JP2014128365A - Optical wave front measuring device and optical wave front measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To distinguish from which micro lens a light-condensing point is even when the light-condensing point is emitted to a CCD sensor area corresponding to a neighboring micro lens.SOLUTION: An aberration measuring device includes: dividing means that has a plurality of dividing regions for dividing return light from an object to be inspected into a plurality of different lights and is configured so that the property of at least one dividing region of the plurality of dividing regions is different from the property of the other dividing regions; detection means for detecting positions and shapes of a plurality of irradiation regions irradiated with the plurality of different lights respectively; determination means for determining a dividing region corresponding to each of the plurality of irradiation regions on the basis of the detected shape; and acquisition means for acquiring an inclination of the plurality of different lights for each of the plurality of dividing regions on the basis of the determined dividing region and the detected position. The aberration is determined based on the acquired inclination.

Description

  The present invention relates to aberration measurement of an optical wavefront using a Shack-Hartmann sensor.

  Optical wavefront aberration measurement covers a wide range of fields, from industrial fields such as inspection of optical elements to highly academic fields such as adaptive optics (AO) in large terrestrial astronomical telescopes and medical fields such as ophthalmic diagnosis. It is applied in.

  As a typical apparatus for measuring the aberration of the light wavefront, there is a Shack-Hartmann sensor. The Shack-Hartmann sensor is a device including a two-dimensional image pickup device such as a two-dimensional microlens array that divides an optical wavefront and a CCD sensor placed on a focal plane of the microlens of the microlens array. The light wavefront divided by the two-dimensional microlens array is focused on the CCD sensor by individual microlenses. When the original light wavefront is an ideal plane wave and is directly incident on the Shack-Hartmann sensor, each focal point is located at the center of the CCD sensor area corresponding to the projected area of the microlens. When the light wavefront has a local inclination due to aberration, the divided light is collected at a shifted position. By comparing the focal position at the ideal wavefront with no aberration and the focal position where the wavefront with aberration is connected, the local tilt of the optical wavefront can be measured. It is possible to calculate. This method is less affected by disturbance because it does not use light interference, and can be used even in an environment where noise such as vibration and sound exists.

  One of the reasons why the Shack-Hartmann sensor is widely used in ophthalmic aberration measurement in ophthalmology, which is an application field of optical wavefront aberration measurement, is that it has resistance to disturbance as described above. In particular, scanning laser ophthalmoscopes (SLOs) equipped with AO that measure ocular aberrations in real time and cancel the aberrations, including equipment in research institutions such as universities and prototypes in clinical trials, The Shack-Hartmann sensor is widely used for aberration measurement.

  A problem in measuring the aberration of the light wavefront using the Shack-Hartmann sensor is precisely associating which condensing point on the CCD sensor is collected by which microlens. In particular, when the aberration of the light wavefront becomes large or the aberration of the light wavefront becomes complicated, when the condensing point is irradiated to the CCD sensor area corresponding to the adjacent microlens, which condensing point is May be indistinguishable.

  Therefore, in order to correctly associate the microlens and the focal point, the microlens and the focal point are associated by changing the pitch of the microlens array and measuring the aberration of the light wavefront in advance. This is disclosed in Patent Document 1.

US Pat. No. 6,750,957

However, in this method, there is a possibility of erroneous detection when the condensing points from adjacent microlenses are condensed at positions opposite to each other. Moreover, when the condensing points from adjacent microlenses overlap each other, it becomes impossible to distinguish which condensing point.
In view of the above, an object of the present invention is to distinguish between the condensing points even when the condensing points are irradiated to the CCD sensor region corresponding to the adjacent microlens.

The aberration measuring apparatus according to the present invention is
An aberration measuring device that measures the aberration of the return light from the inspection object irradiated with the measurement light,
A dividing unit configured to have a plurality of divided areas that divide the return light into a plurality of lights, and the characteristics of at least one of the plurality of divided areas are different from the characteristics of the other divided areas; ,
Detecting means for detecting positions and shapes of a plurality of irradiation regions irradiated with each of the plurality of lights;
Determining means for determining a divided region corresponding to each of the plurality of irradiation regions based on the detected shape;
Obtaining means for acquiring inclinations of the plurality of lights for each of the plurality of divided regions based on the determined divided region and the detected position;
The aberration is measured based on the acquired tilt.

