JP2000329648A - Method and apparatus for evaluation of lens as well as adjusting apparatus for lens - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a new evaluation method, for a lens, as a substitute for a jitter method and a light intensity method by a method wherein light which is radiated from the lens is diffracted, beams of diffracted light at different orders are made to interfere, sharing interference light is obtained, the phase of the beams of diffracted light is changed and the phase of a change in light intensity is found in a plurality of measuring points on a sharing axis. SOLUTION: A laser beam 22 which is radiated from a laser generation source 21 is changed into parallel light 24 by a lens 23, and it is image-formed on a reflection-type diffraction grating 26 by an objective lens 25. A reflected laser beam 20 is reflected by a semitransparent mirror 27, and it is captured by an imaging element 28 so as to be processed by a signal processor 29. Then, in a region 34 in which zero-order diffracted light 31 and + first-order diffracted light 32 interfere, a change in terms of time in light intensity is measured in a point P1 and a point Pn which are at equal distance L from the center between the diffraction circle center O and the diffraction circle center O1 on a sharing axis which connects the diffraction circle center O of the zero-order diffracted light to the center O1 of the + first- order diffracted light. Then, the phase difference of a sine curve which expresses the change in the light intensity in the two points appears, and the characteristic (various aberrations) of the objective lens 25 is obtained on the basis of the phase difference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information storage medium of an optical disk system, for example, a DVD (Digital Vers).
and a device for detecting the characteristics of an optical lens that reads and writes information on an optical lens, forms an optical spot by forming light in a laser beam machine, a laser microscope, or the like, and a device therefor, and further adjusts the optical lens Apparatus and method.

[0002]

BACKGROUND OF THE INVENTION In order to read information from an optical disk type high-density information storage medium and to store the information in the high-density information storage medium, an optical system capable of accurately irradiating light emitted from a light source to a target location. A system is required. for that reason,
In particular, the objective lens of the optical system not only requires strict optical characteristics per se, but also must be accurately fixed to a target place.

As a method of inspecting or adjusting an objective lens, as shown in FIG. 1, light (eg, laser light) 2 emitted through an objective lens 1 is used as a reference 3 for lens inspection (eg, an optical disk). ), And this reference standard 3
And the reproduced signal 4 obtained from this detection is compared with the reference signal 5 so that the phase difference 6 between the reproduced signal 4 and the reference signal 5 is minimized or the phase difference is predetermined. It is conceivable to adjust the inclination and the like of the objective lens 1 so as to fall within the allowable value (jitter method).

However, in general, the characteristics of the objective lens 1 are different from each other, and there is no fixed relationship between the amount of tilt of the objective lens 1 and the like and the phase difference 6, and as shown in FIG. The other objective lens 1B may exhibit significantly different characteristics (lens tilt angle-phase difference characteristics). In addition, the tilt adjustment of the objective lens and the comparison of signals must be repeatedly performed, and it is difficult to objectively determine at which stage the adjustment is completed. Further, since the reproduction signal 4 includes characteristics peculiar to a circuit for obtaining the reproduction signal, the inclination of the objective lens 1 and the like cannot always be sufficiently grasped from the reproduction signal 4.

As an alternative to the jitter method, FIG.
As shown in FIG. 4, the light 12 transmitted through the objective lens 11 is condensed on an image pickup device (CCD) 14 via an enlargement optical system 13 including a lens, a mirror, and the like, and a beam spot captured by the image pickup device 14 (FIG. (A) and (B)) are displayed on the signal processing device 15 or the like, and the light intensity (shade pattern) of the beam spot displayed on the signal processing device 15 (see FIG. 4A) is observed. A method of inspecting or adjusting the inclination or the like of the lens 11 (light intensity measurement method) has been considered. In addition,
FIG. 4A shows a beam spot 16 displayed on the signal processing device 15 before adjustment and a shading pattern 17 formed around the beam spot 16.
FIG. 4B shows a beam spot 18 having no shading pattern, which is displayed on the signal processing device 15 after the adjustment.

However, in this light intensity measurement method, since the inclination or the like of the objective lens 11 is detected based only on the light intensity information, fine adjustment, for example, adjustment of the wavelength level of the light 12 cannot be performed. . Further, the sensitivity characteristics of the image sensor 14 differ depending on the location, and different detection results are generated depending on where the light 12 is received on the image sensor 14. Further, the defocus of the beam spot 18 significantly affects the detection result. Furthermore, since the magnifying optical system 13 is used, if the inclination angle of the objective lens 11 is adjusted,
In some cases, the beam spot 18 deviates from the above, and the result of the adjustment cannot be evaluated. Further, since the light intensity of the beam spot 16 is read visually by a person, individual differences are likely to occur in the inspection results and the like.

Accordingly, an object of the present invention is to provide a new lens evaluation method, a lens evaluation device, a lens adjustment device, and a lens adjustment method which are alternatives to the above-described jitter method and light intensity measurement method. .

[0008]

SUMMARY OF THE INVENTION The method for evaluating a lens of the present invention comprises the steps of (a)
Diffracting the light emitted from the lens, and obtaining a sharing interference image by causing two diffracted lights of different orders to interfere with each other;
(B) changing the phase of the diffracted light;
Obtaining a phase of a light intensity change at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image; Determining a characteristic of the lens.

According to another aspect of the present invention, there is provided an evaluation method comprising the steps of (a)
Diffracting the light emitted from the lens, and obtaining a sharing interference image by causing two diffracted lights of different orders to interfere with each other;
(B) changing the phase of the diffracted light;
Obtaining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through the midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image; X, where Y is the phase, the phase Y is approximated by a function of the measurement position X, and the characteristic of the lens is evaluated by the coefficient value of the function.

In these evaluation methods, a Schering interference image of the two diffracted lights may be transmitted through the lens.

According to another aspect of the present invention, there is provided an evaluation method comprising the steps of:
Light emitted from a light source is condensed by an objective lens, and the condensed light is projected on a reflection type diffraction grating, and two diffracted lights of different orders reflected from the reflection type diffraction grating are substantially parallelized by the objective lens. The light, which has been converted into the substantially parallel light, is condensed by a condensing lens, and the condensed light is focused on an image receiving surface to obtain a sharing interference image of the two diffracted lights on the image receiving surface. Process and
(B) moving the diffraction grating in a direction having a direction component orthogonal to the grating direction to change the phase of the diffracted light; and (c) in the shearing interference image, A step of obtaining the phase of the light intensity change at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes,
(D) obtaining a characteristic of the objective lens based on the phase.

According to another aspect of the present invention, there is provided an evaluation method comprising the steps of:
Light emitted from a light source is condensed by an objective lens, and the condensed light is projected on a reflection type diffraction grating, and two diffracted lights of different orders reflected from the reflection type diffraction grating are substantially parallelized by the objective lens. The light, which has been converted into the substantially parallel light, is condensed by a condensing lens, and the condensed light is focused on an image receiving surface to obtain a sharing interference image of the two diffracted lights on the image receiving surface. Process and
(B) moving the diffraction grating in a direction having a direction component orthogonal to the grating direction to change the phase of the diffracted light; and (c) in the shearing interference image, A step of obtaining the phase of the light intensity change at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes,
(D) When the measuring point position is X and the phase is Y,
Approximating the phase Y with a function of the measurement position X, and evaluating the optical characteristics of the objective lens with a coefficient value of the function.

According to another aspect of the present invention, there is provided an evaluation method comprising the steps of (a)
The light emitted from the light source is condensed by an objective lens, and the condensed light is projected on a transmission type diffraction grating, and two diffracted lights of different orders transmitted through the transmission type diffraction grating are converted into substantially parallel light by a lens. Converging the substantially parallel light with a condenser lens, forming the condensed light on an image receiving surface, and obtaining a sharing interference image of the two diffracted lights on the image receiving surface. (B) moving the diffraction grating in a direction having a direction component in a direction orthogonal to the grating direction to change the phase of the diffracted light; and (c) in the shearing interference image,
Obtaining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights; and (d) obtaining characteristics of the objective lens based on the phase. And a method for evaluating a lens.

According to another aspect of the present invention, there is provided an evaluation method comprising the steps of (a)
The light emitted from the light source is condensed by an objective lens, and the condensed light is projected on a transmission type diffraction grating, and two diffracted lights of different orders transmitted through the transmission type diffraction grating are converted into substantially parallel light by a lens. Converging the substantially parallel light with a condenser lens, forming an image of the condensed light on an image receiving surface, and causing the two diffracted lights to share and interfere on the image receiving surface; b) moving the diffraction grating in a direction having a direction component orthogonal to the grating direction to change the phase of the diffracted light;
(C) obtaining a phase of light intensity change at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image; When the point position is X and the phase is Y, the step of approximating the phase Y with a function of the measurement position X and evaluating the optical characteristics of the objective lens with the coefficient value of the function. And

In the above evaluation method, the two diffracted lights are desirably either one of the 0th-order diffracted light and the ± 1st-order diffracted light, or the + 1st-order diffracted light and the -1st-order diffracted light.

In the above evaluation method, the optical characteristics evaluated include the defocus amount, coma aberration, spherical aberration,
Astigmatism and aberrations other than these aberrations are included.

In the present invention, in particular, the method of evaluating the amount of defocusing is a method of evaluating the phase of the light intensity change at a plurality of measurement points on a line segment passing through the optical axis of the diffracted light in the sharing interference image. And when the measuring point position is X and the phase is Y, the phase Y is measured at the measuring position X
Is approximated by a linear function of or a function having a first or higher order,
A step of evaluating the defocus amount of the optical system using a first-order coefficient value of the approximation function.

A method for evaluating coma aberration is to measure a phase of a change in light intensity at a plurality of measuring points on a perpendicular bisector of a line connecting the optical axes of the diffracted light in the sharing interference image. And when the measuring point position is X and the phase is Y, the phase Y is approximated by a quadratic function of the measuring position X, and the coma aberration is evaluated by a quadratic coefficient value of the quadratic function. The step of performing

Another method for evaluating coma aberration is as follows:
In the sharing interference image, the measurement is performed by a plurality of measurements on two oblique lines passing through the midpoint of a line connecting the optical axes of the diffracted light and forming a predetermined angle in the positive and negative directions with respect to the line. Obtaining a phase of the light intensity change at the measurement point; (d)
For each of the two oblique lines, the measurement point position is X, the phase is Y, and the phase Y is approximated by a quadratic function or a cubic function of the measurement position X, and a quadratic function of the quadratic function or cubic function is obtained. A step of evaluating coma using the coefficient value.

Another method for evaluating coma aberration is as follows:
In the sharing interference image, a vertical bisector passing through the midpoint of the line segment connecting the optical axes of the diffracted light and two oblique lines forming a predetermined angle in the positive and negative directions with respect to the line segment Determining the phase of the light intensity change at the measurement point by a plurality of measurements; and (d) regarding the vertical bisector, the measurement point position is X, the phase is Y, and the phase Y is the measurement position X For the quadratic function or the cubic function obtained by approximating the quadratic function or the cubic function, and for the two oblique lines, the measuring point position is X, the phase is Y, and the phase Y is Evaluating the coma aberration using the difference between the quadratic function or the cubic function of the measurement position X and the second-order coefficient value of the quadratic function or the cubic function approximated.

The method for evaluating astigmatism includes the steps of (b) rotating the sharing direction of the sharing interference image, and (c) changing the phase of the diffracted light by moving the diffraction grating. (D) obtaining a phase of a change in light intensity at a plurality of measurement points on a perpendicular bisector of a line connecting the optical axes of the diffracted light in the sharing interference image; The measurement point position is X, the phase is Y, and the phase Y is approximated by a linear function of the measurement position X or a function having a first or higher order, and the first-order coefficient value of the approximate function is used for the optical system. And a step of evaluating astigmatism.

The step of rotating the sharing direction includes a step of rotating the diffraction grating by a predetermined angle. Alternatively, the step of rotating the sharing direction includes a step of rotating the lens by a predetermined angle. Alternatively, the step of rotating the sharing direction includes the step of diffracting light using the first diffraction grating having a grating groove formed in the first direction, and the step of diffracting light in a direction different from the first direction (for example, the first direction). Direction and 45 °
Diffracting light using a second diffraction grating having a grating groove formed in a direction at an angle of.

The method for evaluating the spherical aberration includes the step of (c) obtaining a phase of a change in light intensity at a plurality of measurement points on a line segment passing through the optical axis of the diffracted light in the sharing interference image. And (d) the measurement point position is X and the phase is Y, and the phase Y is approximated by a cubic function or a quartic function of the measurement position X, and the above is calculated using a cubic coefficient value of the cubic function or the quartic function. And evaluating a spherical aberration of the optical system.

The method for evaluating higher-order aberrations is as follows: (c) In the above-mentioned sharing interference image, the first measurement is performed at a plurality of first measurement points on a line segment connecting the optical axes of the two diffracted lights. Determining a first phase of the light intensity change at the point; a second phase at a plurality of second measurement points on a vertical bisector of the line segment;
A second phase of the light intensity change at the measurement point is determined. A plurality of third measurement points on a third oblique line passing through the midpoint of the line segment and forming a predetermined angle in the positive direction with respect to the line segment Calculating a third phase of the light intensity change at the third measurement point at a point; a plurality of fourth oblique lines passing through the midpoint of the line segment and forming a predetermined angle in the negative direction with respect to the line segment; Obtaining a fourth phase of the light intensity change at the fourth measurement point at the fourth measurement point;
(D) The first measurement point position is X and the first phase is Y
The first phase Y is approximated by a first function F of a first measurement position X, the second measurement point position is X, the second phase is Y, and the second phase Y Is approximated by the second function F of the second measurement position X, the third measurement point position is X, the third phase is Y, and the third phase Y is the third measurement position X. Approximate by a third function F, and the fourth measurement point position is X,
The fourth phase is defined as Y, the fourth phase Y is approximated by a fourth function F at a fourth measurement position X, and a residual Δ between the first function F and the first phase Y, The residual Δ between the second function F and the second phase Y, the residual Δ between the third function F and the third phase Y, and the residual Δ between the fourth function F and the fourth phase Y Residual Δ
Evaluating the higher-order aberration of the optical system based on the above.

