JP5539174B2 - Wavefront measuring apparatus and wavefront measuring method - Google Patents

Description

  The present invention relates to a wavefront measuring apparatus and a wavefront measuring method, and more particularly to a wavefront measuring apparatus and a wavefront measuring method for measuring the wavefront of a light wave.

  For example, as a method of measuring the wavefront aberration of an astronomical telescope, focusing on an object at approximately infinity, and measuring the wavefront aberration of the astronomical telescope, the measurement light is transmitted from the image side of the astronomical telescope, and folded by a plane mirror installed on the object side of the astronomical telescope, Again, a double-pass wavefront measurement method is known in which the wavefront distortion of the measurement light returned to the image side of the astronomical telescope is measured with a wavefront measurement device.

  A conventional wavefront measuring apparatus used in the wavefront measurement includes a light source, an irradiation optical system including a matching lens, a test optical system, a folding mirror, a microlens array, and an image sensor. Yes (see, for example, Patent Document 1).

  In the wavefront measuring apparatus, after the light beam from the point light source is irradiated to the test optical system by the irradiation optical system, the optical path coming back from the return mirror is reversed, and the matching lens in the irradiation optical system from the test optical system , The substantially parallel light beam is guided to the microlens array, and the wavefront aberration of the optical system to be detected is calculated from the position of the light beam detected by the image sensor disposed on the focal plane of the microlens.

JP 2003-270091 A

  The conventional wavefront measuring apparatus described in Patent Document 1 is a wavefront measurement via an irradiation optical system and a test optical system, and an optical system misalignment as shown in FIG. 1B occurs. The problem is the wavefront aberration caused by the misalignment. Therefore, in this type of conventional wavefront measuring apparatus, it is important to correct the alignment of the optical system. However, as shown in FIG. 2, when measuring a wavefront having a diameter different from the opening of the wavefront measuring apparatus, the alignment deviation due to the positional deviation It is conceivable that the spot position focused on the detector coincides with the misalignment due to the tilt misalignment, and it is difficult to determine the cause of the misalignment. Therefore, even if there is a focused spot at the center position of the detector, there is a possibility that tilt deviation may occur, and there is a problem that it cannot be guaranteed that there is no alignment deviation.

  The present invention has been made to solve such a problem, and provides a wavefront measuring apparatus and a wavefront measuring method capable of accurately detecting an alignment deviation of an optical system and determining the cause of the alignment deviation. With the goal.

  The present invention is provided in an optical system for inputting a wavefront of a light wave, a lenslet array including a plurality of condenser lenses on which wavefronts from the optical system are incident, and a front stage or a rear stage of the lenslet array. Of all the condensing lenses of the lenslet array, light is transmitted through the entire surface corresponding to all the condensing lenses, or locally in order to enable only two or more specific condensing lenses. Mask means for switching whether to transmit light, a two-dimensional detector for converting a condensing spot generated by convergence of light transmitted through the condensing lens of the lenslet array into an image signal, and the two-dimensional detector An A / D converter that converts the output of the signal into a digital image signal, the output digital image signal of the A / D converter, and a reference spot position stored in advance, the wavefront calculation process is performed. Signal processing means, and at the time of alignment check, the mask means allows light to be transmitted locally to enable only a specific condenser lens among the condenser lenses of the lenslet array, and at the time of wavefront measurement. The wave front measuring apparatus is characterized in that light is transmitted through the entire surface in correspondence with all the condensing lenses of the condensing lenses of the lenslet array by the mask means.

  The present invention is provided in an optical system for inputting a wavefront of a light wave, a lenslet array including a plurality of condenser lenses on which wavefronts from the optical system are incident, and a front stage or a rear stage of the lenslet array. Of all the condensing lenses of the lenslet array, light is transmitted through the entire surface corresponding to all the condensing lenses, or locally in order to enable only two or more specific condensing lenses. Mask means for switching whether to transmit light, a two-dimensional detector for converting a condensing spot generated by convergence of light transmitted through the condensing lens of the lenslet array into an image signal, and the two-dimensional detector An A / D converter that converts the output of the signal into a digital image signal, the output digital image signal of the A / D converter, and a reference spot position stored in advance, the wavefront calculation process is performed. Signal processing means, and at the time of alignment check, the mask means allows light to be transmitted locally to enable only a specific condenser lens among the condenser lenses of the lenslet array, and at the time of wavefront measurement. The wave front measuring device is characterized in that light is transmitted through the entire surface in correspondence with all the condensing lenses of the condensing lens of the lenslet array by the mask means. It is possible to detect well and determine the cause of misalignment.