  According to the present invention, it has a plurality of divided regions (for example, a plurality of optical members such as a plurality of microlenses) that divide the return light into a plurality of light, and at least one of the plurality of divided regions. The characteristics (for example, optical characteristics such as refractive power) are configured to be different from the characteristics of other divided regions. Thereby, even when the condensing point is irradiated to the CCD sensor region corresponding to the adjacent microlens by using the shape of the plurality of irradiation regions (for example, the plurality of condensing points) irradiated with each of the plurality of lights. A divided region corresponding to each of the plurality of irradiation regions can be determined. For this reason, it is possible to distinguish which irradiation region.

It is a schematic diagram of the structural example of the fundus imaging device by SLO provided with the adaptive optics system concerning a 1st embodiment. It is a schematic diagram which shows the structure of the Shack-Hartmann sensor which concerns on 1st Embodiment. It is a schematic diagram which shows an example of the signal (Hartmann image) of the Shack-Hartmann sensor which concerns on 1st Embodiment. It is a flowchart for demonstrating operation | movement of the Shack-Hartmann sensor which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of the Shack-Hartmann sensor which concerns on 2nd and 4th embodiment. It is a flowchart for demonstrating operation | movement of the Shack-Hartmann sensor which concerns on 3rd Embodiment. It is a schematic diagram which shows the structure of the Shack-Hartmann sensor which concerns on 3rd Embodiment. It is a flowchart for demonstrating operation | movement of the Shack-Hartmann sensor which concerns on 4th Embodiment. It is a flowchart for demonstrating operation | movement of the Shack-Hartmann sensor which concerns on 4th Embodiment.

  According to this embodiment, it has a plurality of divided areas (for example, a plurality of optical members such as a plurality of microlenses) that divide the return light into a plurality of lights, and at least one of the plurality of divided areas. (For example, optical characteristics such as refractive power) are different from those of other divided regions. Thereby, even when the condensing point is irradiated to the CCD sensor region corresponding to the adjacent microlens by using the shape of the plurality of irradiation regions (for example, the plurality of condensing points) irradiated with each of the plurality of lights. A divided region corresponding to each of the plurality of irradiation regions can be determined. For this reason, it is possible to distinguish which irradiation region.

  Note that optical elements of the human eye (cornea, lens, etc.) generally have aberrations, and when photographing the fundus at the photoreceptor level to detect early signs of disease in the microcirculation of the fundus, It is known that the fundus image is blurred due to the influence. In fundus imaging at the photoreceptor cell level using AOSLO, the light for imaging that has passed through the optical elements of the eye undergoes aberrations due to the aberration of the eye. In particular, when photographing a human eye with complex aberrations such as a keratoconus that deforms so that the cornea protrudes, the condensing point on the CCD sensor of the Shack-Hartmann sensor used for measuring the aberration of the light wavefront is adjacent. And a phenomenon in which a plurality of lights cross each other. In this case, it is impossible to correctly associate the focal point with the microlens, resulting in an erroneous calculation result of the light wavefront aberration.

  Hereinafter, modes for carrying out the present invention will be described. However, the present invention is not limited by the configuration of the following embodiment.

[First Embodiment: Optical means in which optical characteristics of adjacent divided regions are different]
The configuration of the fundus imaging apparatus to which the aberration measurement apparatus according to the first embodiment is applied will be described with reference to FIG. FIG. 1 is a schematic diagram of a configuration example of a fundus imaging apparatus using an SLO including the adaptive optical system according to the first embodiment. The fundus imaging apparatus according to the present embodiment applies an eye as an example of an object to be inspected, corrects an aberration generated in the eye with AO, and images the fundus of the eye. In addition to the subject's eye, the subject may be anything as long as it is a subject, and is a concept that includes, for example, human skin and internal organs. In addition to the fundus imaging apparatus, the aberration measurement apparatus according to the present embodiment is applicable to any imaging apparatus such as an endoscope. In addition, the aberration measurement apparatus according to the present embodiment is an apparatus that does not use a wavefront correction device that is an example of an aberration correction unit to be described later, for example, before performing surgery to remove the cornea with a laser or the like for refraction correction. It is applicable also to the apparatus for measuring the shape of this.

