JP3146590B2 - Shape measuring method and shape measuring system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a system for measuring a shape of an optical lens or the like.

[0002]

2. Description of the Related Art When an optical surface shape error is measured by an interferometer, a relative measurement with a reference surface is generally performed. The surface accuracy (referred to as PV) of the reference surface is PV = λ / 1.
0 to λ / 20 (for example, λ = 633 nm in the case of a He-Ne laser often used for an interferometer),
In order to perform a measurement with higher accuracy than that, it is necessary to measure an absolute shape.

[0003] As a conventional measuring method of this kind, there is the following method.

One method is shown in FIGS. This shape measuring system for determining the surface shape of a lens to be measured M2, which is a first object to be measured, comprises a laser light source 1;
It has an image sensor 2, a semi-transparent mirror 3, and collimating lenses (Fizeo lenses) L and M1. Then, the wavefront reflected by the test lens M2 and the reference wavefront by the collimating lens M1 interfere with each other, and the shape error of the test lens M2 is measured based on the interference fringe pattern. The measurement is performed according to the following procedure.

[0005] For simplicity of description, Front
The optics aberration is assumed to be zero.

(1) Measurement is performed in the state shown in FIG. At this time, the rotational positions of the collimating lenses (Fizeo lenses) L and M1 and the test lens M2 are set to 0 °. The shape error measured at this time is F0 (shape error of collimating lens M1 at 0 °) + H0 (0
(Shape error of the test lens M2 in °).

(2) Measurement is performed in the state shown in FIG. 2B (only the lens to be tested is rotated by 180 ° around the optical axis). At this time, the rotational positions of the collimating lenses L and M1 are 0 °. The shape error measured at this time is
F0 (shape error of collimating lens M1 at 0 °) + H180 (shape error of test lens M2 at 180 °). This data is calculated by 180 °
By rotating, F180 (the shape error of the collimating lens M1 at 180 °) + H0 (the shape error of the test lens M2 at 0 °) is obtained.

(3) The measurement is performed in the state shown in FIG. 3 (the lens M2 is removed and the mirror-4 is placed at the focal position of the collimating lenses L and M1). At this time, the rotational positions of the collimating lenses L and M1 are 0 °. The shape error measured at this time is only the shape error of the collimating lens M1, and F0 (shape error of the collimating lens M1 at 0 °) + F180 (180
(Shape error of the collimating lens M1 in °).

(4) By calculating the difference between the data of (1) and (2), F0 (the shape error of the collimating lens M1 at 0 °) −F180 (the error of the collimating lens M1 at 180 °) Shape error). By adding this result and the data of (3), F0 is obtained. By subtracting this F0 from the result of (1), H0 (shape error of the test lens M2 at 0 °) is obtained.

The problem with this method is that the lens to be inspected can be precisely adjusted while maintaining the alignment of the entire system accurately.
That is, it must be turned 80 ° and a mirror must be installed.

Another method for determining the shape error of the collimating lens is the "wavefront averaging method". In this measurement method, a wavefront measurement is performed a plurality of times while displacing the measurement area without changing the collimating lens 41 while using the lens 42 having a bright F number. By averaging the measurement data, it is possible to reduce the influence of the shape error of the test lens 42 on the measurement and obtain the surface shape of the collimating lens 41. This method assumes that the shape error of the test lens 42 is random. FIG. 4 is a diagram illustrating the principle of this measurement method. Equation 1 is obtained by averaging the measurement data WK.

[0012]

(Equation 1)

When the number of measurements n is increased while changing the surface shape WTK of the lens 42 to be inspected, the second term on the right side of the equation 1 approaches zero, so the surface shape WR of the collimating lens 41 is obtained.

This method uses a collimating lens 41.
By preparing a test lens 42 having a larger NA than that of the above, and shifting the test lens 42 laterally with respect to the optical axis, the wavefront is averaged, and the shape error of the reference spherical surface of the collimating lens 41 is reduced. I was asking.

[0015]

In the above-mentioned prior art, there is a problem that the shape of the object to be measured is limited.

Further, non-uniformity of data to be averaged is always required.

An object of the present invention is to use a wavefront averaging for generating a constant pattern and extract the pattern (wavefront generation extraction method), thereby alleviating the restriction on the averaging of the lens to be measured. To provide a law and system.

[0018]

SUMMARY OF THE INVENTION The present invention relates to a method for measuring an object to be measured.
These reflected wavefronts interfere with the reference wavefront by the reference plane,
Due to the interference fringe pattern, the shape error of the measurement object
A shape measurement method for obtaining a measurement object, the rotational axis
Determining the rotational average shape related to , from the measurement object
Interference between the reflected wavefront of the
Finding the interference fringe pattern, the rotational average shape,
From the interference fringe pattern, the shape error of the measurement object
Characterized by determining a non-rotationally symmetric component.
You.

[0019]

According to the present invention, a shape error of a first object to be measured is obtained from a true rotationally symmetric component (RS) and a non-rotationally symmetric component (AS) defined below. The definition of the true rotationally symmetric component (RS) and the non-rotationally symmetric component (AS) will be described with reference to the schematic diagram of FIG. In FIG. 5, H is the first value to be obtained.
3 shows a distribution diagram of the shape error of the object to be measured. While rotating the first measurement object, measurement values at each point on the first measurement object are obtained, and the average of the measured values is a rotationally symmetric component indicated by RS. The non-rotationally symmetric component denoted by AS is HR
Defined by S.

The procedure for obtaining the shape error H is as follows.

(1) Obtain an interference fringe pattern OR. This is the sum of the shape error F0 of the collimating lens, the true rotationally symmetric component RS, and the non-rotationally symmetric component AS.