It is a figure explaining the alignment shift | offset | difference of the optical system in a wavefront measuring apparatus. It is a figure explaining the position shift and tilt shift in the case of measuring a wavefront having a diameter different from the opening of the wavefront measuring apparatus. It is a block diagram which shows the structure of the wavefront measuring apparatus which concerns on Embodiment 1 of this invention. It is a figure explaining the acquisition image (tilt and defocus) of the two-dimensional detector at the time of an alignment check. It is a block diagram which shows the structure of the wavefront measuring apparatus which concerns on Embodiment 2 of this invention. It is a block diagram which shows the structure of the wavefront measuring apparatus which concerns on Embodiment 3 of this invention.

  Hereinafter, preferred embodiments of a wavefront measuring apparatus and a wavefront measuring method of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding members and parts will be described with the same reference numerals.

Embodiment 1 FIG.
FIG. 3 is a configuration diagram showing the configuration of the wavefront measuring apparatus according to the first embodiment of the present invention. In FIG. 3, 1 is an incident wavefront, 2 is an optical system, 3 is a lenslet array, 4 is a mask provided with a pinhole, 5 is a mask moving mechanism, 6 is a two-dimensional detector, 7 is an A / D converter, Reference numeral 8 denotes a signal processing device 8. As shown in FIG. 3, the wavefront measuring apparatus according to the first embodiment is provided with a movably installed mask 4 at the subsequent stage of the optical system 2 on which the incident wavefront 1 is incident, and further at the subsequent stage. A lenslet array 3 is provided, and a two-dimensional detector 6 is provided at the subsequent stage. A signal processing device 8 is electrically connected to the two-dimensional detector 6 via an A / D converter 7. The mask 4 is provided with a mask moving mechanism 5 for inserting and retracting the mask 4 into and from the optical path. The mask moving mechanism 5 allows the mask 4 to move in a direction perpendicular to the optical path. The direction perpendicular to the optical path includes both (a) the horizontal direction (left-right direction) and (b) the up-down direction, as indicated by arrows in FIG.

Next, the operation of the wavefront measuring apparatus according to the first embodiment of the present invention will be described below with reference to FIG.
The incident wavefront 1 is a wavefront of a light wave incident on the optical system 2. The optical system 2 functions in the same manner as the matching lens in Patent Document 1, and the incident wavefront 1 incident on the optical system 2 is parallel light of a size that can enter the lenslet array 3 and the two-dimensional detector 6. And enters the lenslet array 3 (through the mask 4 if the mask 4 is inserted). The mask 4 is inserted into the optical path by the mask moving mechanism 5 during the alignment check, and is retracted from the optical path during the wavefront measurement. Although the installation location of the mask 4 is the front stage of the lenslet array 3 in FIG. 3, it is not limited to this, and may be the rear stage of the lenslet array 3. In addition, since the mask 4 is provided with several pinholes, when the mask is inserted, only a specific lenslet among the lenslets of the lenslet array 3 is activated. In the present embodiment, the mask 4 and the mask moving mechanism 5 transmit light entirely corresponding to all lenslets of the lenslets of the lenslet array 3 (when the mask is retracted), or In order to make only a specific lenslet effective, mask means for switching light locally (when a mask is inserted) is configured.

