by one rectangle for convenience. In this embodiment, the test lens 20 is assumed to have a positive refractive power. When the lens 20 to be examined has a positive refractive power, the luminous flux transmitted through the lens 20 to be examined becomes convergent light as shown in FIG.

The lens 20 to be examined has an optical axis O. When the optical axes of a plurality of lenses included in the lens 20 to be examined do not match, the optical axis of the lens closest to the wavefront sensor 30 in the lens 20 to be examined may be taken as the optical axis O. The light source unit 10 can be configured such that the optical axis of the collimating lens 12 coincides with the optical axis O, and one light source 11b is positioned on the optical axis. As a result, the luminous flux emitted from the light source 11b becomes an axial luminous flux that irradiates the lens 20 to be examined 20 as a luminous flux about the optical axis O as a luminous flux. In FIG. 1 and the following figures, the on-axis luminous flux is indicated by a thick dashed line to distinguish it from other luminous fluxes. The light beams emitted from the other

light sources

11a and 11c become off-axis light beams. Light fluxes emitted from the other

light sources

11a and 11c are displayed with thin dashed lines.

The wavefront sensor 30 includes an optical element 31 and an imaging element 32 .

The optical element 31 converts a plurality of light fluxes that converge or diverge after convergence after passing through the lens 20 to be examined. For example, the optical element 31 changes the local direction of travel of the light contained in each of the plurality of light beams, and transforms the spatial intensity distribution of the light beams with which the imaging device 32 is irradiated. The optical element 31 is, for example, a microlens array or a diffraction grating, but is not limited to these. In the drawings below, the optical element 31 is shown in a square shape when viewed along the optical axis O, but the shape of the optical element 31 is not limited to this. For example, optical element 31 may be rectangular.

The imaging device 32 is a device that converts an image formed on the imaging device surface 32a into an electric signal. The imaging element 32 converts the electric signal into a digital image signal by an AD conversion circuit and outputs the digital image signal to the arithmetic unit 40 . The imaging device 32 may be either a two-dimensional image sensor including a CCD image sensor (Charge-Coupled Device Image Sensor) and a CMOS image sensor (Complementary MOS Image Sensor). A plurality of photoelectric conversion elements are two-dimensionally arranged on the imaging element surface 32 a of the imaging element 32 . A plurality of photoelectric conversion elements are arranged, for example, in a grid pattern. A plurality of photoelectric conversion elements correspond to pixels of an image captured by the imaging element 32, respectively.

The imaging device 32 receives a plurality of light beams converted by the optical device 31 on the imaging device surface 32a. A plurality of luminous fluxes are received by different regions of the imaging element surface 32a. As the light beams are converted by the optical element 31, the light intensity distribution of each light beam detected by the imaging element surface 32a reflects the wavefront shape of a plurality of light beams having different image heights that have passed through the lens 20 to be inspected. It becomes a thing.

The computing unit 40 acquires from the imaging device 32 the light intensity distributions of the plurality of light beams corresponding to the plurality of image heights formed on the imaging device 32 . Based on the obtained light intensity distribution of each light beam, the calculation unit 40 calculates the transmitted wavefront aberration corresponding to each of the plurality of light beams. The computing unit 40 may be installed in a computer such as a portable information terminal, a PC (Personal Computer), or a workstation. The computing unit 40 includes one or more processors. The processor includes a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor that specializes in specific processing.

The display unit 50 displays the transmitted wavefront aberration corresponding to each of the plurality of light fluxes calculated by the calculation unit 40. The transmitted wavefront aberrations corresponding to multiple beams may be displayed simultaneously or sequentially. The display unit 50 employs any of various displays such as a liquid crystal display (LCD), an organic EL (Electro-Luminescence) display, an inorganic EL display, a field emission display (FED), and the like. I can.

In the wavefront sensor 30, the optical element 31 and the imaging element 32 can be arranged in various ways in relation to the focal plane 33 of the lens 20 to be examined. In the following, along the optical axis O, the side of the lens to be examined 20 as viewed from the imaging device 32 is defined as the front side, and the side of the imaging device 32 as viewed from the lens 20 is defined as the rear side. For example, as shown in FIG. 3, optical element 31 can be positioned in front of focal plane 33 . The imaging element 32 can be positioned behind the focal plane 33 . Also, as shown in FIG. 4 , the optical element 31 and the imaging element 32 can be positioned behind the focal plane 33 . Furthermore, as shown in FIG. 5, the optical element 31 and the imaging element 32 can be located in front of the focal plane 33, which is not shown in FIG. 5 because it overlaps the imaging element 32. FIG.