  In FIG. 1, 101 is a light source, and an SLD light source (Super Luminescent Diode) having a wavelength of 840 nm was used. Although the wavelength of the light source 101 is not particularly limited, about 800 to 1500 nm is suitably used for fundus imaging in order to reduce glare and maintain resolution of the subject. In this embodiment, an SLD light source is used, but a laser or the like can also be used. In the present embodiment, the light sources for fundus imaging and wavefront measurement are shared, but each may be a separate light source and combined in the middle of the optical path.

  First, light emitted from the light source 101 passes through the single mode optical fiber 102 and is irradiated as parallel light (measurement light 105) by the collimator 103. The irradiated measurement light 105 is transmitted through the light splitting unit 104 formed of a beam splitter and guided to the AO. The AO includes a light splitting unit 106, a Shack-Hartmann sensor 115, a wavefront correction device 108, and reflection mirrors 107-1 to 107-4 for guiding light to them. Here, the reflection mirrors 107-1 to 107-4 are installed so that at least the pupil of the eye 111, the wavefront sensor 115, and the wavefront correction device 108 are optically conjugate. Further, as the light splitting unit 106, a beam splitter is used in the present embodiment. The measurement light 105 transmitted through the light splitting unit 106 is reflected by the reflection mirrors 107-1 and 107-2 and enters the wavefront correction device 108. The measurement light 105 reflected by the wavefront correction device 108 is emitted to the reflection mirror 107-3. Here, in this embodiment, a liquid crystal spatial phase modulator is used as the wavefront correction device 108. Another example of the wavefront correction device 108 is a variable shape mirror. The variable shape mirror can change the light reflection direction locally, and various types of mirrors have been put into practical use.

  In FIG. 1, the light reflected by the reflection mirrors 107-3 and 4 is scanned one-dimensionally or two-dimensionally by the scanning optical system 109. In this embodiment, two galvano scanners for main scanning and sub scanning are used for the scanning optical system 109. A resonant scanner can also be used for main scanning of the scanning optical system 109 for higher-speed imaging. In order to arrange each scanner in the scanning optical system 109 at an optically conjugate position, there may be an apparatus configuration using an optical element such as a mirror or a lens between the scanners.

  Further, the measurement light 105 scanned by the scanning optical system 109 is irradiated to the eye 111 through the eyepiece lenses 110-1 and 110-2. The measurement light applied to the eye 111 is reflected or scattered by the fundus. By adjusting the positions of the eyepieces 110-1 and 110-2, it is possible to perform optimal irradiation in accordance with the diopter of the eye 111. Here, a lens is used for the eyepiece, but a spherical mirror or the like may be used.

  In addition, the reflected light reflected or scattered from the retina of the eye 111 travels in the opposite direction along the incident path, and a part of the light reflected by the light dividing unit 106 enters the Shack-Hartmann sensor 115. .

  Here, the Shack-Hartmann sensor will be described with reference to FIG. FIG. 2 is a schematic diagram of the Shack-Hartmann sensor. FIG. 2A is a schematic diagram of a cross section of the Shack-Hartmann sensor, and shows how a plurality of lights obtained by dividing the return light by the microlens array are irradiated onto the CCD sensor. FIG. 2B shows a state viewed from the position indicated by AA ′ in FIG. 2A, and shows a state in which the microlens array 132 includes a plurality of microlenses 133. It is a thing. The wavefront is divided by the microlens array 132, and each minute wavefront 134 is condensed on the focal plane 135 on the CCD sensor 133.