  The lenslet array 3 is composed of a plurality of condensing lenses (hereinafter referred to as lenslets) arranged in an array on a plane, and each lenslet has a local area of a wavefront (hereinafter referred to as a local wavefront). Is collected on the two-dimensional detector 6 placed at the focal position of the lenslet. The two-dimensional detector 6 is, for example, a CCD camera in which a large number of photoelectric converters are arranged in a lattice shape, and a large number of light collected on the two-dimensional detector 6 by convergence of each lenslet of the lenslet array 3. The image in which the light condensing spots are arranged is converted into an electric signal (image signal) and output to the A / D converter 7. The A / D converter 7 converts the electric signal (analog signal) representing the output image of the two-dimensional detector 6 into digitized digital image data and outputs the digital image data to the signal processing device 8. The signal processing device 8 includes image data storage means (not shown), reference spot position storage means (not shown), and arithmetic processing means (not shown) inside, and is A / D converted. The image data from the device 7 is stored in the image data storage means, and the arithmetic processing means is used to calculate the phase distribution of the measurement wavefront using the image data.

  Next, an operation at the time of alignment check, that is, a method for detecting misalignment will be described.

  In the wavefront measuring apparatus according to the first embodiment, a reference spot position (hereinafter referred to as a reference spot position) focused on the two-dimensional detector 6 when the mask 4 is inserted in order to perform an alignment check. .) Must be determined in advance and stored in the reference spot position storage means of the signal processing device 8. Therefore, first, in order to determine the reference spot position, the optical system 2 is placed at an optimal position so that no wavefront aberration occurs in the optical system 2, and the mask 4 provided with pinholes is inserted into the optical path. When the mask 4 is inserted into the optical path, only the local wavefront that has passed through the pinhole of the mask 4 is condensed on the two-dimensional detector 6 by the lenslet array 3. The two-dimensional detector 6 detects the position of the focused spot that has passed through the pinhole and outputs it to the signal processing device 8 via the A / D converter 7. In the signal processing device 8, the position of the focused spot is stored in the reference spot position storage unit as the reference spot position.

  At the time of wavefront measurement, the mask 4 is retracted by the mask moving mechanism 5 so as not to block the incident wavefront 1, and wavefront measurement is performed using the condensing spots of all lenslets of the lenslet array 3. Therefore, in this case, the incident wavefront 1 is incident on the lenslet array 3 from the optical system 2, and the light is converged by all the lenslets of the lenslet array 3 and condensed on the two-dimensional detector 6. The two-dimensional detector 6 detects the position of the focused spot and outputs it to the signal processing device 8 via the A / D converter 7. In the signal processing device 8, the digitized image data from the A / D converter 7 is stored in the image data storage means, and the arithmetic processing means is used to calculate the phase of the measurement wavefront using the image data. Find the distribution.

  In the alignment check, the mask 4 is inserted again by the mask moving mechanism 5 at the same position as when the reference spot is determined. The mask moving mechanism 5 is, for example, a stepping motor that can realize accurate positioning control, and can always place the mask 4 at the same position. Thus, the focused spot position of the local wavefront that has passed through the pinhole of the mask 4 is detected by the two-dimensional detector 6, and the detected focused spot position and the reference spot position previously stored in the signal processing device 8 are obtained. By comparing, the misalignment is detected. The signal processing device 8 includes a display device (not shown) for displaying the detection result on the screen to the user. As the detection result, the amount of movement and the movement between the detected focused spot position and the reference spot position are detected. The direction is displayed as a numerical value, an observation image as shown in FIG. 4 is displayed, or both the numerical value and the observation image are displayed. When the observation image is displayed on the screen, as shown in FIG. 4, the reference spot position is simultaneously displayed with a broken line or the like together with the detected focused spot.

  FIG. 4 is an example of an observation image in the two-dimensional detector 6 when the mask 4 provided with four pinholes on the top, bottom, left, and right with respect to the center point of the mask 4 is inserted during the alignment check. In FIG. 4A, all the focused spots are moved in the same direction (substantially) by the same distance with respect to the reference spot position (dotted circle), and a tilt shift can be detected. In this case, since all the focused spots move by the same distance in the same direction, the interval between the focused spots does not change. As described above, if the movement direction and the movement distance of the detected focused spot position from the reference spot position are detected from the comparison between the detected spot position and the reference spot position, whether or not the cause of the alignment deviation is the tilt deviation. Can be easily and accurately determined. Specifically, if all the detected focused spot positions have moved from the reference spot position by the same distance in the same direction, there is a tilt shift. Although the condensing spot position is deviated from the reference spot position without inserting the mask 4, the condensing spots of all the lenslets are observed, so that in which direction and how much tilt. (If the tilt amount is large, the focused spot closest to the reference spot position is not necessarily the focused spot originally located at the reference spot position). Therefore, since the number of condensing spots is smaller when the mask 4 is inserted, it is very easy to understand which direction and which distance are tilted.