In any case, the optical element 31 is positioned at a position where the light flux converges or diverges after convergence. In other words, unlike the conventional technology, the wavefront sensor 30 does not employ a configuration in which the light beam is converted into a parallel light beam and then measured by the imaging device 32 . Therefore, unlike the measuring

devices

100, 100A shown in FIGS. 14 to 17, this configuration does not include the second

collimating lenses

160, 160a-160c. If a collimating lens is arranged immediately before the wavefront sensor 30, the collimating lens occupies a certain amount of space. Therefore, it becomes difficult to detect a plurality of luminous fluxes with one imaging device. In the measuring device 1 of the present embodiment, since a plurality of light beams incident on the wavefront sensor 30 are not converted into parallel light beams, one imaging element 32 can be used for detecting a plurality of light beams, making the device simple and inexpensive. Can be configured. In addition, since no collimating lens is arranged, there is an advantage that the arrangement of the apparatus can be made easier and the measurement becomes easier.

For the optical element 31, for example, a microlens array 35 as shown in FIG. 6A can be used. The microlens array 35 is configured by arranging a plurality of circular microlenses 35a in a grid pattern in two mutually orthogonal directions. A gap portion between the plurality of microlenses 35a of the microlens array 35 may be a non-transmissive portion 35b that does not transmit the light flux. Note that the arrangement of the plurality of microlenses 35a is not limited to the form shown in FIG. 6A. For example, the plurality of microlenses 35a may be arranged in a honeycomb pattern.

The outer shape of the microlenses 35a of the microlens array 35 is not limited to circular. For example, the microlens array 35 may be configured by arranging rectangular lenses 35c in a plane as shown in FIG. 6B. The rectangular lens 35c may have a rectangular shape obtained by cutting out a circular convex lens. By arranging the lenses 35c each having a rectangular outer shape, it is possible to configure the microlens array 35 whose entire surface is a transmission region for transmitting the light flux, as shown in FIG. 6C.

Further, the microlenses 35a included in the microlens array 35 are not limited to those using refraction of optical members. The microlens 35a may be composed of a diffraction element. For example, as shown in FIG. 6D, the microlens 35a can be a Fresnel zone plate in which a first ring-shaped portion 35d and a second ring-shaped portion 35e are alternately arranged as concentric rings from the center. The first ring-shaped portion 35d and the second ring-shaped portion 35e may have a structure in which a step is provided in a transparent material so that the transmitted light beams have a phase difference of 180° (π [radian]). can. A Fresnel zone plate is configured to focus the transmitted light beam to a single point. Note that the configuration of the Fresnel zone plate is not limited to that described above. For example, the first ring-shaped portion 35d and the second ring-shaped portion 35e may be configured to be transparent and opaque to the light of the wavelength of the luminous flux, respectively.

The luminous flux incident on each microlens 35a of the optical element 31 forms a point image on the imaging element surface 32a of the imaging element 32 (see FIGS. 7A, 7B, and 8). That is, in FIGS. 3, 4 and 5, when the optical element 31 is the microlens array 35, the optical element 31 and the imaging device 32 are arranged such that the condensing position of each microlens 35a is the imaging device surface of the imaging device 32. 32a. Therefore, when the wavefront sensor 30 has the configuration of FIG. 3, each microlens 35a has a negative refractive power. On the other hand, when the wavefront sensor 30 has the configuration of FIGS. 4 and 5, each microlens 35a has a positive refractive power.

When the optical element 31 is a microlens array 35, the wavefront sensor 30 may be configured as a Shack-Hartmann wavefront sensor. The wavefront sensor 30 can detect the local gradient of the wavefront based on the displacement of the position of the imaging point of each microlens 35a on the imaging element surface 32a from the center point.

In the light source unit 10, when viewed from the direction along the optical axis O, a total of nine light sources 11 are arranged, three each in a first direction and a second direction perpendicular to the first direction, and the wavefront sensor 30 is An example of the configuration shown in FIG. 5 will be described. When the optical axis O is in the horizontal plane, the first direction is, for example, the horizontal direction perpendicular to the optical axis. The second direction is, for example, the vertical direction. In this case, nine light beams are emitted from the light source section 10 .