  As shown in FIG. 3A, the signal 151 (also referred to as a Hartmann image) of the Shack-Hartmann sensor is a two-dimensional array of condensing points 152 of the micro wavefront 134 divided by the microlens 133. It becomes. When there is no aberration in the optical wavefront 131, the focal point 152 comes to the back center of the corresponding microlens 133. This position is stored in the storage area of the AO control unit 116 as a reference position. When there is an aberration in the light wavefront 131, the condensing point 152 comes to a position shifted from the back center of the corresponding microlens 133. The difference between this position and the reference position is calculated for all the condensing points 152. This value represents the inclination of the minute wavefront 134 divided by the microlens 133.

  The Shack-Hartmann sensor 115 is connected to the AO control unit 116 and transmits a received signal to the AO control unit 116. The wavefront correction device 108 is also connected to the AO control unit 116 and performs modulation instructed by the AO control unit 116. The AO control unit 116 calculates a phase modulation amount for correcting to a wavefront having no aberration based on the wavefront acquired from the measurement result of the Shack-Hartmann sensor 115 and modulates the wavefront correction device 108 as such. To command. The measurement of the wavefront and the instruction to the wavefront correction device are repeatedly processed, and feedback control is performed so that the optimum wavefront is always obtained.

  The Shack-Hartmann sensor is an example of an aberration measuring unit, and a dividing unit that divides the return light from the inspection object irradiated with the measurement light into a plurality of lights, and the position and size of the region irradiated with the plurality of lights. Any device may be used as long as it is configured by detecting means for detecting the height. Here, the dividing means may be, for example, a mask having a plurality of holes in addition to an optical member composed of a plurality of optical elements such as a lens array. The dividing means may be a means for time division by moving a single mask (or a single lens) two-dimensionally within a range corresponding to the size of the detecting means in addition to the space dividing member. good.

  Here, in the case of an optical wavefront having complicated aberrations, the condensing point on the focal plane of the Shack-Hartmann sensor overlaps with an adjacent condensing point, making it impossible to distinguish the two condensing points. And the micro lens cannot be associated with each other, and a situation in which the aberration of the optical wavefront cannot be measured correctly occurs.

  FIG. 3 (b) shows a signal 153 of a Shack-Hartmann sensor including a condensing point 154 having two overlaps. Since the two condensing points 154 having an overlap have continuous intensity distribution, they cannot be detected as two condensing points in the generally used centroid calculation.

(Optical means having non-rotationally symmetric power)
The Shack-Hartmann sensor according to the present embodiment uses a lens array in which lenses and lenses having rotationally symmetric refractive power are alternately arranged as an example of optical means having non-rotationally symmetric refractive power. Even when a plurality of condensing points, which are examples of a plurality of irradiation areas of a plurality of light beams that irradiate the focal plane 135, which is an example of a sensor surface of the Shack-Hartmann sensor, overlap with adjacent condensing points, Can be correctly associated with the microlens. Here, the non-rotationally symmetric refractive power means that the refractive surface and refractive index distribution of the optical system are not rotationally symmetric with respect to the optical axis, and a lens having a non-rotationally symmetric refractive power is, for example, cylindrical. A lens, a toric lens, a gradient index (GRIN) lens, a free-form surface lens, and the like. The cylindrical lens is a lens in which one of the two directions does not collect light.

  Here, FIG. 2C shows a configuration of a Shack-Hartmann sensor using a microlens array 137 including a toric microlens 139 as a microlens having non-rotationally symmetric refractive power. FIG. 2D is a diagram showing a state viewed from the position indicated by B-B ′ in FIG. In FIG. 2C, the microlens 138 forms a condensing point on the focal plane 135. In the plane including the central axis and the x-axis of the toric microlens 139, the light is condensed in front of the focal plane 135, and the plane including the central axis of the toric microlens 139 and the y-axis. Inside, the microlens 138 and the microlens 139 have the same focal length and are focused on the focal plane 135. FIG. 3C shows a signal 155 of the Shack-Hartmann sensor that includes two overlapping condensing points 156 in the Shack-Hartmann sensor using the microlens array 137 shown in FIG. ing. When a mask with a plurality of holes is used instead of an optical member made up of a plurality of optical elements such as a lens array according to this embodiment, the shapes of adjacent masks may be different. preferable. Thereby, the condensing point from which mask can be distinguished from the shape of the condensing point.