The lens evaluation apparatus of the present invention implements the above-described evaluation method, and (a) diffracts the light transmitted through the condensing lens and shares the interference light of two diffracted lights of different orders. A diffraction grating for emitting light;
A moving mechanism for moving the diffraction grating, (c) an image receiving body for receiving the sharing interference light, and (d) an interference image of the sharing interference light received by the image receiving body.
A characteristic detector for determining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through the midpoint of a line segment connecting the optical axes of the two diffracted lights, and determining a characteristic of the condenser lens based on the phase. And

The diffraction grating may be either a reflection type diffraction grating or a transmission type diffraction grating.

According to another aspect of the present invention, there is provided an evaluation apparatus comprising:
(B) a light source for inputting substantially parallel light to the condenser lens;
While reflecting and diffracting the light transmitted through the condenser lens,
A reflection type diffraction grating that causes the sharing interference light of two diffracted lights of different orders to enter the condenser lens; (c) a moving mechanism for moving the diffraction grating; and (d) the transmission mechanism that has passed through the condenser lens. An imaging lens for imaging the sharing interference light; (e) an image receiving body for receiving the imaged sharing interference light; and (f) a sharing interference image received by the image receiving body. A characteristic detector for determining the phase of the light intensity change at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes of the diffracted light, and determining a characteristic of the condenser lens based on the phase. .

The evaluation device may include a mechanism for moving the image receiving body in the optical axis direction, a mechanism for moving the diffraction grating in the optical axis direction, and a mechanism for rotating the diffraction grating around the optical axis.

The lens adjusting method according to the present invention is embodied in a lens adjusting device. Specifically, the lens adjustment device according to the present invention includes: (a) a diffraction grating that diffracts the light transmitted through the condenser lens and emits a sharing interference light of two diffracted lights of different orders; b) a mechanism for moving the diffraction grating; (c) an image receiver for receiving the sharing interference light; and (d) an interference image of the sharing interference light received by the image receiver. A characteristic detector for determining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes, and determining a characteristic of the condenser lens based on the phase; An adjusting mechanism is provided for adjusting the position of the condenser lens based on the detection result of the characteristic detector.

A lens adjusting device according to another embodiment of the present invention includes:
(A) a diffraction grating that diffracts light transmitted through the condenser lens and emits a sharing interference light of two diffracted lights of different orders; (b) a mechanism for moving the diffraction grating; and (c). (D) in an interference image of the sharing interference light received by the image receiving body, on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights; A characteristic detector for obtaining a phase of a change in light intensity at a plurality of measurement points and obtaining characteristics of the condenser lens based on the phase; and (e) a second detector for receiving reflected light or transmitted light from the condenser lens. And (f) the second image receiving member.
And a lens adjustment mechanism for adjusting the position of the condenser lens based on information on light received by the image receiver.

In a lens adjusting device according to another aspect of the present invention, the condensing lens has an edge surface around the lens surface,
The second image receiver receives reflected light or transmitted light from the edge surface.

The diffraction grating may be either a reflection type diffraction grating or a transmission type diffraction grating.

The lens adjustment mechanism includes a mechanism for moving the condenser lens in the optical axis direction, a mechanism for moving the condenser lens in a direction perpendicular to the optical axis, and a mechanism for rotating the condenser lens about the optical axis. It is preferable to have

The lens adjusting device preferably has a mechanism for moving the image receiving body in the optical axis direction.

Further, the adjusting device preferably has a mechanism for moving the diffraction grating in the optical axis direction and a mechanism for rotating the diffraction grating around the optical axis.

A lens adjusting device according to another embodiment of the present invention includes:
(A) a light source; and (b) a lens that converts the light emitted from the light source into substantially parallel light and enters the condenser lens.
(C) a reflection type diffraction grating that reflects and diffracts the light condensed by the objective lens, and that causes the sharing interference light of two diffracted lights of different orders to enter the condensing lens;
(D) an imaging lens that forms an image of the sharing interference light emitted from the condenser lens; (e) an image receiver that receives the formed imaging light; and (f) an image receiver that receives the imaging light. In the received sharing interference image, the phase of the light intensity change is determined at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes of the two diffracted lights, and the light condensing is performed based on the phase. A characteristic detector for determining the characteristics of the lens.

A lens adjusting device according to another embodiment of the present invention includes:
(A) a light source; and (b) a lens that converts the light emitted from the light source into substantially parallel light and enters the condenser lens.
(C) a transmission diffraction grating that transmits and diffracts the light condensed by the condensing lens, and that inputs a sharing interference light of two diffracted lights of different orders into a second condensing lens;
(D) an imaging lens that forms an image of the sharing interference light emitted from the second condensing lens; and (e) an image receiving body that receives the formed sharing interference light.
(F) In the sharing interference image received by the image receiving body, a phase of a light intensity change is obtained at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights. And a characteristic detector for obtaining the characteristics of the condenser lens based on the above.

In the evaluation device and the detection device described above, the characteristic detector for evaluating the defocus amount is a device that measures the light intensity at a plurality of measurement points on the line connecting the optical axes of the diffracted light in the sharing interference image. The phase of the change is obtained, the measurement point position is X, the phase is Y, and the phase Y is approximated by a linear function of the measurement position X, and the data of the optical system is calculated by a linear coefficient value of the linear function. Evaluate the amount of focus.

The characteristic detector for evaluating the coma component passes through the center point of a line segment connecting the optical axes of the diffracted light in the shearing interference image and has a predetermined direction in the positive and negative directions with respect to the line segment. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on two oblique lines forming an angle (about 30 to 60 °). For each of the two oblique lines, the measurement point position is X, and the phase is Y. Then, the phase Y is approximated by a quadratic function or a cubic function of the measurement position X, and the coma is evaluated using the quadratic coefficient value of the quadratic function or the cubic function.

The characteristic detector that evaluates another coma component uses a vertical bisector passing through the midpoint of the line connecting the optical axes of the diffracted light and a positive bisector in the sharing interference image. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on two oblique lines forming a predetermined angle (about 30 to 60 °) with the direction and the negative direction, and the measurement point position is determined for the vertical bisector. X, the phase is Y, and the quadratic or cubic function of the quadratic or cubic function obtained by approximating the phase Y with a quadratic or cubic function of the measurement position X, and the two oblique lines, The difference between the measurement point position X and the phase Y, and the quadratic or cubic function of the quadratic function or cubic function obtained by approximating the phase Y with the quadratic function or cubic function of the measurement position X. Is used to evaluate coma.

The characteristic detector for evaluating astigmatism uses a plurality of measuring points on a vertical bisector of a line connecting the optical axes of the diffracted lights in the sharing interference image to measure the light intensity change at the measuring points. The phase is obtained, the measuring point position is X, the phase is Y, and the phase Y is approximated by a linear function of the measuring position X.
The astigmatism of the optical system is evaluated by the first order coefficient value of the next function.

The characteristic detector for evaluating the spherical aberration obtains the phase of the light intensity change at a plurality of measurement points on the line segment passing through the optical axis of the diffracted light in the sharing interference image, The measuring point position is X, the phase is Y, the phase Y is approximated by a cubic function or a quartic function of the measuring position X, and the spherical aberration of the optical system is calculated by a cubic coefficient value of the cubic function or quaternary function. evaluate.

The characteristic detector for evaluating higher-order aberrations includes: in the above-mentioned shearing interference image: a plurality of first measuring points on a line segment connecting the optical axes of the two diffracted lights; Calculating the first phase of the light intensity change at the second; and calculating the second phase at a plurality of second measurement points on a vertical bisector of the line segment.
A second phase of the light intensity change at the measurement point is determined. A plurality of third measurement points on a third oblique line passing through the midpoint of the line segment and forming a predetermined angle in the positive direction with respect to the line segment Calculating a third phase of the light intensity change at the third measurement point at a point; a plurality of fourth oblique lines passing through the midpoint of the line segment and forming a predetermined angle in the negative direction with respect to the line segment; The fourth phase of the light intensity change at the fourth measurement point is obtained at the fourth measurement point.
, The first phase Y is approximated by a first function F of the first measurement position X, and the second measurement point position is X, The second phase is Y, the second phase Y is approximated by a second function F of a second measurement position X, the third measurement point position is X, and the third phase is Y, The third phase Y is approximated by a third function F of a third measurement position X, the fourth measurement point position is X, the fourth phase is Y, and the fourth phase Y is 4th measurement position X
, The residual Δ between the first function F and the first phase Y, the residual Δ between the second function F and the second phase Y, the third function F The higher order aberration of the optical system is evaluated based on the residual Δ with the third phase Y and the residual Δ with the fourth function F and the fourth phase Y.

The diffraction grating has the following characteristics: 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (8 / λ) ≦ 2 0.2 ≦ du ≦ 0. 8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: incident light of light incident on the diffraction grating from the condenser lens Angle) nk: Refractive index of diffraction grating λ: Designed to satisfy the condition of light wavelength.

The conditions of the diffraction grating are as follows: 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (4 / λ) ≦ 2 0.2 ≦ du ≦ 0 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (4 / λ) ≦ 1.2 4 ≦ du ≦ 0.6, 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (2 / λ) ≦ 1.2 0.4 ≦ du ≦ 0.6.

[0046]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described.

(1) First Embodiment FIG. 5 shows a schematic configuration of a lens evaluation device 20. In the system 20, a laser source 21, which is a light source, emits coherent laser light (for example, helium neon laser light) 22. The emitted laser light 22 is adjusted to substantially parallel light 24 by a lens 23, and then is imaged on a reflective diffraction grating 26 by an objective lens 25. The laser light 20 reflected by the diffraction grating 26 returns to the substantially parallel light 24 through the objective lens 25 again, is reflected by the half mirror 27 disposed between the objective lens 25 and the lens 23, and (For example, a CCD sensor) 28. The image pickup device 28 is connected to a signal processing device 29, and an image captured by the image pickup device 28 is subjected to signal processing by the signal processing device 29, and a processing result is displayed on a display device 30.

In this system 20, as shown in FIG. 6, the 0th-order diffracted light 31, ± 1st-order diffracted light 3
.. Are obtained. The diffracted light 31 and the like form the interference image shown in FIG. 7 on the image sensor 28 by appropriately designing the groove interval (grating pitch) and the groove depth (grating depth) of the diffraction grating 26. Can be. Suitable design conditions will be described later.

Now, the interference image is a zero-order diffracted light (diffraction image) 3
1, the ± 1st-order diffracted lights (diffraction circles) 32 and 33 are shown without overlapping and in contact with each other. Hereinafter, "sharing" or "sharing interference" refers to such interference of diffracted lights of different orders, "sharing interference image" refers to an image formed by the interference, and an axis connecting the centers of the diffracted lights (an X-axis shown in FIG. 7). ) Is called the "sharing axis" and the direction of the sharing axis is called the "sharing direction."

When the objective lens 25 contains no aberration and the objective lens 25 is accurately focused on the diffraction grating 26, for example, the interference region 34 between the 0th-order diffracted light 31 and the + 1st-order diffracted light 32 becomes An interference area 35 of the zero-order diffracted light 31 and the -1st-order diffracted light 33 which is expressed in a plain black color.
Is represented in white without any shadow. However, an actual lens includes various aberrations, and interference fringes corresponding to these aberrations appear in the interference regions 34 and 35.

Regarding the light intensities at two points apart in the interference regions 34 and 35, the light intensities at these two points show different values depending on the aberration of the objective lens 25 and the like. When the diffraction grating 26 is moved in a direction perpendicular to the grating grooves (the left-right direction in FIG. 5) by using a suitable moving mechanism (indicated by reference numeral 36 in FIG. 5) using a piezo element, for example, 3
The light intensity at the two points 4 and 35 changes periodically while drawing a sinusoidal curve. At the same time, the difference in aberration appears as a phase difference between the two sinusoidal curves.

For example, as shown in FIG.
Looking at the interference region 34 between the 1st and + 1st order diffracted lights 32, the center O of the diffraction circle of the 0th order diffracted light 31 and the + 1st order diffracted light 32
On a sharing axis (X-axis) connecting the diffraction circle center O ₁ with the center O and O ₁ at the same distance L from the center.
When the temporal change of the light intensity is measured at points P ₁ and P _n , as shown in FIG. 9, a sine curve T ₁ representing the light intensity change at point P ₁ is obtained.
Between the phase φ (P ₁ ) and the phase φ (P _n ) of the sinusoidal curve T _n representing the light intensity change at the point P _n , and the phase difference Δφ is the aberration of the objective lens 25. And so on.

By the way, the aberration that occurs when the incident light is monochromatic is called monochromatic aberration.
There are coma, astigmatism, field curvature, and distortion (Seidel's five aberrations). Monochromatic aberrations can also be classified into ray aberrations and wavefront aberrations depending on the difference in the description of the aberrations. It is known that the ray aberration and the wavefront aberration can be converted into each other, and the liquid aberration is usually expressed using polar coordinates.

Hereinafter, for simplicity of description, in this application, the wavefront aberration is divided into coma, astigmatism, spherical aberration, other higher-order aberrations, and defocus.