The nine light beams pass through the lens 20 under test in different directions, are refracted by the microlenses 35a in the microlens array 35, which is the optical element 31, and are received by the imaging device surface 32a of the imaging device 32. As shown in FIG. 7A, each luminous flux passes through a predetermined area of the microlens array 35 determined by the angle of incidence on the lens 20 to be inspected, and is incident on the imaging element surface 32a. Each luminous flux is centered on the point where it intersects the optical axis O on the imaging device 32, and each of the regions spatially divided into a total of nine regions, three each in the first direction and the second direction. Irradiate. In the measuring apparatus 1 of the present embodiment, the wavefront sensor 30 measures the converging or diverging light beams, so that the small diameter portions of the respective light beams can be received without overlapping on the imaging element surface 32a. . Therefore, using the imaging element surface 32a of the single imaging element 32, it is possible to measure wavefronts at a plurality of different image heights.

In FIG. 7A, each light flux passes through different regions of the microlens array 35 without overlapping each other. However, each luminous flux may irradiate different areas on the imaging element surface 32a, and may pass through overlapping areas in the microlens array 35 as shown in FIG. 7B. By doing so, it is possible to measure the wavefront of each light beam that has passed through a wider area of the lens 20 to be inspected.

FIG. 8 shows an enlarged transmission region R1 of the microlens array 35 through which one of the nine light beams is transmitted, and a light receiving region R2 of the imaging element surface 32a through which the light beam is received. Light rays transmitted through each microlens 35a are condensed on the imaging element surface 32a to form an image of a light beam cross section called a heartmanogram 36. FIG.

Based on the heart manogram 36 detected by the imaging device 32, the computing unit 40 computes the center of gravity of the light intensity distribution of each region finely divided by each microlens 35a. In FIG. 8 the center of gravity is represented as a point of the heartmanogram 36 . The computing unit 40 further computes how much the center of gravity position deviates from each reference position on the imaging element surface 32a, and obtains the transmitted wavefront aberration in each light beam cross section.

The calculation unit 40 can calculate PV (Peak To Valley) value, Root Mean Square (RMS) value, Seidel's five aberrations, and/or Zernike's coefficient of the transmitted wavefront by a known method. The calculation unit 40 can display at least one of these transmitted wavefront aberrations on the display unit 50 .

Thereby, the measuring device 1 can simultaneously irradiate the lens 20 under test with light beams from nine different directions, and calculate the transmitted wavefront aberration corresponding to each light beam. Therefore, the measurement apparatus 1 can measure the transmitted wavefronts of light beams incident on the lens 20 under test from a plurality of different directions in a short period of time or substantially simultaneously. Furthermore, the user of the measurement apparatus 1 checks the transmitted wavefront aberration displayed on the display unit 50, and adjusts the wavefront aberrations of the light beams in different directions to reduce the wavefront aberrations of the individual lenses included in the lens 20 to be inspected. lens position and/or orientation can be adjusted. Therefore, by using the measurement device 1, it is possible to adjust the transmitted wavefronts of a plurality of light beams in different directions without moving the light source unit 10 and the wavefront sensor 30. FIG.

The measuring device 1 can also be used when adjusting the position of the subject lens 20 of an imaging device including the imaging device 32 that is actually used. In this case, the measurement apparatus 1 is configured by disposing the optical element 31 between the lens 20 to be examined and the imaging element 32, and moving the imaging element 32 of the imaging apparatus by a predetermined amount from the image plane in the optical axis direction. can do. The user of the measurement apparatus 1 can adjust the positions of the lenses included in the test lens 20 in this state. As a result, the measurement results obtained by the measurement apparatus 1 and the imaging performance of the actually used imaging apparatus are in good agreement with each other.

It should be noted that the number of luminous fluxes irradiating the subject lens 20 in different directions is not limited to nine. For example, the number of beams can be five. For example, in the light source unit 10, when viewed in the direction along the optical axis O, the five light sources 11 can be arranged so as to be positioned at the center of gravity and the four vertices of a square. By doing so, the light source unit 10 can irradiate the lens 20 to be inspected with one axial light flux and four off-axis light fluxes. For example, two off-axis luminous fluxes are incident on the lens 20 to be inspected from directions inclined with respect to the optical axis O in two planes inclined by 45 degrees with respect to the horizontal and vertical directions. In this case, the transmissive area R1 of the microlens array 35 and the light receiving area R2 of the imaging element surface 32a are as shown in FIG. The two planes tilted 45 degrees with respect to the horizontal and vertical directions are the first plane and the second plane.