(If there is a lost irradiation area among multiple irradiation areas)
Next, a procedure for separating the overlapping condensing point 156 as two condensing points and correctly associating the condensing point with the microlens 138 and the toric microlens 139 of the microlens array 137 will be described with reference to FIG. Will be described. FIG. 4 is a flowchart for explaining the operation of the Shack-Hartmann sensor according to the first embodiment.

  First, in step S101, measurement by the Shack-Hartmann sensor 115 is started. Further, in step S102, information on the condensing point shape of the microlens array 137 is read and stored in the storage area. The information on the condensing point shape is information on the shape such as the position of the toric microlens 139 in the microlens array 138 and the lengths of the long and short diameters of the condensing points by the toric microlens 139. .

  In step S103, the signal 155 of the Shack-Hartmann sensor is acquired. In step S104, the intensity distribution of the signal 155 of the Shack-Hartmann sensor is measured. In step S105, the information on the condensing point shape of the microlens array 137 is compared with the intensity distribution of the signal 155 of the Shack-Hartmann sensor. A condensing point that has been detected as a point, or cannot be detected due to vignetting caused by an optical element in the optical path, or a decrease in the amount of light due to scattering or absorption (hereinafter referred to as a lost condensing point) Guess).

  In step S106, it is determined whether or not to calculate the lost condensing point. As a criterion for determining whether or not to calculate the lost condensing point, there is no missing condensing point, or all the condensing points that are lost are determined in the procedure from step S107 to step S111. It is mentioned whether it was examined. When calculating the lost condensing point, the process proceeds to step S107.

  In step S107, the missing condensing point is selected. In step S108, the vicinity of the lost condensing point is searched, whether the signal intensity in the vicinity of the lost condensing point is significantly high, and the vicinity of the lost condensing point. Check if the envelope changes significantly in the signal.

  In step S109, based on the result of step S108, it is determined whether or not the two focal points have an overlap. If it is determined that the two focal points do not overlap, the process moves to step S112. If it is determined that the two condensing points have an overlap, the process proceeds to step S110, and the two condensing points having an overlap are analyzed. Here, in step S110, a fitting function including undetermined parameters such as the center position and peak intensity of the condensing point is obtained from the condensing point shape information of the microlens array, and the two condensing points are overlapped. A method of obtaining the center position and peak intensity of the condensing point by fitting the shape of the point is used.

  Further, based on the result of step S110, in step S111, the two condensing points 156 having the overlap are associated with the respective microlenses, and the center of gravity of each of the two condensing points 156 is calculated. Move. Note that the association may be performed after the center of gravity is calculated. Then, the procedure from step S106 to step S111 is repeated until it is determined in step S106 that the lost condensing point is not calculated.

  If it is determined in step S106 that the lost condensing point is not calculated, the process proceeds to step S112. In step S112, a centroid calculation is performed on a condensing point that has not been subjected to the centroid calculation among the plurality of condensing points. Specifically, the calculation of the center of gravity of the condensing points other than the remaining condensing points is performed except for the condensing point whose center of gravity has been calculated before step S112. Next, the process proceeds to step S113, and using the result of the center of gravity calculation obtained up to step S113, a plurality of light gradients are obtained for each of the plurality of divided regions (for each microlens), and the light wavefront is calculated. Do. For the calculation of the light wavefront, fitting of basis functions by the least square method or two-dimensional integration is preferably used. In step S114, the measurement of the light wavefront by the Shack-Hartmann sensor is terminated.

  As an example other than using a single toric microlens 139, as shown in FIG. 2E, a microlens array 140 including a plurality of microlenses 141 and a plurality of toric microlenses 142 is used. May be. FIG. 2F is a diagram showing a state viewed from the position indicated by C-C ′ in FIG. FIG. 3D shows the signal intensity 157 of the Shack-Hartmann sensor using the microlens array 140. The signal intensity 157 of the Shack-Hartmann sensor includes two condensing points 158 that overlap. Also in the signal intensity 157 of the Shack-Hartmann sensor, the light wavefront can be calculated for the condensing point 158 having an overlap according to the procedure from step S101 to step S114.