As shown in FIG. 10A, the defocused wavefront 37 has a rotationally symmetrical shape around the optical axis with respect to a plane wave, and can be expressed by the following equation (1). Equation 1 φ = m · (ξ ² + η ² ) (1) m: constant Therefore, when two diffracted lights interfere in the ξ direction, and when two diffracted lights interfere in the η direction, The intensity difference (ie, phase difference) between the two interference lights is expressed as a linear function of Expressions (2) and (3) in the sharing direction. Equation 2 dφ / dξ = 2mξ (2) Equation 3 dφ / dη = 2mη (3)

This can also be understood from the fact that when there is no other aberration or the like in the lens, the defocus appears as an interference fringe 38 shown in FIG. 11A on the sharing interference image. Therefore, as shown in FIG. 12A, a sharing axis (X axis) connecting the center O of the diffraction circle of the 0th-order diffracted light 31 and the center O1 of the diffraction circle of the + _1st-order diffracted light 32 on the sharing interference image 39. Above, preferably a plurality of points (P ₁ , P ₂ ,..., Symmetrically about a bisector (Y axis) passing through the centers O, O ₁ and orthogonal to the sharing axis (X axis).
P _n−1 , P _n ), the diffraction grating 26 is moved in a direction perpendicular to the grating grooves, and the points (P ₁ , P ₂ ,..., P _n−1,.
Obtains a phase change of P _n), as shown in FIG. 12 (B), these points _{(P 1, P 2, ...} , P n-1, X coordinates and each point phase _{P n)} φ P (Φ _P1 , φ _P2 , ..., φ _{P (n-1)} , φ _Pn )
Is plotted on the coordinates, and the plotted points are approximated (fitted) with a linear function, whereby the defocus amount (constant m in equations (1) to (3)) can be quantitatively obtained.

The specific procedure for evaluating the amount of defocus using the signal processing device 24 is as follows. (i) As shown in FIG. 12A, the center of the diffracted lights (diffraction circles) 31 and 32 (optical axis) is received on the image sensor 28 and displayed on the sharing interference image 39 displayed on the display device 30. O, O ₁ ) and the sharing axis (X axis). (ii) On the sharing axis (X axis), a plurality of measurement points (P ₁ ,
P ₂ ,..., P _n−1 , P _n ). These measurement points are preferably arranged symmetrically with respect to the bisector (Y axis) of the line connecting the optical axes O and O ₁ . (iii) The moving mechanism 36 is driven to move the diffraction grating 26 in a direction orthogonal to the grating. (iv) Measurement points (P ₁ ,
P ₂ ,..., P _n−1 , P _n ) are measured. Note that the light intensity is obtained from the output signal of the image sensor at the position corresponding to the measurement point. The measured light intensity changes sinusoidally for each measurement point. (v) The phase φ _P (φ _P1 , φ
_P2 , ..., φP _(n-1) , _φPn ). The light intensity sine waveform corresponding to each measurement point has a different phase, for example, as shown in FIG. (vi) The light intensity φ _P (φ _P1 , φ _P
P2 ,..., ΦP _(n-1) , _φPn ) are plotted in a rectangular coordinate system as shown in FIG. (vii) A linear function (φ = mx) is fitted to the plotted points. (viii) The primary coefficient (m) of the fitted linear function is obtained, and the defocus amount is evaluated.

The coma aberration can be expressed by equation (4) with the wavefront 40 shown in FIG. Equation 4 φ = m · η · (ξ ² + η ² ) (4) m: Constant As shown in Expression (4), coma aberration has directionality in a direction with a large order (η direction: coma direction). . This top direction does not coincide with the sharing direction, and it is necessary to separately obtain the top component in the sharing direction and the top component in the direction orthogonal thereto, and to obtain the top direction from the ratio of their sizes. .

The top component in the sharing direction (ie,
A coma component in a direction orthogonal to the lattice groove is hereinafter referred to as a "coma R component". ) Is represented by equation (5). Equation 5 dφ / dη = m _R · (ξ ² + 3η ² ) (5) When it is assumed that there is no other aberration in the lens, the coma R component is the interference shown in FIG. Appears as stripes 41. Therefore, as shown in FIG. 13A, on the sharing interference image 42, on the Y axis,
Preferably, a plurality of points (P ₁ , P ₂ ,
.., P _n−1 , P _n ) and moving the diffraction grating 26 in a direction perpendicular to the grating direction, each point (P ₁ , P ₂ ,.
_n−1 , P _n ) phase φ _P (φ _P1 , φ _P2 ,..., φ _{P (n-1)} , φ
_Pn ), and as shown in FIG. 13B, the coordinates (Y coordinate) of these points and the phases φ _P (φ _P1 , φ _P2 ,.
_{P (n-1)} , φ _Pn ) are plotted on the coordinates, and the plotted points are fitted with a quadratic function to obtain a frame R based on the quadratic coefficient (m _R ) of the quadratic function. The component (constant m _{R in} equation (4)) can be quantitatively determined.

On the other hand, a coma component in a direction orthogonal to the sharing direction (that is, a coma component in a direction parallel to the lattice groove, hereinafter referred to as a "coma T component") is represented by Expression (6). Equation 6 dφ / dξ = m _T · (2ξη) (6) If there is no other aberration in the lens, it appears as an interference fringe 41 shown in FIG. 11C in the sharing interference image. Therefore, as shown in FIG. 14A, on the sharing interference image 44, it is preferable that the X-axis and the Y-axis form a predetermined angle (for example, 45 degrees) in the positive and negative directions with respect to the Z and Z 'axes. Represent a plurality of points (Q) symmetrically with respect to the intersection of the X axis and the Y axis.
_{1, Q 2, ..., Q} n-1, Q n), (R 1, R 2, ..., R n-1,
R _n ), and while moving the diffraction grating 26 in a direction orthogonal to the grating, each point (Q ₁ , Q ₂ ,..., Q _n-1 , Q _n ), (R
₁ , R ₂ ,..., R _n−1 , R _n )
As shown in (B) and (C), the coordinates Z,
Z ′ and the phase φ _{Q of} each point (φ _Q1 , φ _Q2 , ..., φ _{Q (n-1)} , φ
_{Qn), φ R (φ R1} , φ R2, ..., φ Rn-1, φ Rn) was plotted on the coordinate, also two plotted points each linear function ^{_{(φ = m T · x 2}} , φ '= m _T ′ · x ² ) or a cubic function and further calculating the difference between the quadratic coefficients (m _T , m _T ′) of these quadratic functions or cubic functions to quantitatively determine the coma T component be able to. From the ratio between the coefficient m _R of the frame _R component and the difference (m _T −m _T ′) of the frame T component,
The direction of coma can be determined.

A specific procedure for evaluating the coma R component is as follows. (i) As shown in FIG.
2, on the center of the diffracted light (diffraction circle) 31, 32 (optical axis O,
O ₁ ), a sharing axis (X axis), and a perpendicular bisector (Y axis) of a line connecting the optical axes O and O ₁ are determined. (ii) Multiple measurement points (P ₁ ,
P ₂ ,..., P _n−1 , P _n ). These stations are X
Preferably, they are arranged symmetrically with respect to the axis. (iii) The diffraction grating 26 is moved in a direction orthogonal to the grating. (iv) Measure the light intensity at the measurement points (P ₁ , P ₂ ,..., P _n−1 , P _n ). (v) The phase φ _P (φ _P1 , φ
_P2 , ..., φP _(n-1) , _φPn ). (vi) The phase φ _{P of} light intensity corresponding to the Y-axis coordinate of each measurement point (φ
_P1 , _φP2 ,..., ΦP _(n-1) , _φPn ) are plotted in a rectangular coordinate system as shown in FIG. (vii) A quadratic function (φ = m _R · x ² ) is fitted to the plotted points. (viii) The quadratic coefficient of the fitted quadratic function (m _R )
And evaluate the top R component.

A specific procedure for evaluating the coma T component is as follows.
It is on the street. (i) As shown in FIG.
4, on the center of the diffracted light (diffraction circle) 31, 32 (optical axis O,
O₁), Sharing axis (X axis), and optical axes O, O₁Tie
The perpendicular bisector (Y axis) of the line segment, the intersection of the X axis and the Y axis
And positive (counterclockwise) and negative with respect to the X axis
Direction (clockwise) at a predetermined angle θ (30 ° ≦ θ ≦ 60
(Preferably 45 °) Z axis and Z ′ axis are determined. (Ii) A plurality of measurement points (Q₁,
Q_Two, ..., Q_n-1, Q_n), (R₁, R_Two, ..., R_n-1,
R_n). These stations are located at the intersection of the X and Y axes.
Preferably, they are arranged symmetrically. (iii) The diffraction grating 26 is moved in a direction orthogonal to the grating. (iv) Measurement points (Q₁, Q_Two, ..., Q_n-1, Q_n), (R₁, R_Two,
…, R_n-1, R_n) Is measured. (v) Phase φ of light intensity sine waveform for each measurement point_Q(Φ_Q1, Φ
_Q2,…, Φ_{Q (n-1)}, Φ_Qn), Φ_R(Φ_R1, Φ_R2,…, Φ
_Rn-1, Φ_Rn). (vi) Light intensity corresponding to the Z-axis coordinate and Z'-axis coordinate of each measurement point
Phase φ_Q(Φ_Q1, Φ_Q2,…, Φ_{Q (n-1)}, Φ_Qn), Φ
_R(Φ_R1, Φ_R2,…, Φ_Rn-1, Φ_Rn) And FIG.
As shown in (B) and (C), plotting is performed in a rectangular coordinate system.
You. (vii) Quadratic function φ = m_T・ X^{Two ,}φ '= m
_T’· X^TwoFitting. (viii) The quadratic coefficient m of the fitted quadratic function_T,
m_T’. (ix) Difference m of quadratic coefficient_T-M_T’And evaluate the top T component
I do. (x) Top R component (m_R) And the difference (m_T−
m_T’))_R/ (M_T-M _T′) To the direction of coma
To evaluate.

The astigmatism takes the shape of the wavefront 45 shown in FIG. 10C with reference to the plane wave. In this astigmatism, the phase is quadratically distributed in a certain direction and a direction orthogonal thereto. In addition, the signs of the quadratic functions are opposite to each other, that is, axes having a downwardly convex distribution (ξ in FIG. 10C).
Axis) and an axis (η axis in FIG. 10C) showing an upwardly convex distribution. The interference fringes formed by overlapping the wavefronts 42 are
In the case of sharing in the ξ and η directions, each linear function appears as a stripe perpendicular to the sharing axis.
(See FIG. 11D.) However, when sharing is performed in a direction different from the ξ and η directions, a phase distribution occurs as a linear function with respect to an axis perpendicular to the sharing axis, and interference fringes parallel to the sharing axis are generated. . When sharing in a direction that forms an angle of 45 degrees with the ξ and η directions, the phase distribution appears only on an axis orthogonal to the sharing axis, and the interference fringes become parallel to the sharing axis (see FIG. 11D). Interference fringes at 46). Therefore, by extracting the linear function component of the phase distribution on a straight line orthogonal to the sharing axis, astigmatism in a specific direction can be quantitatively obtained.

More specifically, as shown in FIG. 15A, on the sharing interference image 47, a plurality of points (P ₁ , P ₂ ,..., P _n-1 , _Pn )
, And while moving the diffraction grating 26 in a direction orthogonal to the grating direction, the phase φ _P (φ _P1 , φ _P2,.
Changes in _{φP (n-1)} and _φPn ) are obtained, and as shown in FIG. 15B, the coordinates (Y coordinate) of these points and the phase φ of each point are obtained.
_P (φ _P1 , φ _P2 ,..., Φ _{P (n-1)} , φ _{P n} ) is plotted on the coordinates, and the plotted points are approximated by a linear function to quantitatively determine astigmatism. You can ask.

When the astigmatism component in a specific direction is detected, it is not necessary to change the sharing direction. However, when detecting the direction and magnitude of astigmatism, it is necessary to execute the above-described detection procedure for a specific direction and another direction that forms an angle of a predetermined angle (45 °) with the specific direction. In this case, the method of changing the sharing direction is to rotate the diffraction grating, rotate the lens, or, as shown in FIG.
A method is conceivable in which a first diffraction grating 301 formed with a pattern and a second diffraction grating 303 formed with a grating groove 302 in a direction forming a predetermined angle (45 °) with the specific direction are conceivable.

The specific procedure for evaluating astigmatism is as follows. (i) As shown in FIG.
7, the center of the diffracted light (diffraction circle) 31, 32 (optical axis O,
O ₁ ) (not shown), a sharing axis (X axis), and a perpendicular bisector (Y axis) of a line connecting the optical axes O and O ₁ are determined. (ii) A plurality of measurement points (P ₁ , P ₂ ,..., P _n−1 ,
P _n ). These measurement points are preferably arranged symmetrically with respect to the X axis. (iii) The diffraction grating 26 is moved in a direction orthogonal to the grating. (iv) Measure the light intensity at the measurement points (P ₁ , P ₂ ,..., P _n−1 , P _n ). (v) The phase φ _P (φ _P1 , φ
_P2 , ..., φP _(n-1) , _φPn ). (vi) The phase φ _{P of the} light intensity corresponding to the X-axis coordinate of each measurement point (φ
_P1 , _φP2 ,..., ΦP _(n-1) , _φPn ) are plotted in a rectangular coordinate system as shown in FIG. (vii) A linear function (φ = mx) is fitted to the plotted points. (viii) A first order coefficient (m) of the fitted linear function is obtained, and astigmatism is evaluated.