  Next, in FIG.4 (b), the condensing spot is moving to the direction (radial direction) expanded from the center with respect to the reference | standard spot position (dotted circle). The amount of movement is (substantially) the same for all focused spots. Since the distance between the detected focused spot positions is changed by the movement, an alignment shift due to defocusing can be detected from the increase or decrease of the distance. As described above, if the moving direction and the moving distance of the detected focused spot position from the reference spot position are detected from the comparison between the detected spot position and the reference spot position, the cause of the alignment shift is a shift due to defocusing. It can be determined easily and accurately. Specifically, if all the detected focused spot positions move from the reference spot position in the radial direction by the same distance and the distance between the detected focused spot positions has changed, there is a deviation due to defocusing. is there. In this way, movement (shift) between the detected focused spot position and the reference spot position is detected, and the amount of movement of the detected focused spot position from the reference spot position and between the detected focused spot positions are detected. By increasing or decreasing the interval, it is possible to detect the presence or absence of misalignment, and to determine the cause of misalignment (whether tilt or defocus).

  In the wavefront measuring apparatus according to the first embodiment, the state of the incident wavefront 1 incident on the optical system 2 is not limited, and may be, for example, parallel light, convergent light, divergent light, or any wavefront shape. . Further, the optical system 2 is not limited to one lens, and for example, an afocal optical system using two convex lenses may be configured. In addition, the optical system 2 is not limited to a lens-only configuration, and may be configured using an optical component such as a beam splitter or a wavelength plate.

  Moreover, although the number of pinholes installed in the mask 4 is four, it is not limited to four. The number and arrangement position of the pinholes can be arbitrarily changed. Therefore, it is sufficient to determine the necessary quantity and arrangement position as appropriate and form the pinhole in the mask 4. However, when only one pinhole is installed, it is impossible to determine whether the cause of the alignment deviation is the influence of tilt or the influence of defocus, and therefore, at least two pinholes are required. As for the pinhole installation position, since the detection accuracy of misalignment due to defocusing is improved by widening the pinhole interval, it is desirable to keep the pinhole interval as far as possible in consideration of the size of the incident wavefront. Further, when pinholes are arranged on the same line, if any trouble occurs on the scanning line of the corresponding two-dimensional detector 6, it becomes impossible to accurately observe all the condensed spots, and alignment is performed. Since it is considered that adjustment cannot be performed, it is desirable to provide a pinhole other than on the same line.

  Further, the mask moving mechanism 5 is not limited to movement in only one axial direction. For example, the mask 4 is arranged at an arbitrary position with respect to the incident wavefront by using a moving mechanism operable in two axial directions. Therefore, even when a wavefront with a large tilt shift that falls outside the detection range of the two-dimensional detector 6 is incident at the fixed mask position, the wavefront measurement can be performed by expanding the detection range by moving the mask. Become.

  In the above-described alignment deviation detection method, when the reference spot position is determined in advance, an optimal arrangement that does not cause wavefront aberration in the optical system 2 is used as a reference. The light spot position may be used as the reference spot position. In this case, the aberration value can be corrected for the wavefront measured in the misalignment state by grasping in advance the aberration value at the time of misalignment and storing the aberration information in the signal processing device. Therefore, accurate wavefront measurement is possible even in the misalignment state.