  In the Shack-Hartmann sensor using the microlens array 140, when the condensing points by a plurality of microlenses having the same focal length overlap, it is impossible to correctly associate the condensing points with the microlenses in step S110. For this reason, it is desirable to exclude the plurality of condensing points from the calculation target in the steps after step S110.

  As described above, according to the present embodiment, when measuring a light wavefront having complicated aberrations, even when the condensing point on the focal plane of the Shack-Hartmann sensor overlaps with an adjacent condensing point, the condensing point is correctly obtained. Can be associated with the microlens, and the aberration of the light wavefront can be measured correctly.

[Second Embodiment: Optical means including a lens having a surface whose refractive power is not rotationally symmetric]
Next, a second embodiment will be described with reference to FIGS. 5 (a) and 5 (b). FIGS. 5A and 5B are schematic views showing the configuration of the Shack-Hartmann sensor according to the second embodiment. The microlens array of the Shack-Hartmann sensor according to the present embodiment includes a lens having a surface whose refractive power is not rotationally symmetric, and microlenses having different refractive powers are alternately arranged. The basic device configuration according to this embodiment is the same as that of the first embodiment.

  First, here, that the refractive power has a non-rotationally symmetric surface means that there is a surface where the refractive surface of the optical system is not rotationally symmetric with respect to the optical axis, and the lens whose refractive power has a non-rotationally symmetric surface. For example, it means a cylindrical lens or a toric lens.

  As shown in FIG. 5, as a microlens array including a lens having a surface whose refractive power is not rotationally symmetric, a cylindrical lens 167 is disposed in the vicinity of the microlens array 163 in which the microlenses 164 are arranged two-dimensionally. Further, a lens in which a cylindrical lens 168 is disposed in the vicinity of the cylindrical lens 167 is used. FIG. 5A is a diagram showing a state viewed from the position indicated by D-D ′ in FIG.

  Desirably, the cylindrical lenses 167 and the cylindrical lenses 168 are arranged every other row of the microlenses 164 in the microlens array 163. Further, a plurality of cylindrical lenses having different focal lengths may be used as the cylindrical lens 167, and a plurality of cylindrical lenses having different focal lengths may be used as the cylindrical lens 168.

  FIG. 3E shows a signal 159 of the Shack-Hartmann sensor including two condensing points 160 having an overlap in the Shack-Hartmann sensor using the microlens array 163 shown in FIG. .

  The procedure of separating the condensing point 160 having the overlap of the Shack-Hartmann sensor of FIG. 3E as two condensing points and correctly associating the condensing point with the microlens of the microlens array is as shown in FIG. Since this is the same as step S101 to step S114 in the flowchart, description thereof is omitted.

  In the present embodiment, even in the case where a plurality of micro wavefronts 165 condensed at different focal lengths by the microlens 163, the cylindrical lens 167, and the cylindrical 168 have a plurality of overlaps, in step S110, a plurality of condensing points are applied. Thus, by performing the same procedure as in the first embodiment, it is possible to associate the focal point with the microlens. That is, a fitting function including undetermined parameters such as the center position and peak intensity of the condensing point is obtained from the information on the condensing point shape of the microlens array, and the shape of the condensing point where multiple condensing points overlap is fitted. By doing so, the center position and peak intensity of the condensing point can be obtained.

  As described above, according to the present embodiment, when measuring a light wavefront having complicated aberrations, even when a plurality of condensing points on the focal plane of the Shack-Hartmann sensor are overlapped, the condensing point and the microscopic point are correctly displayed. Lenses can be associated with each other, and the aberration of the light wavefront can be measured correctly.

[Third embodiment: Modulating one of a plurality of lights from adjacent divided regions]
Next, a third embodiment will be described with reference to FIGS. FIG. 6 is a flowchart for explaining the operation of the Shack-Hartmann sensor according to the third embodiment. FIG. 7 is a schematic diagram showing the configuration of the Shack-Hartmann sensor according to the third embodiment. In this embodiment, the position of the focal point on the focal plane 135 of the Shack-Hartmann sensor 115 is changed by spatial phase modulation using the wavefront correction device 108, and the focal point on the focal plane 135 of the Shack-Hartmann sensor is changed. Even when they overlap with adjacent condensing points, the condensing points can be correctly associated with the microlenses, and the aberration of the light wavefront 171 can be correctly measured. The basic device configuration according to this embodiment is the same as that of the first embodiment.