As shown in FIG. 10D, when a plane wave is used as a reference, the wavefront 44 of the spherical aberration has a rotationally symmetrical shape around the optical axis and can be expressed by the following equation (7). Equation 7 φ = d · (ξ ² + η ² ) ² (7) d: constant Therefore, when sharing in the ξ direction and when sharing in the η direction, 2
The intensity difference (that is, phase difference) between the two interference lights is expressed as a cubic function of Expressions (8) and (9) in the sharing direction. Equation 8 dφ / dξ = 2d (ξ ² + η ² ) (2ξ) (8) Equation 9 dφ / dη = 2d (ξ ² + η ² ) (2η) (9)

This means that assuming that there is no other aberration or the like in the lens, the spherical aberration is shown in FIG.
This can also be understood from the fact that the interference fringes 49 appear as shown in FIG. Therefore, as shown in FIG. 16A, on the sharing interference image 50, on the X axis, preferably, the center O,
A plurality of points (P ₁ , P ₂ , P ₁ , P ₂ ) symmetrically with respect to a bisector (Y axis) passing through the center of O ₁ and orthogonal to the sharing axis (X axis).
P ₂ ,..., P _n−1 , P _n ), the diffraction grating 26 is moved in a direction perpendicular to the grating grooves, and each point (P ₁ , P ₂ ,.
The phase change of P _n−1 , P _n ) is obtained, and the X of these points (P ₁ , P ₂ ,..., P _n−1 , P _n ) is obtained as shown in FIG.
Coordinate and phase of each point φ _P (φ _P1 , φ _P2 , ..., φ _{P (n-1)} , φ
_Pn ) is plotted on the coordinates, and the plotted points are approximated (fitted) by a cubic function, whereby the spherical aberration (constant d in equations (6) to (8)) can be quantitatively determined.

The specific procedure for evaluating the spherical aberration is as follows. (i) As shown in FIG. 16A, the center (optical axis O, O ₁ ) and the sharing axis (X axis) of the diffracted lights (diffraction circles) 31, 32 are determined on the interference image 50. (ii) A plurality of measurement points (P ₁ , P ₂ ,..., P _n−1 ,
P _n ). These measurement points are preferably arranged symmetrically with respect to the bisector (Y axis) of the line connecting the optical axes O and O ₁ (not shown). (iii) The diffraction grating 26 is moved in a direction orthogonal to the grating. (iv) Measure the light intensity at the measurement points (P ₁ , P ₂ ,..., P _n−1 , P _n ). (v) The phase φ _P (φ _P1 , φ
_P2 , ..., φP _(n-1) , _φPn ). (vi) The phase φ _{P of the} light intensity corresponding to the X-axis coordinate of each measurement point (φ
_P1 , _φP2 ,..., ΦP _(n-1) , _φPn ) are plotted in a rectangular coordinate system as shown in FIG. (vii) A cubic function (φ = mx ³ ) or a quartic function is fitted to the plotted points. (viii) The third order coefficient (m) of the fitted function is obtained, and the spherical aberration is evaluated.

High-Order Aberrations High-order aberrations include aberration components other than the above-described defocus, coma, astigmatism, and spherical aberration. Therefore, when evaluating the defocus, coma, astigmatism, and spherical aberration, the residual between the fitted function (linear function, quadratic function, and cubic function) and the phase are obtained, so that it can be quantitatively grasped. it can.

More specifically, as shown in FIG. 17A, on the sharing interference image 51, the X-axis, the Y-axis, and the Z-axis and the Z-axis that form a predetermined angle in the positive and negative directions with the X-axis. A plurality of points (P ₁ , P ₂ ,..., P _n−1 , P _n ), (Q ₁ , Q ₂ ,.
_{Q n-1, Q n)} (R 1, R 2, ..., R n-1, R n), (S 1,
S ₂ ,..., S _n−1 , S _n ), the phase change and the phase difference at each point are obtained while moving the diffraction grating 26 in a direction orthogonal to the grating direction, and FIG. ), (D),
As shown in (E), the coordinates of these points and the phase difference of each point are plotted on the coordinates, and the plotted points P, R, S
Are each fitted with a quadratic function, and the point Q
Is fitted with a cubic function, and the residual between the quadratic function and the cubic function and the plotted phase value is determined, whereby high-order aberrations can be quantitatively evaluated.

The specific procedure for evaluating higher-order aberrations is as follows.
It is. (i) As shown in FIG.
1, the optical axes O, O₁Sharing axis (X axis) connecting
Optical axis O, O₁Bisecting line (Y axis), X axis
Through the point of intersection of the
A predetermined angle θ in the clockwise direction) and the negative direction (clockwise).
(30 ° ≦ θ ≦ 60 °, preferably 45 °)
Axis and Z ′ axis are determined. (Ii) A plurality of measurement points P (P₁,
P_Two, ..., P_n-1, P_n), Q (Q₁, Q_Two, ..., Q_n-1, Q
_n), R (R₁, R_Two, ..., R_n-1, R_n), S (S₁,
S_Two, ..., S_n-1, S_n). These stations are X
It is preferable to arrange them symmetrically with respect to the intersection of the axis and the Y axis. (iii) The diffraction grating 26 is moved in a direction orthogonal to the grating. (iv) Measure the light intensity at the measuring points P, Q, R, and S. (v) Obtain the phase of the light intensity sine waveform for each measurement point. (vi) Phase φ of light intensity at each measurement point_P(Φ_P1, Φ_P2,…, Φ
_{P (n-1)}, Φ_Pn), Φ_Q(Φ_Q1, Φ_Q2,…, Φ_{Q (n-1)}, Φ
_Qn), Φ_R(Φ_R1, Φ_R2,…, Φ_Rn-1, Φ_Rn), Φ_S(Φ
_S1, Φ_S2,…, Φ_{S (n-1)}, Φ_Sn) To FIG. 17 (B),
As shown in (C), (D) and (E),
Lot. (vii) The plotted points (φ_P, Φ_Q, Φ_R) Is a quadratic function φ_P
= Mx^Two _,φ_Q= M_T・ X^{Two ,}φ_R= M_R・ X^TwoFitting
To run. Similarly, plotted points (φ_S) To a cubic function
φ_S= Mx^{Three Or}Fit a quartic function. (viii) Fitted function and phase at each station
(Φ_P, Φ_Q, Φ_R, Φ_S) And the residual (Δφ_P, Δφ_Q, Δφ
_R, Δφ_S). (ix) Residual (Δφ_P, Δφ_Q, Δφ_R, Δφ_S) Based on higher order
Evaluate the aberration. When evaluating high-order aberrations,
May be used.

(2) Second Embodiment FIG. 18 shows a second embodiment of the present invention. In the lens evaluation system 60 shown in this figure, a laser source 61 as a light source emits a laser beam 62. This laser light has coherence, and for example, helium neon laser light can be suitably used. This is the same in the following embodiments.
The emitted laser light 62 is adjusted to a substantially parallel light 64 by a lens 63, and then applied to a reflective diffraction grating 66 by an objective lens 65. Diffracted light 67 from diffraction grating 66
Is incident on the objective lens 65 again. Diffraction grating 66
Is designed such that the 0th-order diffracted light and the + 1st-order diffracted light or the -1st-order diffracted light cause sharing interference on the pupil plane 68 of the objective lens 65. This sharing interference light is returned to a substantially parallel light by the objective lens 65, and the half mirror 69 disposed between the objective lens 65 and the lens 63 converts the light into approximately parallel light.
The direction of 0 ° is changed, and the imaging element 71 is
(For example, a CCD sensor). Image sensor 71
Is connected to the signal processing device 72, the sharing interference image captured by the image sensor 70 is subjected to signal processing by the signal processing device 72, and the processing result is displayed on the display device 73. Then, the diffraction grating 66 is moved in a direction orthogonal to the grating grooves by a moving mechanism 74 having a piezo element, for example.
The defocus amount and various aberrations of the objective lens 65 are evaluated as described above using the display device 2 and the display device 73.
In order to accurately form the sharing interference image on the image sensor 71, another moving mechanism 75 that can move the diffraction grating 66 in the optical axis direction (the left-right direction in FIG. 18) may be provided. In addition, it is preferable that the moving mechanism 75 is configured such that the frame holding the diffraction grating 66 and the base supporting the frame are connected with a plurality of screws, and the position can be adjusted by turning these screws. . In the embodiment described below, various members (for example, a lens, a light source, a diffraction grating, an image sensor, and an optical system including them) are moved and moved.
The mechanism for rotating and tilting may be configured similarly, or may be configured using a piezo element.

(3) Third Embodiment FIG. 19 shows a third embodiment of the present invention. In the lens evaluation system 80 shown in this figure, a laser source 81 as a light source emits a laser beam 82. The emitted laser light 82 is adjusted to a substantially parallel light 84 by a lens 83, and then applied to a transmission diffraction grating 86 by an objective lens 85. The diffracted light 87 from the diffraction grating 86 is incident on a lens 88. The diffraction grating 86 is designed such that the 0th-order diffracted light and the + 1st-order diffracted light or the -1st-order diffracted light cause sharing interference on the pupil plane 89 of the objective lens 65. This sharing interference light returns to substantially parallel light by the lens 88, and is imaged on the imaging element 91 by the imaging lens 90. The image sensor 91 is connected to a signal processing device 92, and the sharing interference image captured by the image sensor 91 is signal-processed by the signal processor 92, and the processing result is displayed on a display device 93. And
A moving mechanism 94 having, for example, a piezo element
Move in the direction perpendicular to the lattice groove (the vertical direction in FIG. 19), and the defocus amount and various aberrations of the objective lens 88 are evaluated using the signal processing device 92 and the display device 93 as described above. In order to accurately form the sharing interference image on the image sensor 91, another moving mechanism 95 that can move the diffraction grating 86 in the optical axis direction (the left-right direction in FIG. 19).
May be provided. Further, another moving mechanism 96 may be provided so that the diffraction grating 86 can be moved together with the lens 88 in the optical axis direction so as to eliminate the evaluated defocus.

(4) Fourth Embodiment FIG. 20 shows a fourth embodiment of the present invention. In a lens adjustment system 100 shown in this figure, a laser source 101 as a light source emits a laser beam 102. The emitted laser light 102 is adjusted to a substantially parallel light 104 by a lens 103, and then a half mirror 105 and a reflection mirror 106.
And an image is formed on the reflection type diffraction grating 108 by the objective lens 107. The diffracted light 109 from the diffraction grating 108 enters the objective lens 107. The diffraction grating 108 converts the 0th-order diffracted light and the + 1st-order or -1st-order diffracted light into the objective lens 10.
The pupil plane 7 is designed to cause sharing interference. This sharing interference light returns to substantially parallel light by the objective lens 107, and is reflected by the reflection mirror 106, the half mirror 10 and the like.
5, an image is formed on the image sensor 111 by the imaging lens 110. The image sensor 111 is connected to the signal processing device 112, and the sharing interference image captured by the image sensor 111 is signal-processed by the signal processor 112, and the processing result is displayed on the display device 113. Then, the diffraction grating 108 is moved by a moving mechanism 114 having a piezo element, for example, in a direction perpendicular to the grating grooves (the left-right direction in FIG. 20), and the signal is processed by the signal processing device 112 and the display device 113 as described above. The focus amount and various aberrations of the objective lens 107 are evaluated. It should be noted that the sharing interference image is
Moving mechanism 116 that can move the diffraction grating 108 in the optical axis direction (vertical direction in FIG. 20) in order to form an image accurately.
May be provided. Also, the optical system 117 including the laser source 101, the lens 103, and the condenser lens 107 as a whole, or the lens source 101 and the like included in the laser source 101, the lens 103, and the like may be used alone to eliminate the evaluated defocus. Another moving mechanism 117 that can move in the direction or in a direction (X, Y direction) perpendicular to the direction may be provided. Further, the lens adjustment system 100 includes an adjustment mechanism 118 that can adjust the tilt of the objective lens in the X and Y directions and the direction (that is, the rotation) about the optical axis, and was evaluated by the signal processing device 112 and the like. The aberration (for example, coma) of the objective lens 107 can be adjusted.

(5) Fifth Embodiment FIG. 21 shows a fifth embodiment of the present invention. In a lens adjustment system 120 shown in this figure, a laser source 121 as a light source emits a laser beam 122. The emitted laser light 122 is adjusted to substantially parallel light 124 by a lens 123, and then applied to a transmission diffraction grating 126 by an objective lens 125. Diffracted light 12 from diffraction grating 126
7 is incident on the lens 128. The diffraction grating 126
Order diffraction light and + 1st order diffraction light or −1st order diffraction light
The pupil plane 8 is designed to cause sharing interference. This sharing interference light returns to substantially parallel light by the lens 128, and is imaged on the imaging element 130 by the imaging lens 129. The image sensor 130 is connected to the signal processing device 131, the sharing interference image captured by the image sensor 130 is signal-processed by the signal processor 131, and the processing result is displayed on the display device 132. Then, the diffraction grating 126 is moved in a direction orthogonal to the grating grooves (the left-right direction in FIG. 21) by, for example, a moving mechanism 133 having a piezo element, and the signal is processed by the signal processing device 131 and the display device 132 as described above. The focus amount and various aberrations of the objective lens 125 are evaluated. In order to accurately form the sharing interference image on the image sensor 130, another moving mechanism 134 that can move the diffraction grating 126 in the optical axis direction (vertical direction in FIG. 21) may be provided. Also, the optical system 135 including the laser source 121, the lens 123, and the objective lens 125 as a whole, or the lens source 101 and the like included in the laser source 121, the lens 123, and the objective lens 125 are used alone in the optical axis direction so as to eliminate the evaluated defocus. Or another moving mechanism 136 that can move in a direction (X, Y directions) orthogonal to the above. Further, the lens adjustment system 120 includes an adjustment mechanism 137 that can adjust the tilt of the objective lens 125 in the X and Y directions and the direction (that is, rotation) about the optical axis.
The aberration (for example, coma) of the objective lens 125 evaluated by the above-described method can be adjusted.