  As described above, the wavefront measuring apparatus according to the first embodiment of the present invention inserts or retracts the mask 4 provided with several pinholes in front of or behind the lenslet array 3. A state in which the mask moving mechanism 5 is provided, the reference spot position observed when the mask 4 is inserted is stored in the signal processing device 8 in advance, and the mask 4 is inserted at the same position during the alignment check after wavefront measurement. If the condensing spot position is detected again and the condensing spot position is compared with the reference spot position, and these positions are misaligned, the optical system 2 is misaligned. Detecting movement (deviation) between the focused spot position and the reference spot position to increase the amount of movement of the detected focused spot from the reference spot position and the interval between the detected focused spot positions Accordingly, it is possible to detect the misalignment, it is also possible to determine the cause of the misalignment (tilt, another defocus).

Embodiment 2. FIG.
FIG. 5 is a configuration diagram showing the configuration of the wavefront measuring apparatus according to the second embodiment of the present invention.
The wavefront measuring apparatus according to the second embodiment of the present invention has an optical system alignment adjustment of the optical system 2 as shown in FIG. 5 in contrast to the configuration of the wavefront measuring apparatus according to the first embodiment shown in FIG. Since the mechanism 9 and the optical system control device 10 are added and the other points are the same, the same parts are denoted by the same reference numerals, and the description will be simplified. The optical system alignment adjusting mechanism 9 is provided for the optical system 2 and adjusts the direction of the optical system 2. Specifically, the optical system alignment adjustment mechanism 9 is a mechanism that can adjust the optical system 2 in the five-axis directions of the vertical direction, the horizontal direction, the focus direction, the rotation direction, and the tilt direction. An optical system controller 10 is electrically connected to the optical system alignment adjusting mechanism 9. The optical control device 10 receives the alignment deviation information from the signal processing device 8, outputs an optical system control signal based on the information, and inputs it to the optical system alignment adjustment mechanism 9. The optical system alignment adjustment mechanism 9 adjusts the lens position of the optical system 2 in accordance with the optical system control signal from the optical system control device 10 so that the reference spot position and the detected focused spot position coincide.

Next, the operation of the wavefront measuring apparatus according to the second embodiment of the present invention will be described.
In the first embodiment described above, only the function of detecting the misalignment of the optical system 2 from the misalignment of the focused spot observed by the two-dimensional detector 6 is provided. On the other hand, in the second embodiment, the misalignment information detected by the signal processing device 8 is input to the optical system control device 10. The optical control device 10 outputs an optical system control signal based on the misalignment information and inputs it to the optical system alignment adjustment mechanism 9 holding the optical system 2. The optical system alignment adjustment mechanism 9 is a mechanism that can adjust the optical system 2 in the five axis directions of the vertical direction, the horizontal direction, the focus direction, the rotation direction, and the tilt direction. In accordance with the control signal, the lens position is automatically adjusted with respect to at least one of the five axis directions so that the reference spot position and the focused spot coincide. Thereby, the misalignment is automatically corrected. Since other operations are the same as those in the first embodiment, description thereof is omitted here.

  As described above, in the present embodiment, the same effects as those of the first embodiment described above can be obtained. Further, in the present embodiment, alignment deviation information from the signal processing device 8 is input and alignment is performed. By including an optical system control device 10 that outputs an optical system control signal based on the deviation information and an optical system alignment adjustment mechanism 9 that adjusts the alignment of the optical system 2 based on the optical system control signal, automatic adjustment of alignment deviation is possible. Therefore, quick and accurate wavefront measurement can be performed.

  In the above description, the example in which the configuration of the present embodiment (the optical system alignment adjustment mechanism 9 and the optical system control device 10) is applied to the configuration of the first embodiment shown in FIG. 3 has been described. The configuration of the present embodiment is not limited to that case, and can be applied to a third embodiment to be described later. Also in that case, the same effect is produced.