  FIG. 7A is a schematic diagram in which the light wavefront 171 is divided by the microlens 133 of the microlens array 132. FIG. 7C schematically shows part of the signal of the Shack-Hartmann sensor obtained in FIG.

  The micro wavefront 172 and the microwavefront 173 obtained by dividing the optical wavefront 171 are detected as two condensing points 175 having an overlap due to the aberration of the optical wavefront 171.

  Therefore, the spatial phase modulation of the tilt is applied to the minute wavefront 172 and the minute wavefront 173 using the wavefront correction device 108. FIG. 7B shows the optical wavefront 174 after applying the spatial phase modulation of the tilt by the wavefront correction device 108 to the original optical wavefront 175. As shown in FIG. 7D, the two condensing points 176 that have been overlapped by the spatial phase modulation become separated condensing points 177-1 and 177-2.

  In the flowchart of FIG. 6, steps S101 to S109 are the same as those in the first embodiment, and a description thereof will be omitted. In step S210, the two microlens wavefront correction devices 108 are used to apply spatial phase modulation of inclination to the microwavefront 172 and the microwavefront 173.

  In step S211, the center of gravity of the two condensing points 177-1 and 177-2 is calculated for the separated condensing point 177 in consideration of the amount of inclination given by the spatial phase modulation amount.

  In addition, since the procedure after step S112 is the same as that of the first embodiment, the description thereof is omitted.

  In this embodiment, the case where two adjacent condensing points have an overlap has been described. However, in the case where a plurality of condensing points have an overlap, the spatial phase modulation of the slope is similarly applied and separated. Considering the amount of inclination given by the spatial phase modulation amount with respect to the condensing point, by performing the centroid calculation, it is possible to correctly associate the condensing point with the microlens.

  Further, in the present embodiment, the case where two adjacent condensing points are overlapped has been described. However, the spatial phase modulation of the inclination is similarly applied to the case where a plurality of lights intersect to separate the condensing points. By taking the center of gravity calculation in consideration of the amount of inclination given by the spatial phase modulation amount, it is possible to correctly associate the focal point with the microlens.

  As described above, according to the present embodiment, when measuring a light wavefront having complicated aberrations, even when the condensing point on the focal plane of the Shack-Hartmann sensor overlaps with an adjacent condensing point, the condensing point is correctly obtained. Can be associated with the microlens, and the aberration of the light wavefront can be measured correctly.

[Fourth Embodiment: When a Focusing Point is in an Area Corresponding to an Adjacent Division Area]
The fourth embodiment will be described with reference to FIGS. 5C, 5D, 8 and 9. FIG. In the present embodiment, even when there is a condensing point corresponding to the predetermined lens in the CCD sensor region corresponding to the lens adjacent to the predetermined lens, the plurality of condensing points and the microlenses are correctly associated with each other. is there. The basic device configuration according to this embodiment is the same as that of the first embodiment.

  Note that FIG. 5C shows a situation in which a microlens array 140 including a microlens 141 and a toric microlens is used as in FIG. 2E, and the light wavefront 166 having aberration is irradiated. It is a schematic diagram. FIG. 5D is a view showing a state viewed from the position indicated by E-E ′ in FIG. 8 and 9 are flowcharts for explaining the operation of the Shack-Hartmann sensor according to the fourth embodiment. FIG. 3F shows a signal 161 of the Shack-Hartmann sensor including two condensing points 162-1 and 162-2 where two lights intersect. Note that steps S101 to S105 in FIG. 8 are the same as those in the first embodiment, and a description thereof will be omitted.