(6) Sixth Embodiment FIG. 22 shows a sixth embodiment of the present invention. In a lens adjustment system 140 shown in this figure, a laser source 141 as a light source emits a laser beam 142. The emitted laser light 142 is expanded into substantially parallel light by the beam expander 143, is reflected by the half mirror 144, and is incident on the objective lens 146 supported by the holding table 145. The objective lens 146 has a flat edge surface 148 around the lens spherical surface 147, and not only the lens spherical surface 147,
Light is also incident on the edge surface 148.

The light incident on the edge surface 148 is
After being reflected at 48 and transmitting through the half mirror 144, it is reflected by another half mirror 149 and is imaged on the image sensor (second image receiver) 151 by the imaging lens 150. Image sensor 1
51 transmits a signal corresponding to the received image to the display device 152. The display device 152 processes a signal from the imaging element 151 and displays an image on the edge surface 148. Therefore,
By looking at the image displayed on the display device 152, it can be determined whether or not the objective lens 146 is accurately arranged with respect to the optical axis 153. When the objective lens 146 is not correctly positioned with respect to the optical axis 153, the holding table moving mechanism 154 is used to move the holding table 145 in the direction of the optical axis 153 and / or.
Alternatively, while moving in a direction perpendicular to this, the holding table 145 is rotated around the optical axis 153 if necessary and / or the inclination with respect to the optical axis 153 is adjusted.

The light incident on the lens spherical surface 147 of the objective lens 146 forms an image on the reflection type diffraction grating 155. The diffracted light from the diffraction grating 155 enters the objective lens 146. As in the above embodiment, the diffraction grating 155 converts the 0th-order diffracted light and the + 1st-order or -1st-order diffracted light into
The pupil plane 6 is designed to cause sharing interference. The sharing interference light returns to the substantially parallel light 156 by the objective lens 146, passes through the half mirrors 144 and 149, and is imaged on the image sensor 158 by the imaging lens 157. The image sensor 158 transmits a signal corresponding to the received image to the signal processing device 159. The signal processing device 159 processes the signal from the image sensor 158 and displays a sharing interference image on the display device 160. Then, various aberrations of the objective lens 146 are evaluated using the signal processing device 159 and the display device 160 as described above. Of these aberrations, the aberration that can be minimized by moving the objective lens 146 is minimized or eliminated by moving, tilting, and rotating the objective lens 146 using the holder moving mechanism 154.

Incidentally, similarly to the above embodiment, the diffraction grating 1
55, a mechanism 161 for moving the diffraction grating 155 in the direction of the optical axis 153, and a mechanism 161 for moving the diffraction grating 155 in a direction orthogonal to the grating.
And a mechanism 163 for adjusting the inclination of the diffraction grating.

It is also desirable that a moving mechanism is provided for lenses other than the objective lens 146, light sources, and the like so that they can be adjusted as needed.

(7) Seventh Embodiment FIG. 23 shows a seventh embodiment of the present invention. In the lens adjustment system 170 shown in this figure, a laser source 171 as a light source emits a laser beam 172. The emitted laser light 172 is expanded into substantially parallel light by the beam expander 173, reflected by the half mirror 174, and incident on the objective lens 176 supported by the holding table 175. The objective lens 176 has a flat edge surface 178 around the lens spherical surface 177, and not only the lens spherical surface 177 but also
Light is also incident on the edge surface 178.

The light incident on the edge surface 178 is
After being reflected at 78 and transmitting through the half mirror 174, an image is formed on an image sensor (second image receiver) 179 by the image forming lens 175. The image sensor 179 transmits a signal corresponding to the received image to the display device 180. The display device 180 processes a signal from the image sensor 179 and displays an image on the edge surface 178. Therefore, by looking at the image displayed on the display device 180, it can be determined whether or not the objective lens 176 is accurately arranged with respect to the optical axis 181. Objective lens 17
6 is not correctly positioned with respect to the optical axis 181, the holding table moving mechanism 182 is used to move the holding table 175 in the direction of the optical axis 181 and / or the direction orthogonal thereto, and if necessary, to hold the table. The table 175 is rotated around the optical axis 181 and / or the inclination with respect to the optical axis 181 is adjusted.

The light incident on the lens spherical surface 177 of the objective lens 176 forms an image on the transmission diffraction grating 183. The diffracted light transmitted through the diffraction grating 183 enters the lens 184. Similar to the above embodiment, the diffraction grating 183 is designed so that the 0th-order diffracted light and the + 1st-order diffracted light or the -1st-order diffracted light cause sharing interference on the pupil plane of the lens 184. This sharing interference light returns to substantially parallel light by the lens 184, and is imaged on the image sensor 186 by the imaging lens 185. The image sensor 186 transmits a signal corresponding to the received image to the signal processing device 187. The signal processing device 187
The signal from the image sensor 186 is processed, and a sharing interference image is displayed on the display device 188. Then, various aberrations of the objective lens 176 are evaluated using the signal processing device 187 and the display device 188 as described above. Of these aberrations, the aberration that can be minimized by moving the objective lens 176 is minimized or eliminated by moving, tilting, and rotating the objective lens 176 using the holding table moving mechanism 182.

Incidentally, similarly to the above embodiment, the diffraction grating 1
In addition to the mechanism 189 for moving the diffraction grating 183 in a direction orthogonal to the grating, a mechanism 19 for moving the diffraction grating 183 together with the lens 184 in the direction of the optical axis 181 is provided.
0, a mechanism 191 for rotating the diffraction grating 183, and a mechanism (not shown) for adjusting the inclination of the diffraction grating may be provided.

It is desirable to provide a moving mechanism for other lenses, light sources, and the like so that they can be adjusted as needed.

(8) Eighth Embodiment FIG. 24 shows an eighth embodiment of the present invention. In the lens adjustment system 200 shown in this figure, a laser beam 201 is incident on an objective lens 203 substantially parallel to an optical axis 202. The light transmitted through the objective lens 203 is transmitted through a transmission diffraction grating 204.
Is imaged. Diffracted light generated by the diffraction grating 204 is incident on a lens 205. Similar to the above-described embodiment, the diffraction grating 204 is designed so that the 0th-order diffracted light and the + 1st-order diffracted light or the -1st-order diffracted light cause sharing interference on the pupil plane of the lens 205. This sharing interference light is returned to substantially parallel light by the lens 205, and a part thereof is
And is imaged on the image sensor 208 by the imaging lens 207. The imaging element 208 transmits a signal corresponding to the received image to the display device 209. The display device 209 processes a signal from the imaging element 208 and displays an image of light transmitted through the lens 205. Therefore, by looking at the image displayed on the display device 209, it can be determined whether or not the optical axis of the objective lens 203 and the like is correctly aligned with the optical axis 202. For example, if the objective lens 203 is not properly positioned with respect to the optical axis 202,
The optical axis of the objective lens 203 is made coincident with the optical axis 202 by using a lens moving mechanism 210 for moving in a direction perpendicular to the optical axis.

The light transmitted through the half mirror 206 is imaged on the image sensor 212 by the image forming lens 211. The image sensor 212 converts a signal corresponding to the received image into a signal
Send to 3. The signal processing device 213 includes an image sensor 212
Process the signal from the display device and display the sharing interference image on the display device 2.
14 is displayed. Then, various aberrations of the objective lens 203 are evaluated using the signal processing device 213 and the display device 214 as described above. Of these aberrations, the aberration that can be minimized by moving the objective lens 203 is:
A mechanism 215 for moving the objective lens 203 in the optical axis direction,
The objective lens 203 is minimized or eliminated by moving, tilting, and rotating the objective lens 203 using a mechanism 216 for adjusting the tilt of the objective lens 203 and, if necessary, a lens moving mechanism 210.

Incidentally, similarly to the above embodiment, the diffraction grating 2
In addition to the mechanism 217 for moving the diffraction grating 204 in a direction perpendicular to the grating, the mechanism 21 for moving the diffraction grating 217 together with the lens 205 in the optical axis 202 direction.
8. A mechanism (not shown) for rotating and tilting the diffraction grating 204 may be provided.

It is desirable to provide a moving mechanism for other lenses, light sources, and the like so that they can be adjusted as needed.

(9) Ninth Embodiment FIG. 25 shows a ninth embodiment of the present invention. In the lens adjustment system 220 shown in this figure, the laser light 221 is incident on the objective lens 223 substantially parallel to the optical axis 222. The light transmitted through the objective lens 223 is transmitted to the transmission type diffraction grating 224.
Is imaged. The diffracted light generated by the diffraction grating 224 enters the lens 225. Similarly to the above embodiment, the diffraction grating 224 is designed such that the 0th-order diffracted light and the + 1st-order diffracted light or the -1st-order diffracted light cause sharing interference on the pupil plane of the lens 225. This sharing interference light returns to substantially parallel light by the lens 225 and is imaged on the image sensor 227 by the imaging lens 226. The imaging element 227 transmits a signal corresponding to the received image to the signal processing device 228. The signal processing device 228 processes a signal from the image sensor 227,
The sharing interference image is displayed on the display device 229. Then, various aberrations of the objective lens 223 are evaluated using the signal processing device 228 and the display device 229 as described above. Among these aberrations, the aberration that can be minimized by moving the objective lens 223 includes a mechanism 230 for moving the objective lens 223 in the optical axis direction, a mechanism 231 for moving the objective lens 223 in a direction perpendicular to the optical axis, and an objective lens. By moving and tilting the objective lens 223 by using the mechanism 232 for adjusting the tilt of the 223, it is minimized or eliminated.

Further, by looking at the image displayed on the display device 229, the image pickup device 22 is positioned at the image forming position of the image forming lens 226.
7 can be determined as to whether they are correctly arranged. When the image sensor 227 is not located at the image forming position, the moving mechanism 2
At 28, the image sensor 227 can be moved in the optical axis direction and adjusted to the correct position. Further, similarly to the above-described embodiment, a diffraction grating 224 is provided in addition to a mechanism 229 for moving the diffraction grating 224 in a direction orthogonal to the grating.
23 for moving the lens with the lens 225 in the optical axis direction
A mechanism (not shown) for rotating and tilting the diffraction grating 224 may be provided. Further, it is desirable to provide a moving mechanism for other lenses, light sources, and the like so that they can be adjusted as needed.

(10) Diffraction Grating As described above, the diffraction grating used in the present invention includes a reflection type diffraction grating and a transmission type diffraction grating. As shown in FIG. 26, such a diffraction grating is provided on a surface of a substrate 241 formed of a material (for example, polycarbonate) having a predetermined refractive index (nk) at a predetermined interval (grating pitch: Pk).
A lattice groove 242 having a predetermined depth (lattice depth: dk) and a predetermined width (lattice width: Pm) is formed in a predetermined direction. In the case of a reflective diffraction grating, a thin reflective film (not shown) is formed on the surface on which the grating grooves 242 are formed by depositing a reflective material such as aluminum. Although not shown in FIG. 26, the surface of the diffraction grating on which the grating is formed is preferably covered with a cover made of a suitable material (for example, polycarbonate). Further, a cover glass may be provided near the grating surface of the diffraction grating to protect the diffraction grating. Further, an optical disk or a part thereof can be used as the reflection type diffraction grating.

These grating pitches Pk and the like greatly affect the contrast between the 0th-order diffracted light and the ± 1st-order diffracted light, the size of the sharing interference image, and the diffracted light to be shared. Specifically, the grating pitch Pk affects the diffraction angle, and the smaller the grating pitch Pk, the larger the diffraction angle of the diffracted light. As a result, the sharing interference image becomes smaller. Conversely, as the grating pitch Pk increases, the diffraction angle decreases, and the sharing interference image increases. In addition, the size of the sharing interference image also depends on the wavelength λ of the light and the numerical aperture A of the condenser lens (objective lens) (= sin θs θs: the incident ray angle of light incident on the diffraction grating from the condenser lens). I do.

The intensity of the diffracted light and the contrast of the shearing interference image depend on the grating depth dk of the diffraction grating, the grating duty ratio: Pm / Pk, the light wavelength λ, and the refractive index nk of the diffraction grating.

From the above, as shown in FIG.
When a sharing interference image is obtained by interfering the + 1st order diffracted light with the + 1st order diffracted light and the + 1st order diffracted light, it is preferable to design the diffraction grating so as to satisfy the following conditions. 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (8 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: lattice pitch dk: lattice Depth du: Grating duty ratio (= width of grating groove / grating pitch) A: Numerical aperture of diffraction grating (= sin θs θs: incident ray angle of light incident on the diffraction grating from the condenser lens) nk: Refraction of diffraction grating Rate λ: wavelength of light The most preferable condition is Pk · (A / λ) = 1 dk · (nk−1) · (8 / λ) = 1 d = 0.5.

As shown in FIG. 28, the + 1st-order diffracted light and -1
In order to obtain a sharing interference image by interfering with the next-order diffracted light, it is necessary to design the diffraction grating under conditions that do not generate the zero-order diffracted light, and the conditions in this case are as follows. 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (4 / λ) ≦ 1.2 0.4 ≦ du ≦ 0.6 The most preferable condition is Pk · sin (θs / 2) / λ = 1 dk · (nk−1) · (4 / λ) = 1 du = 0.5.

However, the diffraction grating is not necessarily restricted by the above conditions, and may be designed under the following conditions, for example.

Design condition 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (4 / λ) ≦ 2 0.2 ≦ du ≦ 0.8

Design condition 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (4 / λ) ≦ 1.2 0.4 ≦ du ≦ 0.6

In the above description, the diffraction grating is moved in the direction orthogonal to the grating direction (grating groove) in the embodiment of the present invention. The same operation and effect can be obtained even by moving in a direction oblique to the lattice direction.