Embodiment 3 FIG.
FIG. 6 is a configuration diagram showing the configuration of the wavefront measuring apparatus according to the third embodiment of the present invention.
The wavefront measuring apparatus according to the third embodiment of the present invention is not provided with the mask 4 provided with pinholes, instead of the wavefront measuring apparatus according to the first embodiment shown in FIG. Since the liquid crystal shutter 11 for the shutter is provided, the liquid crystal shutter control device 12 for controlling the liquid crystal shutter 11 is added, and the mask moving mechanism 5 is eliminated, the other parts are the same as in FIG. The same reference numerals are attached to the parts, and the description is simplified. The liquid crystal shutter 11 is composed of a plurality of light transmission type liquid crystal elements arranged in an array on a plane and subjected to an alignment process, and the transmission / blocking of light can be switched for each liquid crystal element. Therefore, the transmission or blocking of the local wavefront with respect to each lenslet of the lenslet array 3 can be freely controlled. The arrangement of the liquid crystal elements corresponds to the arrangement of the lenslets of the lenslet array 3 on a one-to-one basis. Therefore, the validity / invalidity of each lenslet is switched by transmitting / blocking light of each liquid crystal element. be able to. The liquid crystal shutter control device 12 controls the liquid crystal shutter 11 in accordance with an alignment check or a wavefront measurement by a user operation input or program control. That is, at the time of alignment check, for example, as shown in FIG. 6, light is transmitted through only four liquid crystal elements on the top, bottom, left, and right with reference to the center point of the liquid crystal shutter 11 (pinhole), and other liquid crystals The element is controlled to block light. At the time of wavefront measurement, all liquid crystal elements of the liquid crystal shutter 11 are controlled so as to transmit light and perform wavefront measurement. Therefore, the liquid crystal shutter 11 functions exactly the same as the mask 4 shown in the first embodiment of FIG. In FIG. 6, the installation location of the liquid crystal shutter 11 is the front stage of the lenslet array 3, but is not limited thereto, and may be the rear stage of the lenslet array 3. As described above, in the present embodiment, the liquid crystal shutter 11 and the liquid crystal shutter control device 12 transmit light entirely corresponding to all the lenslets of the lenslets of the lenslet array 3, or In order to make only a specific lenslet effective, mask means for switching whether to transmit light locally is configured.

Next, the operation of the wavefront measuring apparatus according to the third embodiment of the present invention will be described.
In the first embodiment described above, the alignment deviation of the optical system is detected from the positional deviation of the focused spot by inserting the mask 4 provided with pinholes. On the other hand, in the third embodiment, a liquid crystal shutter 11 is installed in front of or behind the lenslet array 3 instead of the mask 4, and the liquid crystal shutter control device 12 transmits light of each liquid crystal element of the liquid crystal shutter 11. Controls switching of / shutoff. Since the liquid crystal shutter 11 can freely control the transmission or blocking of the local wavefront corresponding to each lenslet of the lenslet array 3, the number and arrangement of pinholes transmitted through the local wavefront during alignment adjustment. The position can be determined freely. Further, since the wavefront measurement can be controlled so that the local wavefront of the entire surface of the liquid crystal shutter 11 is transmitted, a mechanism such as the mask moving mechanism 5 for moving the mask 4 as shown in FIG. 1 is unnecessary. However, when wavefront aberration occurs due to the transmission of the liquid crystal shutter 11, it is necessary to grasp the correction value in advance and correct it by the signal processing device 8. Therefore, a liquid crystal shutter moving mechanism (not shown) is provided. May be inserted and retracted. Since other operations are the same as those in the first embodiment, description thereof is omitted here.

  As described above, in the present embodiment, the same effects as those of the above-described first embodiment can be obtained, and in the present embodiment, the liquid crystal shutter 11 is provided in front of or behind the lenslet array 3. By controlling it with the liquid crystal shutter control device 12, the number and arrangement positions of the pinholes that transmit the local wavefront can be determined freely, so that it depends on the size of the incident wavefront and the tilt deviation. The pinhole can be set to the optimum condition for obtaining the alignment accuracy of the optical system 2. In addition, the local wavefront can be transmitted through the entire surface of the liquid crystal shutter 11, and the positional deviation of the pinhole position due to the insertion and withdrawal of the liquid crystal shutter 11 does not occur, thereby further improving the alignment adjustment accuracy and reproducibility.