In addition, in the light source unit 10, when viewed in the direction along the optical axis O, the five light sources 11 can be arranged so as to be positioned at the center of gravity and the center of each of the four sides of the square. By doing so, the light source unit 10 can irradiate the lens 20 to be inspected with one axial light flux and four off-axis light fluxes. For example, two off-axis luminous fluxes are incident on the lens 20 to be inspected from directions inclined with respect to the optical axis O in the horizontal plane and the vertical plane, respectively. In this case, the transmissive area R1 of the microlens array 35 and the light receiving area R2 of the imaging element surface 32a are as shown in FIG. The horizontal plane and the vertical plane are the first plane and the second plane.

Since the area of the imaging element surface 32a is constant, when measuring the transmitted wavefront by irradiating with nine light beams, the number of pixels contributing to the measurement per light beam is smaller than when irradiating with five light beams. Measurement accuracy of wavefront measurement becomes low. On the other hand, when nine light beams are irradiated, the number of image positions to be measured, that is, the number of measurement points increases, so that the aberration distribution of the entire image plane can be grasped. The number of luminous fluxes that irradiate the lens 20 to be examined and the direction of irradiation are determined according to the required performance of the imaging device 32 and the lens 20 to be examined.

In addition to the above advantages, when performing measurement using five light beams in different directions, the number of light sources 11 is reduced, so that the measurement device 1 can be configured at a lower cost and with a simpler configuration than when nine light beams are emitted. can do. 9 and 10, the light receiving regions R2 of the four off-axis light beams are different from each other by 90 degrees, and each light receiving region R2 Equidistant from the center of surface 32a. Here, the center of the imaging element surface 32a is the position where the optical axis O crosses the imaging element surface 32a. Thereby, the measuring apparatus 1 can be configured so as to measure the wavefront at the maximum image height of the lens 20 to be measured using each off-axis light flux.

In the measuring device 1 of FIG. 1, a Talbot interferometer can be used as the wavefront sensor 30 . In that case, the optical element 31 can use a diffraction grating 37 instead of the microlens array 35 . The diffraction grating 37 can be composed of, for example, a plate-like member having two types of translucent regions, a plurality of first regions 37a and a plurality of second regions 37b, as shown in FIG. The first regions 37a and the second regions 37b are, for example, square regions when viewed along the optical axis O, arranged alternately in a first direction and a second direction that are orthogonal to each other. The first region 37a and the second region 37b are configured such that the phases of light transmitted therethrough are different by 180°. The reason why the first region 37a and the second region 37b are configured in this way is to reduce the zero-order diffracted light.

When the optical element 31 is the diffraction grating 37, the wavefront sensor 30 can employ any of the configurations shown in FIGS. A case where the wavefront sensor 30 is configured as shown in FIG. 5 will be described as an example. As shown in FIG. 12, one of the light beams transmitted through the lens 20 to be inspected is diffracted by the transmission region R1 of the diffraction grating 37 and received by the light receiving region R2 of the imaging device surface 32a of the imaging device 32. FIG. Due to the diffraction action of the diffraction grating 37, the light flux forms a diffraction pattern on the imaging element surface 32a. The diffraction pattern is distorted by the transmitted wavefront aberration of the light flux that has passed through the lens 20 to be inspected. Wavefront aberration can be calculated by measuring the distortion of this diffraction pattern.

The calculation unit 40 calculates the transmitted wavefront aberration corresponding to each light flux based on the diffraction pattern of each light flux acquired by the imaging device 32 . The calculation unit 40 analyzes the diffraction pattern using Fourier transform and inverse Fourier transform. As a result, the calculation unit 40 can calculate various transmitted wavefront aberrations in the same manner as when the microlens array 35 is used as the optical element 31 .

When the diffraction grating 37 is used as the optical element 31, the wavefront sensor 30 can adopt the configuration shown in FIG. This is obtained by arranging a spatial filter 38 on the focal plane 33 in the configuration of the wavefront sensor 30 shown in FIG. The spatial filter 38 is configured to block diffracted light of some orders from the diffracted light of the diffraction grating 37 and selectively transmit other diffracted lights of some orders. For example, the spatial filter 38 may be configured to block 0th-order diffracted light and transmit ±1st-order diffracted lights, as shown in FIG. Thereby, the optical element 31 can selectively detect the portion of the light that contributes to the calculation of the wavefront aberration.