[0102]

As is apparent from the above description, according to the lens evaluation method, the evaluation apparatus, the adjustment method, and the adjustment apparatus according to the present invention, the phase of the light intensity change at a plurality of points of the sharing interference image is determined. This is a simple method of determining the characteristics of the lens (defocus, coma,
Astigmatism, spherical aberration, and higher-order aberrations). The number of points for obtaining the phase of the light intensity change is a minimum of two.
In this case, the characteristics of the lens can be evaluated and adjusted in a short time.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a conventional lens aberration detection method (jitter method) and apparatus, and an explanatory diagram of its principle.

FIG. 2 is a graph illustrating an aberration adjustment method using the apparatus shown in FIG.

FIG. 3 is a schematic diagram of another conventional lens aberration detection method (light intensity measurement method) and apparatus, and an explanatory diagram of the principle thereof.

4A and 4B are diagrams showing images obtained by the lens aberration detecting method shown in FIG. 3, wherein FIG. 4A shows an image before adjustment and FIG. 4B shows an image after adjustment.

FIG. 5 is a diagram showing a schematic configuration of a lens aberration evaluation device according to the first embodiment of the present invention.

FIG. 6 is a view showing diffracted light generated from a reflection type diffraction grating.

FIG. 7 is a view showing a sharing interference image formed on an image sensor.

FIG. 8 is a diagram showing measurement points on a sharing interference image.

FIG. 9 is a view showing a light intensity change in measurement on the sharing interference image shown in FIG. 8;

10A and 10B are diagrams showing the wavefront shape of aberration, where FIG. 10A shows a defocus amount, FIG. 10B shows coma aberration, FIG.
(D) is a wavefront of spherical aberration.

11A and 11B are diagrams showing interference fringes appearing on sharing interference, wherein FIG. 11A shows a defocus amount, FIG. 11B shows coma aberration (coma R component), FIG. 11C shows coma aberration (coma T component), and FIG. ) Indicates astigmatism, and (E) indicates interference fringes of spherical aberration.

12A and 12B are diagrams for explaining a method of evaluating a defocus amount, where FIG. 12A is a graph showing a measurement point on sharing interference, and FIG. 12B is a graph obtained by fitting a phase as a linear function of measurement point coordinates.

FIG. 13 is a view for explaining a method of evaluating a top R component;
(A) is a measurement point on the sharing interference, and (B) is a graph in which the phase is fitted with a quadratic function of the measurement point coordinates.

FIG. 14 is a diagram for explaining a method of evaluating a frame T component;
(A) is a measurement point on the sharing interference, and (B) is a graph in which the phase is fitted with a quadratic function of the measurement point coordinates.

FIG. 15 is a diagram illustrating a method for evaluating astigmatism;
(A) is a measurement point on the sharing interference, and (B) is a graph in which the phase is fitted with a linear function of the measurement point coordinates.

FIG. 16 is a diagram illustrating a method for evaluating spherical aberration.
(A) is a measurement point on sharing interference, and (B) is a graph in which the phase is fitted with a cubic function of the measurement point coordinates.

FIG. 17 is a diagram illustrating a method for evaluating higher-order aberrations.
(A) is a measurement point on sharing interference, and (B) to (E) are graphs in which the phase is fitted with a function of the measurement point coordinates.

FIG. 18 is a diagram showing a schematic configuration of a lens aberration evaluation device according to a second embodiment of the present invention.

FIG. 19 is a diagram showing a schematic configuration of a lens aberration evaluation device according to a third embodiment of the present invention.

FIG. 20 is a diagram illustrating a schematic configuration of a lens adjustment device according to a fourth embodiment of the present invention.

FIG. 21 is a diagram illustrating a schematic configuration of a lens adjustment device according to a fifth embodiment of the present invention.

FIG. 22 is a diagram illustrating a schematic configuration of a lens aberration evaluation device according to a sixth embodiment of the present invention.

FIG. 23 is a view showing a schematic configuration of a lens aberration evaluation device according to a seventh embodiment of the present invention.

FIG. 24 is a diagram showing a schematic configuration of a lens adjustment device according to an eighth embodiment of the present invention.

FIG. 25 is a diagram showing a schematic configuration of a lens adjustment device according to a ninth embodiment of the present invention.

FIG. 26 is a partially enlarged sectional view of a diffraction grating.

FIG. 27 is a view showing a sharing interference image of the 0th-order diffracted light and the + 1st-order and -1st-order diffracted lights.

FIG. 28 is a view showing a sharing interference image of + 1st-order and -1st-order diffracted light.

FIG. 29 is a diagram showing a diffraction grating in which a grating groove is formed in a specific direction and a diffraction grating in which a grating groove is formed in an oblique direction that forms an angle of 45 ° with the specific direction.

[Explanation of symbols]

31... 0th-order diffracted light, 32... + 1st-order diffracted light, 50.

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Kanji Nishii 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F-term (reference) 2G086 HH06 HH07 5D119 AA38 DA20 JA02 JA43 NA05 PA05

Claims (84)