  In the above description, the liquid crystal shutter and the liquid crystal shutter control device have been described as examples of the electronic shutter and the electronic shutter control device. However, the present invention is not limited to this, and a control signal from the electronic shutter control device If any one of the condenser lenses of the lenslet array can be switched to which one of the condenser lenses is to be activated and can transmit light corresponding to the condenser lens that is to be activated, Even an electronic shutter can be used. In this case, it goes without saying that the same effect can be obtained.

  DESCRIPTION OF SYMBOLS 1 Incident wavefront, 2 Optical system, 3 Lenslet array, 4 Mask, 5 Mask moving mechanism, 6 Two-dimensional detector, 7 A / D converter, 8 Signal processing apparatus, 9 Optical system alignment adjustment mechanism, 10 Optical system control Device 11 Liquid crystal shutter, 12 Liquid crystal shutter control device.

Claims (6)

An optical system for inputting the wavefront of the light wave;
A lenslet array comprising a plurality of condenser lenses on which the wavefront from the optical system is incident;
The lenslet array is provided before or after the lenslet array, and transmits light entirely corresponding to all of the condenser lenses of the lenslet array, or two or more specific condensers. Mask means for switching whether to transmit light locally to enable only the optical lens;
A two-dimensional detector for converting a focused spot generated by convergence of light transmitted through the condenser lens of the lenslet array into an image signal;
An A / D converter for converting the output of the two-dimensional detector into a digital image signal;
Signal processing means for performing calculation processing of the wavefront according to the output digital image signal of the A / D converter and a pre-stored reference spot position;
At the time of alignment check, the mask means transmits light locally in order to enable only a specific condenser lens among the condenser lenses of the lenslet array,
At the time of wavefront measurement, the mask means allows light to be transmitted through the entire surface in correspondence with all the condensing lenses of the condensing lenses of the lenslet array. The mask means includes
A mask provided with two or more pinholes for enabling only a specific condensing lens among the condensing lenses of the lenslet array, which is provided before or after the lenslet array;
2. The wavefront measuring apparatus according to claim 1, further comprising: a mask moving unit that inserts the mask into the optical path or retracts the mask from the optical path. The mask means includes
It is provided at the front stage or rear stage of the lenslet array, and the condenser lens of the lenslet array is switched to which one of the condenser lenses is to be activated, and the light corresponding to the condenser lens to be activated is selected. An electronic shutter that transmits light;
An electronic shutter control device that outputs a control signal and controls the switching of the electronic shutter.
The wavefront measuring apparatus according to claim 1, wherein the electronic shutter can arbitrarily change the number of light transmitting portions and the arrangement position.   The wavefront measuring apparatus according to claim 2, wherein the mask moving means is capable of moving and fixing the mask provided with the pinhole to an arbitrary position of the lenslet array. An optical system alignment adjusting means for adjusting the alignment deviation of the optical system by adjusting the orientation of the optical system;
An optical system control device for controlling the optical system alignment adjusting means based on an alignment correction signal from the signal processing means,
5. The wavefront measuring apparatus according to claim 1, wherein alignment adjustment of the optical system is performed based on an alignment correction signal from the signal processing means. Storing a reference spot position for use in alignment check;
Providing a mask means for switching light transmission / blocking at a front stage or a rear stage of a lenslet array composed of a plurality of condenser lenses;
The mask means is used to transmit light entirely to enable all of the condensing lenses of the lenslet array, or locally to enable only a specific condensing lens. A step of switching whether to transmit
Inputting the wavefront of the light wave into the optical system;
Injecting the wavefront from the optical system into a lenslet array;
Condensing the light transmitted through the condenser lens enabled by the mask means among the condenser lenses of the lenslet array;
Converting the focused spot generated by the focused light into an image signal;
Converting the image signal into a digital image signal;
Computing the wavefront from the digital image signal and the pre-stored reference spot position,
At the time of alignment check, in order to enable only a specific condensing lens among the condensing lenses of the lenslet array, the mask means transmits light locally,
A wavefront measurement method characterized by transmitting light over the entire surface in order to validate all the condensing lenses of the lenslet array during wavefront measurement.

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