As described above, even when the diffraction grating 37 is used as the optical element 31, the transmitted wavefronts at a plurality of different image heights of the lens 20 to be measured can be measured simultaneously in a short time or practically. . Moreover, the light source 11 and the wavefront sensor 30 do not need to be moved in order to measure the transmitted wavefront at a plurality of image heights.

Although the above embodiments have been described as representative examples, it is obvious to those skilled in the art that many modifications and substitutions can be made within the spirit and scope of the present invention. Therefore, the present invention should not be construed as limited by the above-described embodiments and examples, and various modifications and/or modifications are possible without departing from the scope of the claims. For example, it is possible to combine a plurality of configuration blocks described in the embodiments and examples into one, or divide one configuration block.

In addition, the present disclosure includes a measurement method performed by the measurement device 1. This measurement method includes a first step, a second step, and a third step. The first step is to simultaneously irradiate the lens 20 to be inspected with a plurality of light beams having different directions. The second step is a step of converting a plurality of light fluxes, which converge or diverge after convergence after passing through the lens 20 to be examined, by the optical element 31 . The third step is a step of receiving the plurality of converted light beams by the imaging element 32 . By this measuring method, the same effects as those described for the measuring device 1 can be obtained.

Further, the measurement apparatus 1 of the present disclosure may be configured as an adjustment apparatus by adding an adjustment unit that adjusts the position and orientation of the lens 20 (optical component) to be inspected.

The optical components are not limited to those with positive refractive power. Optical components include, for example, those having an afocal system that emits an incident parallel light beam as a parallel light beam. In that case, by arranging a convex lens on the exit side of the afocal system to convert it into a convergent system, measurement by the measuring apparatus 1 of the present disclosure becomes possible.

Reference Signs List 1 measuring device 10

light source section

11a, 11b, 11c light source 12 collimating lens 13 common light source 14

pinhole array

14a, 14b, 14c pinhole 20 lens to be inspected (optical component)
30 wavefront sensor 31 optical element 32 imaging element 32a imaging element surface 33 focal plane 35 microlens array 35a microlens 36 heartmanogram 37 diffraction grating 37a first area 37b second area 38 spatial filter 40 arithmetic unit 50 display unit O optical axis R1 transmission region R2 light reception region

Claims

a light source unit configured to simultaneously irradiate an optical component to be measured with a plurality of light beams in different directions;
an optical element that converts the plurality of light beams that converge or diverge after convergence after passing through the optical component;
and at least one imaging device that receives the converted plurality of light beams.
The measuring device according to claim 1, wherein the optical element is a diffraction grating or a microlens array.
2. The measuring apparatus according to claim 1, wherein the optical element is a diffraction grating, and further comprises a spatial filter that selectively transmits a portion of the diffracted light of orders of the diffracted light from the diffraction grating.
3. The plurality of light beams include a light beam that passes on the optical axis of the optical component and irradiates the optical component, and a light beam that irradiates the optical component from outside the optical axis of the optical component. 4. The measuring device according to any one of 1 to 3.
The plurality of light beams are five light beams, and the light beams irradiated to the optical component from off-axis of the optical axis extend from the direction of the optical axis to the in-plane direction of the first surface with the optical axis interposed therebetween. 5. The light beam according to claim 4, comprising two light beams that are inclined and two light beams that are inclined from the direction of the optical axis to the in-plane direction of the second surface perpendicular to the first surface across the optical axis. measuring device.
After being converted by the optical element, the plurality of light beams are centered on the point on the optical axis on the imaging element, and are directed in a first direction and a second direction perpendicular to the first direction. 5. The measuring device according to claim 4, wherein the nine light beams irradiate nine regions arranged in a matrix.
a calculation unit for calculating a transmitted wavefront aberration corresponding to each of the plurality of light beams from the light intensity distribution of the plurality of light beams detected by the imaging device; The measuring device according to any one of claims 1 to 6, further comprising a display section for simultaneously displaying the corresponding transmitted wavefront aberrations.
The transmitted wavefront aberration displayed on the display unit is represented by at least one of a PV (Peak To Valley) value, an RMS (Root Mean Square) value, Seidel's five aberrations, and a Zernike coefficient of the transmitted wavefront. , the measuring device according to claim 7.
a measuring device according to any one of claims 1 to 8;
and an adjustment unit that adjusts the position and orientation of the optical component.
a first step of simultaneously irradiating an optical component to be measured with a plurality of light beams having different directions;
a second step of converting the plurality of light fluxes, which converge or diverge after convergence after passing through the optical component, with an optical element;
and a third step of receiving the converted plurality of light beams by at least one imaging device.