  In step S306, it is determined whether or not a plurality of lights intersect and there is a condensing point corresponding to the predetermined lens in the CCD sensor region corresponding to the lens adjacent to the predetermined lens. As a reference for determining whether or not there is a condensing point, information on the shape such as the length of the long and short diameters of the condensing point by the microlens 141 and the toric microlens 142 of the microlens array 140 read in step S102. Is used to compare the shape and arrangement of the expected condensing point with the shape of the condensing point of the signal 161 of the Shack-Hartmann sensor. Whether it is different from the shape and arrangement. For example, the major axis and the minor axis of the beam diameter may be detected for each condensing point, and it may be checked whether the arrangement is expected from the arrangement of the microlens 141 and the toric microlens 142 of the microlens array 140.

  In step S306, when it is determined that there is a condensing point corresponding to the predetermined lens in the CCD sensor region corresponding to the lens adjacent to the predetermined lens, in step S307, the two light collections where the two lights intersect each other. The light spots 177-1 and 177-2 and the microlens 133 are correctly associated with each other, and the center of gravity calculation of the two condensing points 177-1 and 177-2 is performed. Of course, the association may be performed after the center of gravity is calculated.

  If it is determined in step S306 that there is no condensing point corresponding to the predetermined lens in the CCD sensor region corresponding to the lens adjacent to the predetermined lens, the process proceeds to step S112. In addition, after step S307, the process proceeds to step S112. Since step S112 and subsequent steps in FIG. 8 are the same as those in the first embodiment, description thereof is omitted.

  Even when a plurality of condensing points of the Shack-Hartmann sensor have an overlap and a plurality of points intersect, it is possible to correctly associate the condensing points with the microlenses.

  FIG. 9 shows a flowchart. Measurement is started in step S101, a plurality of overlapping condensing points and microlenses are correctly associated by the procedure from step S102 to step S111, the center of gravity is calculated, and a plurality of intersections in the procedure from step S306 to step S307 are performed. The center of gravity can be calculated by correctly associating the light condensing point with the microlens. In addition, about FIG. 9, since it is the same as that of 1st Embodiment after step S112, description is abbreviate | omitted.

  As described above, according to the present embodiment, even when the CCD sensor region corresponding to the lens adjacent to the predetermined lens has a condensing point corresponding to the predetermined lens, the converging point and the micro lens are correctly associated with each other. Thus, it is possible to correctly measure the aberration of the light wavefront.

(Other embodiments)
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, etc.) of the system or apparatus reads the program. It is a process to be executed.

Claims (8)

An aberration measuring device that measures the aberration of the return light from the inspection object irradiated with the measurement light,
A dividing unit configured to have a plurality of divided areas that divide the return light into a plurality of lights, and the characteristics of at least one of the plurality of divided areas are different from the characteristics of the other divided areas; ,
Detecting means for detecting positions and shapes of a plurality of irradiation regions irradiated with each of the plurality of lights;
Determining means for determining a divided region corresponding to each of the plurality of irradiation regions based on the detected shape;
Obtaining means for acquiring inclinations of the plurality of lights for each of the plurality of divided regions based on the determined divided region and the detected position;
The aberration measurement apparatus, wherein the aberration is measured based on the acquired inclination.   2. The optical device according to claim 1, wherein the dividing unit is an optical unit configured so that optical characteristics of at least one of the plurality of divided areas are different from optical characteristics of the other divided areas. Aberration measuring device. Each of the plurality of divided regions has a plurality of optical members;
The aberration measuring apparatus according to claim 2, wherein the detection unit detects light collected by each of the plurality of lights.   The aberration measuring apparatus according to claim 3, wherein the optical unit is configured so that an optical characteristic of at least one optical member of the plurality of optical members is different from an optical characteristic of another optical member. .   The aberration measuring apparatus according to claim 3, wherein at least one of the plurality of optical members is a lens having a refractive power that is non-rotationally symmetric.   The aberration measuring apparatus according to claim 5, wherein the lens is a toric lens.   The aberration measuring apparatus according to claim 3, wherein at least one of the plurality of optical members is a lens having a refractive power that is a non-rotationally symmetric surface.   The aberration measuring apparatus according to claim 7, wherein the lens is a cylindrical lens.

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