[Claims] 1. A step of diffracting light emitted from a lens and causing two diffracted lights of different orders to interfere with each other to obtain a sharing interference image, and (b) a step of changing the phase of the diffracted light. (C) obtaining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image; Obtaining a characteristic of the lens based on the phase. 2. A step of diffracting light emitted from a lens and causing two diffracted lights of different orders to interfere with each other to obtain a sharing interference image, and (b) a step of changing the phase of the diffracted light. (C) obtaining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image; When the measuring point position is X and the phase is Y, the phase Y is approximated by a function of the measuring position X, and the characteristic of the lens is evaluated by the coefficient value of the function. Evaluation method. 3. A lens evaluation method, wherein a Schering interference image of the two diffracted lights is transmitted through the lens. (A) condensing light emitted from a light source with an objective lens, projecting the condensed light onto a reflection type diffraction grating, and diffracting two different orders of light reflected from the reflection type diffraction grating. The light is converted into substantially parallel light by the objective lens, the substantially parallel light is condensed by a condenser lens, and the condensed light is imaged on an image receiving surface. (B) moving the diffraction grating in a direction having a directional component in a direction orthogonal to the grating direction;
Changing the phase of the diffracted light; and (c) determining the light intensity change at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image. A method for evaluating a lens, comprising: a step of obtaining a phase; and (d) a step of obtaining characteristics of the objective lens based on the phase. 5. A light emitted from a light source is condensed by an objective lens, and the condensed light is projected on a reflection type diffraction grating, and two diffraction lights of different orders reflected from the reflection type diffraction grating. The light is converted into substantially parallel light by the objective lens, the substantially parallel light is condensed by a condenser lens, and the condensed light is imaged on an image receiving surface. (B) moving the diffraction grating in a direction having a directional component in a direction orthogonal to the grating direction;
Changing the phase of the diffracted light; and (c) determining the light intensity change at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the sharing interference image. And (d) when the measurement point position is X and the phase is Y, the phase Y is approximated by a function of the measurement position X, and the optical value of the objective lens is calculated by the coefficient value of the function. And a step of evaluating characteristics. 6. (a) Light emitted from a light source is condensed by an objective lens, and the condensed light is projected on a transmission type diffraction grating, and two diffractions of different orders transmitted through the transmission type diffraction grating. The light is converted into substantially parallel light by a lens, the substantially parallel light is condensed by a condenser lens, and the condensed light is imaged on an image receiving surface. (B) moving the diffraction grating in a direction having a direction component perpendicular to the grating direction to change the phase of the diffracted light; and (c) obtaining the sharing interference image. Obtaining a phase of a light intensity change at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights in the image; and (d) the objective lens based on the phase. Determining a characteristic of the lens. 7. (a) Light emitted from a light source is condensed by an objective lens, the condensed light is projected on a transmission type diffraction grating, and two diffractions of different orders transmitted through the transmission type diffraction grating. The light is converted into substantially parallel light by a lens, the light converted into substantially parallel light is condensed by a condenser lens, the condensed light is imaged on an image receiving surface, and the two diffracted lights are formed on the image receiving surface. (B) moving the diffraction grating in a direction having a direction component perpendicular to the grating direction to change the phase of the diffracted light; and (c) changing the phase of the shearing interference image. Obtaining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights; and (d) setting the measurement point position to X and the phase to Y
When the phase Y is approximated by a function of the measurement position X,
Evaluating the optical characteristics of the objective lens with the coefficient value of the function. 8. The two diffracted lights are 0th-order diffracted light and ± 1
The method for evaluating a lens according to any one of claims 1 to 7, wherein the one of the first-order diffracted lights, or the + 1st-order diffracted light and the -1st-order diffracted light. 9. The optical characteristic to be evaluated is any one of a defocus amount, a coma aberration, a spherical aberration, an astigmatism, and an aberration other than these aberrations. Evaluation method for any of the lenses. 10. A light diffracted from a lens is diffracted, and either one of a 0th-order diffracted light and ± 1st-order diffracted light, or +
Obtaining a shared interference image of the first-order diffracted light and the -1st-order diffracted light on the image receiving surface; (b) changing the phase of the diffracted light; Obtaining a phase of a change in light intensity at a plurality of measuring points on a line segment passing through the optical axis; (d)
Assuming that the measurement point position is X and the phase is Y, the phase Y is approximated by a linear function of the measurement position X or a function having a first or higher order, and the above-mentioned is calculated by a first-order coefficient value of the approximate function. A method for evaluating a lens, comprising a step of evaluating a defocus amount of an optical system. 11. (a) Diffracting light emitted from a lens, and selects one of 0th-order diffracted light and ± 1st-order diffracted light, or +
Obtaining a shared interference image of the first-order diffracted light and the -1st-order diffracted light on the image receiving surface; (b) changing the phase of the diffracted light; Calculating a phase of a change in light intensity at a plurality of measuring points on a vertical bisector of a line connecting the optical axes; and (d) when the measuring point position is X and the phase is Y , The phase Y is approximated by a quadratic function of the measurement position X,
A method for evaluating a lens, comprising a step of evaluating coma with a quadratic coefficient value of the quadratic function. 12. (a) The light emitted from the lens is diffracted, and either one of 0-order diffracted light and ± 1st-order diffracted light, or +
Obtaining a shared interference image of the first-order diffracted light and the -1st-order diffracted light on the image receiving surface; (b) changing the phase of the diffracted light; Obtaining a phase of a change in light intensity at the measurement point by a plurality of measurements on two oblique lines passing through a midpoint of a line segment connecting the optical axes and forming a predetermined angle in a positive direction and a negative direction with respect to the line segment; And (d) for each of the two oblique lines, the measuring point position is X and the phase is Y, and the phase Y is approximated by a quadratic function or a cubic function of the measuring position X, and the quadratic function or cubic function is obtained. A method for evaluating a lens, comprising a step of evaluating coma using a second-order coefficient value of a function. 13. (a) The light emitted from the lens is diffracted, and either one of 0-order diffracted light and ± 1st-order diffracted light or +
Obtaining a shared interference image of the first-order diffracted light and the -1st-order diffracted light on the image receiving surface; (b) changing the phase of the diffracted light; Light intensity change at the measurement point in a plurality of measurements on a vertical bisector passing through the midpoint of the line segment connecting the optical axis and two oblique lines forming a predetermined angle in the positive and negative directions with respect to the line segment And (d) obtaining, with respect to the vertical bisector, the measuring point position as X and the phase as Y, and the phase Y is approximated by a quadratic function or a cubic function of the measuring position X. A quadratic coefficient value of the quadratic function or the cubic function, and for the two oblique lines, the measuring point position is X, the phase is Y, and the phase Y is a quadratic function or a cubic function of the measuring position X. Coma aberration using the difference between the quadratic function or the quadratic coefficient of the cubic function obtained by approximation Evaluating the lens. 14. (a) Diffracting light emitted from a lens, and selects one of 0th-order diffracted light and ± 1st-order diffracted light, or +
Obtaining a sharing interference image of the first-order diffraction light and the -1st-order diffraction light on the image receiving surface; (b) rotating the sharing direction of the sharing interference image; and (c) moving the diffraction grating to obtain Changing the phase of the diffracted light;
(D) obtaining a phase of a light intensity change at a plurality of measurement points on a perpendicular bisector of a line connecting the optical axes of the diffracted light in the sharing interference image; The point position is X, the phase is Y, and the phase Y is approximated by a linear function of the measurement position X or a function having a first or higher order. A method for evaluating a lens, comprising a step of evaluating point aberration. 15. The lens evaluation method according to claim 15, wherein the step of rotating the sharing direction includes a step of rotating the diffraction grating by a predetermined angle. 16. The lens evaluation method according to claim 15, wherein the step of rotating the sharing direction includes a step of rotating the lens by a predetermined angle. 17. The step of rotating the sharing direction includes: diffracting light using a first diffraction grating having a grating groove formed in a first direction; and grating the light in a direction different from the first direction. Diffracting light using a second diffraction grating having a groove formed therein. 18. (a) Diffracting light emitted from a lens, and selects one of 0th-order diffracted light and ± 1st-order diffracted light, or +
Obtaining a shared interference image of the first-order diffracted light and the -1st-order diffracted light on the image receiving surface; (b) changing the phase of the diffracted light; Obtaining a phase of a change in light intensity at a plurality of measuring points on a line segment passing through the optical axis; (d)
The measurement point position is X, the phase is Y, and the phase Y is approximated by a cubic function or a quartic function of the measurement position X, and the spherical aberration of the optical system is calculated by a cubic coefficient value of the cubic function or quaternary function. A method for evaluating a lens, comprising the step of evaluating 19. (a) Diffracting light emitted from a lens, and selects one of 0-order diffracted light and ± 1st-order diffracted light, or +
(B) changing the phase of the diffracted light; and (c) changing the phase of the diffracted light; and (c) changing the phase of the diffracted light. Calculating a first phase of a change in light intensity at the first measurement point at a plurality of first measurement points on a line segment connecting the optical axes of the diffracted light; The second at the second station
A second phase of the light intensity change at the measurement point is determined. A plurality of third measurement points on a third oblique line passing through the midpoint of the line segment and forming a predetermined angle in the positive direction with respect to the line segment Calculating a third phase of the light intensity change at the third measurement point at a point; a plurality of fourth oblique lines passing through the midpoint of the line segment and forming a predetermined angle in the negative direction with respect to the line segment; Obtaining a fourth phase of the light intensity change at the fourth measurement point at the fourth measurement point;
(D) The first measurement point position is X and the first phase is Y
The first phase Y is approximated by a first function F of a first measurement position X, the second measurement point position is X, the second phase is Y, and the second phase Y Is approximated by the second function F of the second measurement position X, the third measurement point position is X, the third phase is Y, and the third phase Y is the third measurement position X. Approximate by a third function F, and the fourth measurement point position is X,
The fourth phase is defined as Y, the fourth phase Y is approximated by a fourth function F at a fourth measurement position X, and a residual Δ between the first function F and the first phase Y, The residual Δ between the second function F and the second phase Y, the residual Δ between the third function F and the third phase Y, and the residual Δ between the fourth function F and the fourth phase Y Residual Δ
Evaluating the higher-order aberrations of the optical system based on the above method. 20. An apparatus for evaluating a condensing lens included in an optical system, comprising: (a) diffracting light transmitted through the condensing lens, and emitting sharing interference light of two diffracted lights of different orders. (B) a moving mechanism for moving the diffraction grating, (c) a receiver for receiving the sharing interference light, and (d) an interference image of the sharing interference light received by the receiver. Characteristic detection for obtaining the phase of the light intensity change at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes of the two diffracted lights, and obtaining the characteristics of the condenser lens based on the phase A lens evaluation device, comprising: 21. The lens evaluation apparatus according to claim 21, wherein said diffraction grating is a reflection type diffraction grating or a transmission type diffraction grating. 22. An apparatus for evaluating a condensing lens included in an optical system, comprising: (a) a light source for inputting substantially parallel light to the condensing lens; and (b) reflecting light transmitted through the objective lens. A reflection type diffraction grating which diffracts and makes the sharing interference light of two diffracted lights of different orders incident on the condenser lens; (c) a moving mechanism for moving the diffraction grating; and (d) the condenser lens. An imaging lens that forms an image of the sharing interference light transmitted through the imaging lens; (e) an image receiving body that receives the formed imaging interference light;
In the sharing interference image received by the image receiver, the phase of the light intensity change is determined at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes of the two diffracted lights, and the phase is determined based on the phase. And a characteristic detector for determining characteristics of the condensing lens. 23. The lens adjusting device according to claim 21, further comprising a mechanism for moving the image receiving body in an optical axis direction. 24. The apparatus according to claim 21, further comprising a mechanism for moving the diffraction grating in an optical axis direction.
Any one of the lens adjusting devices. 25. The apparatus according to claim 21, further comprising a mechanism for rotating the diffraction grating around an optical axis.
4. The lens adjusting device according to any one of the above items 4. 26. The characteristic detector obtains a phase of a change in light intensity at a plurality of measurement points on a line connecting the optical axes of the diffracted light in the sharing interference image, and calculates the measurement point position by X. The phase is set to Y, the phase Y is approximated by a linear function of a measurement position X, and the defocus amount of the optical system is evaluated by a linear coefficient value of the linear function. 21. A lens evaluation device according to any one of 21 to 26. 27. The characteristic detector, wherein, in the shearing interference image, a predetermined angle passes through a midpoint of a line segment connecting the optical axes of the diffracted lights and in a positive direction and a negative direction with respect to the line segment. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on the two oblique lines, and the measurement point position is X, the phase is Y, and the phase Y is the measurement position X for each of the two oblique lines. 23. The lens evaluation according to claim 17, wherein a coma aberration is evaluated using a quadratic function or a cubic function of approximation, and using a quadratic coefficient value of the quadratic function or cubic function. apparatus. 28. The characteristic detector, wherein in the shearing interference image, a perpendicular bisector passing through a midpoint of a line connecting the optical axes of the diffracted light, and a positive direction and a negative direction with respect to the line segment. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on two oblique lines forming a predetermined angle, and the measurement point position is X, the phase is Y, and the phase is A quadratic or cubic coefficient value of the quadratic or cubic function obtained by approximating Y with a quadratic or cubic function of the measurement position X, and, for the two oblique lines, the measuring point position is X and the phase is Y And evaluating the coma aberration using a difference between the phase Y and a quadratic function value of the quadratic function or the cubic function obtained by approximating the phase Y with a quadratic function or a cubic function of the measurement position X. The lens evaluation device according to any one of claims 21 to 26, wherein: 29. The method according to claim 29, wherein the predetermined angle is 30 ° to 60 °.
30. The lens evaluation device according to claim 28, wherein the lens evaluation device has the following range. 30. The characteristic detector determines a phase of a change in light intensity at a plurality of measurement points on a vertical bisector of a line connecting the optical axes of the diffracted light in the sharing interference image. The measurement point position is X and the phase is Y, and the phase Y is approximated by a linear function of the measurement position X, and the astigmatism of the optical system is evaluated by a linear coefficient value of the linear function. The lens evaluation device according to any one of claims 21 to 26, wherein: 31. The characteristic detector obtains a phase of a change in light intensity at a plurality of measurement points on a line segment passing through the optical axis of the diffracted light in the sharing interference image, The position is X, the phase is Y, the phase Y is approximated by a cubic function or a quartic function of the measurement position X, and the spherical aberration of the optical system is evaluated by a cubic coefficient value of the cubic function or quartic function. The lens evaluation device according to any one of claims 21 to 26, wherein: 32. The characteristic detector, wherein: in the shearing interference image: light intensity at a plurality of first measurement points on a line connecting the optical axes of the two diffracted lights at the first measurement point; Determining a first phase of the change; a second phase at a plurality of second measurement points on a vertical bisector of said line segment;
A second phase of the light intensity change at the measurement point is determined. A plurality of third measurement points on a third oblique line passing through the midpoint of the line segment and forming a predetermined angle in the positive direction with respect to the line segment Calculating a third phase of the light intensity change at the third measurement point at a point; a plurality of fourth oblique lines passing through the midpoint of the line segment and forming a predetermined angle in the negative direction with respect to the line segment; The fourth phase of the light intensity change at the fourth measurement point is determined at the fourth measurement point, and the first measurement point position is X, the first phase is Y, and the first phase Y Is approximated by a first function F of a first measurement position X, the second measurement point position is X, the second phase is Y, and the second phase Y is a second measurement position X Approximate by a second function F, X is the third measurement point position, Y is the third phase, and the third phase Y is approximated by a third function F of the third measurement position X. The fourth station position , X is the fourth phase, and the fourth phase Y is approximated by a fourth function F at a fourth measurement position X. The remaining of the first function F and the first phase Y Difference Δ, residual Δ between the second function F and the second phase Y, residual Δ between the third function F and the third phase Y, and the fourth function F and the fourth phase 27. The lens evaluation apparatus according to claim 21, wherein a higher-order aberration of the optical system is evaluated based on a residual Δ with respect to Y. 33. The diffraction grating, wherein 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (8 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: light incident on the diffraction grating from the condenser lens 30. The lens evaluation apparatus according to claim 17, wherein the following condition is satisfied: nk: refractive index of the diffraction grating λ: wavelength of light. 34. The diffraction grating, wherein 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (4 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: light incident on the diffraction grating from the condenser lens 34. The lens evaluation apparatus according to claim 21, wherein the following condition is satisfied: nk: refractive index of the diffraction grating λ: wavelength of light. 35. The diffraction grating, wherein 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (4 / λ) ≦ 1.20 0.4 ≦ du ≦ 0.6 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: diffraction grating from condensing lens 34. The lens evaluation apparatus according to claim 21, wherein the following condition is satisfied: nk: refractive index of the diffraction grating λ: wavelength of light. 36. The diffraction grating, wherein 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (2 / λ) ≦ 1.20 0.4 ≦ du ≦ 0.6 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: diffraction grating from condensing lens 34. The lens evaluation apparatus according to claim 21, wherein the following condition is satisfied: nk: refractive index of the diffraction grating λ: wavelength of light. 37. An apparatus for adjusting a condenser lens included in an optical system, comprising: (a) diffracting light transmitted through the condenser lens and emitting sharing interference light of two diffracted lights of different orders. (B) a mechanism for moving the diffraction grating, (c) a receiver for receiving the sharing interference light, and (d) an interference image of the sharing interference light received by the receiver. A characteristic detector for determining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through the midpoint of a line segment connecting the optical axes of the two diffracted lights, and determining a characteristic of the condenser lens based on the phase. And (e) an adjusting device for a lens, comprising: an adjusting mechanism for adjusting a position of the condenser lens based on a detection result of the characteristic detector. 38. An apparatus for adjusting a condensing lens included in an optical system, comprising: (a) diffracting light transmitted through the condensing lens, and emitting sharing interference light of two diffracted lights of different orders. (B) a mechanism for moving the diffraction grating, (c) a receiver for receiving the sharing interference light, and (d) an interference image of the sharing interference light received by the receiver. A characteristic detector for determining a phase of a change in light intensity at a plurality of measurement points on a measurement line passing through the midpoint of a line segment connecting the optical axes of the two diffracted lights, and determining a characteristic of the condenser lens based on the phase. (E) a second image receiving member for receiving reflected light or transmitted light from the condenser lens, and (f)
A lens adjustment device comprising a lens adjustment mechanism for adjusting the position of the condenser lens based on information on light received by the second image receiving member. 39. The method according to claim 38, wherein the condensing lens has an edge surface around the lens surface, and the second image receiver receives reflected light or transmitted light from the edge surface.
Ninth lens adjusting device. 40. The apparatus according to claim 38, wherein the diffraction grating is a reflection type diffraction grating. 41. The apparatus according to claim 38, wherein the diffraction grating is a transmission diffraction grating. 42. The lens adjustment device according to claim 38, wherein the adjustment mechanism includes a mechanism for moving the condenser lens in the optical axis direction. 43. The lens adjusting device according to claim 38, wherein the adjusting mechanism includes a mechanism for moving the condenser lens in a direction orthogonal to the optical axis. 44. The lens adjusting device according to claim 38, wherein the adjusting mechanism includes a mechanism for rotating the condenser lens around an optical axis. 45. The lens adjusting device according to claim 38, wherein the characteristic detecting device includes a mechanism for moving the image receiving body in an optical axis direction. 46. The apparatus according to claim 38, further comprising a mechanism for moving said diffraction grating in an optical axis direction.
Adjustment device for any of the lenses. 47. The apparatus according to claim 38, further comprising a mechanism for rotating said diffraction grating around an optical axis.
0 lens adjusting device. 48. An apparatus for adjusting a condenser lens included in an optical system, comprising: (a) a light source; and (b) a lens which converts light emitted from the light source into substantially parallel light and enters the condenser lens. (C) a reflection type diffraction grating that reflects and diffracts the light condensed by the condensing lens, and that makes the sharing interference light of two diffracted lights of different orders incident on the condensing lens; An imaging lens that forms an image of the sharing interference light emitted from the condenser lens; and (e) an image receiving body that receives the formed sharing interference light;
(F) In the sharing interference image received by the image receiving body, a phase of a light intensity change is obtained at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights. And a characteristic detector for obtaining the characteristics of the condenser lens based on the above. 49. An apparatus for adjusting a condenser lens included in an optical system, comprising: (a) a light source; and (b) a lens which makes light emitted from the light source substantially parallel and enters the condenser lens. (C) a transmission diffraction grating that transmits and diffracts the light condensed by the condensing lens, and that enters a second condensing lens with sharing interference light of two diffracted lights of different orders; d) an imaging lens that forms an image of the sharing interference light emitted from the second condenser lens;
(F) in a sharing interference image received by the image receiving body, an image receiving body that receives the imaged sharing interference light, and on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights. A characteristic detector for obtaining a phase of a change in light intensity at a plurality of measurement points, and obtaining a characteristic of the condenser lens based on the phase. 50. The characteristic detector determines a phase of a change in light intensity at a plurality of measurement points on a line connecting the optical axes of the diffracted light in the sharing interference image, and determines the position of the measurement point as X. The phase is set to Y, the phase Y is approximated by a linear function of a measurement position X, and the defocus amount of the optical system is evaluated by a linear coefficient value of the linear function. 34. A lens adjusting device according to any one of 34 to 46. 51. The characteristic detector, wherein in the shearing interference image, a predetermined angle in a positive direction and a negative direction with respect to the line segment passes through a midpoint of a line segment connecting the optical axes of the diffracted light. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on the two oblique lines, and the measurement point position is X, the phase is Y, and the phase Y is the measurement position X for each of the two oblique lines. 47. The lens adjustment according to any one of claims 34 to 46, wherein approximation is made by a quadratic function or a cubic function, and coma aberration is evaluated using a secondary coefficient value of the quadratic function or the cubic function apparatus. 52. The characteristic detector, wherein in the shearing interference image, a perpendicular bisector passing through a midpoint of a line connecting the optical axes of the diffracted light, and a positive direction and a negative direction with respect to the line segment. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on two oblique lines forming a predetermined angle, and the measurement point position is X, the phase is Y, and the phase is A quadratic or cubic coefficient value of the quadratic function or cubic function obtained by approximating Y with a quadratic or cubic function of the measurement position X; And evaluating the coma aberration using a difference between the phase Y and a quadratic function value of the quadratic function or the cubic function obtained by approximating the phase Y with a quadratic function or a cubic function of the measurement position X. The lens adjustment device according to any one of claims 34 to 46. 53. The predetermined angle is from 30 ° to 60 °.
The lens adjustment device according to claim 53, wherein the lens adjustment device has a range of: 54. The characteristic detector obtains a phase of a change in light intensity at a plurality of measurement points on a vertical bisector of a line connecting the optical axes of the diffracted light in the sharing interference image. The measurement point position is X and the phase is Y, and the phase Y is approximated by a linear function of the measurement position X, and the astigmatism of the optical system is evaluated by a linear coefficient value of the linear function. The lens adjusting device according to any one of claims 38 to 50, characterized in that: 55. The characteristic detector obtains a phase of a change in light intensity at a plurality of measurement points on a line segment passing through the optical axis of the diffracted light in the sharing interference image, The position is X, the phase is Y, the phase Y is approximated by a cubic function or a quartic function of the measurement position X, and the spherical aberration of the optical system is evaluated by a cubic coefficient value of the cubic function or quartic function. The lens adjusting device according to any one of claims 38 to 50, characterized in that: 56. The characteristic detector, wherein: in the shearing interference image: at a plurality of first measurement points on a line connecting the optical axes of the two diffracted lights, the light intensity at the first measurement point; Determining a first phase of the change; a second phase at a plurality of second measurement points on a vertical bisector of said line segment;
A second phase of the light intensity change at the measurement point is determined. A plurality of third measurement points on a third oblique line passing through the midpoint of the line segment and forming a predetermined angle in the positive direction with respect to the line segment Calculating a third phase of the light intensity change at the third measurement point at a point; a plurality of fourth oblique lines passing through the midpoint of the line segment and forming a predetermined angle in the negative direction with respect to the line segment; The fourth phase of the light intensity change at the fourth measurement point is determined at the fourth measurement point, and the first measurement point position is X, the first phase is Y, and the first phase Y Is approximated by a first function F of a first measurement position X, the second measurement point position is X, the second phase is Y, and the second phase Y is a second measurement position X Approximate by a second function F, X is the third measurement point position, Y is the third phase, and the third phase Y is approximated by a third function F of the third measurement position X. The fourth station position , X is the fourth phase, and the fourth phase Y is approximated by a fourth function F at a fourth measurement position X. The remaining of the first function F and the first phase Y Difference Δ, residual Δ between the second function F and the second phase Y, residual Δ between the third function F and the third phase Y, and the fourth function F and the fourth phase The lens adjusting device according to any one of claims 38 to 50, wherein a higher order aberration of the optical system is evaluated based on a residual Δ from Y. 57. The diffraction grating, wherein 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (8 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: light incident on the diffraction grating from the condenser lens The incident light beam angle) nk: the refractive index of the diffraction grating λ: the wavelength of light is satisfied.
Lens adjustment device. 58. The diffraction grating, wherein 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (4 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: light incident on the diffraction grating from the condenser lens The incident light beam angle) nk: the refractive index of the diffraction grating λ: the wavelength of light is satisfied.
Lens adjustment device. 59. The diffraction grating, wherein 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (4 / λ) ≦ 1.20 0.4 ≦ du ≦ 0.6 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: diffraction grating from condensing lens 58. The incident light beam angle of light incident on the surface of the light source nk: the refractive index of the diffraction grating λ: the wavelength of light is satisfied.
Lens adjustment device. 60. The diffraction grating, wherein 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (2 / λ) ≦ 1.20 0.4 ≦ du ≦ 0.6 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: diffraction grating from condensing lens 58. The incident light beam angle of light incident on the surface of the light source nk: the refractive index of the diffraction grating λ: the wavelength of light is satisfied.
Lens adjustment device. 61. A method for adjusting a condenser lens included in an optical system, comprising: (a) diffracting light transmitted through the condenser lens by a diffraction grating, and sharing interference light of two diffracted lights of different orders. (B) moving the diffraction grating; (c) receiving the sharing interference light with a receiver; and (d) interfering with the sharing interference light received by the receiver. In the image, the phase of the light intensity change is obtained at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the two diffracted lights, and the characteristics of the condenser lens are determined based on the phase. A method of adjusting a lens, comprising: a step of detecting with a detector; and (e) adjusting a position of the condenser lens with an adjusting mechanism based on a detection result of the characteristic detector. 62. A method for adjusting a condenser lens included in an optical system, comprising: (a) diffracting light transmitted through the condenser lens by a diffraction grating, and sharing interference of two diffracted lights of different orders. A step of emitting light; (b) a step of moving the diffraction grating; (c) a step of receiving an image of the sharing interference light with a receiver; and (d) a step of receiving the sharing interference light received by the receiver. In the interference image, the above 2
Obtain the phase of the light intensity change at a plurality of measurement points on a measurement line passing through the midpoint of a line segment connecting the optical axes of the two diffracted lights, and detect the characteristics of the condenser lens with a characteristic detector based on the phases. Process and
(E) receiving the reflected light or transmitted light of the condensing lens by a second image receiving member; and (f) determining the position of the condensing lens based on information on the light received by the second image receiving member. Adjusting the lens with a lens adjusting mechanism. 63. The condensing lens according to claim 62, wherein the converging lens has an edge surface around the lens surface, and the second image receiving member receives reflected light or transmitted light from the edge surface.
3. Lens adjustment method. 64. The method for adjusting a lens according to claim 62, wherein the diffraction grating is a reflection type diffraction grating. 65. The method for adjusting a lens according to claim 62, wherein the diffraction grating is a transmission diffraction grating. 66. The lens adjusting method according to claim 62, wherein the adjusting mechanism includes a mechanism for moving the condenser lens in the optical axis direction. 67. The method according to claim 62, wherein the adjusting mechanism includes a mechanism for moving the condenser lens in a direction orthogonal to the optical axis. 68. The method for adjusting a lens according to claim 62, wherein the adjusting mechanism includes a mechanism for rotating the condenser lens around an optical axis. 69. The method for adjusting a lens according to claim 62, wherein said characteristic detecting device includes a mechanism for moving an image receiving body in an optical axis direction. 70. The apparatus according to claim 62, further comprising a mechanism for moving said diffraction grating in the optical axis direction.
Adjustment method for any of the lenses. 71. The apparatus according to claim 62, further comprising a mechanism for rotating said diffraction grating around an optical axis.
4. The method for adjusting a lens according to any one of 4. 72. A method of adjusting a condenser lens included in an optical system, comprising: (a) converting light emitted from a light source into substantially parallel light and entering the condenser lens; and (b) reflection type diffraction. Using a grating, reflecting and diffracting the light condensed by the condenser lens, and entering the sharing interference light of two diffracted lights of different orders into the condenser lens;
(C) forming an image of the sharing interference light emitted from the condenser lens with an imaging lens; (d) receiving an image of the formed sharing interference light with an image receiving body; and (e). In the sharing interference image received by the image receiver, the phase of the light intensity change is determined at a plurality of measurement points on a measurement line passing through the midpoint of the line segment connecting the optical axes of the two diffracted lights, and the phase is determined based on the phase. Determining a characteristic of the condenser lens with a characteristic detector. 73. A method for adjusting a condenser lens included in an optical system, comprising: (a) a step of causing light emitted from a light source to enter the condenser lens as substantially parallel light; and (b) a transmission diffraction grating. And transmitting and diffracting the light condensed by the condensing lens, and inputting a shared interference light of two diffracted lights of different orders to a second condensing lens,
(C) a step of forming an image of the sharing interference light emitted from the second condenser lens, and (d) a step of receiving the formed sharing interference light by an image receiving body.
(E) In a sharing interference image received by the image receiving body, a phase of a light intensity change is obtained at a plurality of measurement points on a measurement line passing through a midpoint of a line segment connecting the optical axes of the two diffracted lights, Obtaining a characteristic of the condenser lens using a characteristic detector based on the above method. 74. The characteristic detector obtains a phase of a change in light intensity at a plurality of measurement points on a line connecting the optical axes of the diffracted light in the sharing interference image, and determines the position of the measurement point by X. The phase is set to Y, the phase Y is approximated by a linear function of a measurement position X, and the defocus amount of the optical system is evaluated by a linear coefficient value of the linear function. A method for adjusting a lens according to any of 58 to 70. 75. The characteristic detector, wherein in the shearing interference image, a predetermined angle passes through a midpoint of a line segment connecting the optical axes of the diffracted light and has a predetermined angle in a positive direction and a negative direction with respect to the line segment. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on the two oblique lines, and the measurement point position is X, the phase is Y, and the phase Y is the measurement position X for each of the two oblique lines. 71. The adjustment of the lens according to any one of claims 58 to 70, wherein approximation is made with a quadratic function or a cubic function, and coma aberration is evaluated using a quadratic coefficient value of the quadratic function or cubic function. Method. 76. The characteristic detector, wherein in the shearing interference image, a perpendicular bisector passing through a midpoint of a line connecting the optical axes of the diffracted light, and positive and negative directions with respect to the line segment. The phase of the light intensity change at the measurement point is determined by a plurality of measurements on two oblique lines forming a predetermined angle, and the measurement point position is X, the phase is Y, and the phase is A quadratic or cubic coefficient value of the quadratic function or cubic function obtained by approximating Y with a quadratic or cubic function of the measurement position X; And evaluating the coma aberration using a difference between the phase Y and a quadratic function value of the quadratic function or the cubic function obtained by approximating the phase Y with a quadratic function or a cubic function of the measurement position X. A method for adjusting a lens according to any one of claims 58 to 70. 77. The predetermined angle is from 30 ° to 60 °.
The method for adjusting a lens according to claim 77, wherein the lens has a range. 78. The characteristic detector obtains a phase of a light intensity change at a plurality of measurement points on a vertical bisector of a line connecting the optical axes of the diffracted light in the sharing interference image. The measurement point position is X and the phase is Y, and the phase Y is approximated by a linear function of the measurement position X, and the astigmatism of the optical system is evaluated by a linear coefficient value of the linear function. 75. The method for adjusting a lens according to claim 62, wherein: 79. The characteristic detector obtains a phase of a change in light intensity at a plurality of measurement points on a line segment passing through the optical axis of the diffracted light in the sharing interference image, The position is X, the phase is Y, the phase Y is approximated by a cubic function or a quartic function of the measurement position X, and the spherical aberration of the optical system is evaluated by a cubic coefficient value of the cubic function or quartic function. 75. The method for adjusting a lens according to claim 62, wherein: 80. The characteristic detector includes: in the shearing interference image: at a plurality of first measurement points on a line connecting the optical axes of the two diffracted lights, the light intensity at the first measurement point; Determining a first phase of the change; a second phase at a plurality of second measurement points on a vertical bisector of said line segment;
A second phase of the light intensity change at the measurement point is determined. A plurality of third measurement points on a third oblique line passing through the midpoint of the line segment and forming a predetermined angle in the positive direction with respect to the line segment Calculating a third phase of the light intensity change at the third measurement point at a point; a plurality of fourth oblique lines passing through the midpoint of the line segment and forming a predetermined angle in the negative direction with respect to the line segment; The fourth phase of the light intensity change at the fourth measurement point is determined at the fourth measurement point, and the first measurement point position is X, the first phase is Y, and the first phase Y Is approximated by a first function F of a first measurement position X, the second measurement point position is X, the second phase is Y, and the second phase Y is a second measurement position X Approximate by a second function F, X is the third measurement point position, Y is the third phase, and the third phase Y is approximated by a third function F of the third measurement position X. The fourth station position , X is the fourth phase, and the fourth phase Y is approximated by a fourth function F at a fourth measurement position X. The remaining of the first function F and the first phase Y Difference Δ, residual Δ between the second function F and the second phase Y, residual Δ between the third function F and the third phase Y, and the fourth function F and the fourth phase 75. The method for adjusting a lens according to any one of claims 62 to 74, wherein a higher-order aberration of the optical system is evaluated based on a residual Δ from Y. 81. The diffraction grating, wherein 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (8 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: light incident on the diffraction grating from the condenser lens 82. The incident light beam angle) nk: the refractive index of the diffraction grating λ: the wavelength of light is satisfied.
How to adjust the lens. 82. The diffraction grating, wherein 0.8 ≦ Pk · (A / λ) ≦ 1.2 0.5 ≦ dk · (nk−1) · (4 / λ) ≦ 2 0.2 ≦ du ≦ 0.8 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: light incident on the diffraction grating from the condenser lens 82. The incident light beam angle) nk: the refractive index of the diffraction grating λ: the wavelength of light is satisfied.
How to adjust the lens. 83. The diffraction grating, wherein 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (4 / λ) ≦ 1.20 0.4 ≦ du ≦ 0.6 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: diffraction grating from condensing lens 82. An incident light beam angle of light incident on the optical fiber, nk: a refractive index of a diffraction grating, λ: a wavelength of light, and the following condition is satisfied.
How to adjust the lens. 84. The diffraction grating, wherein 0.8 ≦ Pk · sin (θs / 2) /λ≦1.2 0.8 ≦ dk · (nk−1) · (2 / λ) ≦ 1.20 0.4 ≦ du ≦ 0.6 Pk: grating pitch dk: grating depth du: grating duty ratio (= width of grating groove / grating pitch) A: numerical aperture of diffraction grating (= sin θs θs: diffraction grating from condensing lens 82. An incident light beam angle of light incident on the optical fiber, nk: a refractive index of a diffraction grating, λ: a wavelength of light, and the following condition is satisfied.
How to adjust the lens.