(2) The first rotationally symmetric component detecting means obtains a first rotationally symmetric component by averaging the surface shape data obtained by measuring while rotating the rotating means. This is the sum of the shape error F0 of the collimating lens and the rotationally symmetric component (referred to as RS1).

(3) The first rotating shaft is displaced by the displacement means. The second rotationally symmetric component detecting means is configured to rotate the first measurement object or the second measurement object about at least one rotation about the displaced first rotation axis, and obtain the surface shape data obtained by the measurement. The second rotationally symmetric component is obtained by averaging the data. This is the sum of the shape error F0 of the collimating lens and the rotationally symmetric component (referred to as RS2).

(4) The true rotationally symmetric component detecting means includes:
From the rotationally symmetric component and the second rotationally symmetric component, a rotationally symmetric component that does not include a shape error of the collimating lens (this is called a true rotationally symmetric component, which is RS1 or RS1)
2) for the first rotationally symmetric component or the second rotationally symmetric component.

(5) The shape error detecting means includes (2),
The shape error of the collimating lens is obtained from the true rotational symmetric component obtained in (3) and at least one of the first rotational symmetric component and the second rotational symmetric component.

(6) The first calculating means obtains a difference between the interference fringe pattern obtained in (1) and the shape error of the collimating lens obtained in (5), and The true surface shape H is calculated.

[0027]

FIG. 6 shows a Fizeau-type interferometer system which is a shape measuring system according to the present invention. This Fizeau-type interferometer system comprises a control unit 8, a processing unit 15, a laser light source 1, an image pickup device 2, a semi-transparent mirror 3, collimating lenses (Fizeo lenses) L and M1, X stage for positioning the test lens 10 to be measured in three axial directions
It has a stage 4, a Y stage 5, a Z stage 6, a bearing 14 as rotating means, and an α stage 7 as moving means. The control unit 8 controls the image pickup device 2 and the laser light source 1,
And exchange data with the processing unit 15. As shown in FIG. 1, the processing unit 15 includes a first rotationally symmetric component detecting unit 81, a second rotationally symmetric component detecting unit 82, a true rotationally symmetric component detecting unit 83, and a shape error detecting unit 84.
And a first calculating means 85 and an interference fringe pattern stored in a memory 86. The processing unit 15 has a memory 86 for storing programs and data, a CPU, and a CPU (not shown).

The CPU and the memory 86 include a first rotationally symmetric component detecting means 81, a second rotationally symmetric component detecting means 82, a true rotationally symmetric component detecting means 83, and a shape error detecting means shown in FIG. The functions of the means 84 and the first calculating means 85 are executed.

The bearing 14, which is a rotating means, rotates the test lens 10 around the optical axis. The α stage 7 serving as a moving unit rotates the optical axis of the lens 10 to be measured around the rotation center 9.

Then, the reflected wavefront of the lens 10 to be measured and the reference wavefront of the collimating lens M1 are caused to interfere with each other, and the shape error of the lens 10 is measured based on the interference fringe pattern. .

In the above configuration, the light emitted from the laser 1 enters the semi-transparent mirror 3. A part of this light is reflected by the reference surface 16 of the Fizeau lenses L and M1, returns to the semi-transparent mirror 3, and goes straight upward. Thus, the light enters the image sensor 2.

On the other hand, a part of the light incident on the Fizeo lenses L and M1 is converted into an appropriate spherical wave by the Fizeo lenses L and M1 and is incident on the lens 10 to be measured. And
Here, the light is reflected again and passes through the Fizeau lenses L and M1,
After returning to the semi-transparent mirror 3, it is bent upward and enters the image sensor 2.

At this time, if the position of the test lens 10 is adjusted and the shape of the test lens 10 and the shape of the spherical waves generated by the Fizeo lenses L and M1 substantially match, the image pickup element 2 is displayed. Interference fringes of sufficient roughness are observed. The observed interference fringe gives information on the deviation between the shape of the lens 10 to be measured and the shape of the spherical wave, that is, information on the wavefront aberration, and one fringe is exactly equal to the deviation of half the wavelength λ of the light from the laser light source 1. Has become.

[0034] Therefore, if the shape of the lens 10 is close to the spherical surface, subject by analyzing the interference fringe pattern roughness of the interference fringes become as appropriate over the entire lens 1
0 can be measured at once.

The measurement is performed according to the following procedure.

(1) An interference fringe pattern OR is obtained in a state where the optical axes of the collimating lenses L and M1 and the central axis (first rotation axis) of the lens 10 to be measured coincide with each other. This is the sum of the shape error F0 of the collimating lenses L and M1, the rotationally symmetric component RS1, and the non-rotationally symmetric component AS.

(2) Next, the surface shape data shown in FIG. The first rotationally symmetric component detecting means 81 obtains a first rotationally symmetric component by averaging the surface shape data obtained by measurement while rotating the bearing 14.
This is the sum of the shape error F0 of the collimating lens M1 and the rotationally symmetric component RS1.

(3) The central axis of the lens 10 is moved by the α stage 7 for moving the central axis of the lens 10 to be examined. At the same time, the X stage 4, the Y stage 5, and the Z stage 6 allow the center of curvature of the test surface of the test lens 10 to coincide with the focal position of the collimating lenses L and M1. Also move. The second rotationally symmetric component detecting means 82 averages the surface shape data obtained by the measurement while rotating the test lens 10 about the center axis after the movement, and obtains the second rotationally symmetric component. Ask for. This is because the shape error F0 of the collimating lens M1 and the rotationally symmetric component (RS
2). Collimating lenses L, M
Since the optical axis 1 and the central axis of the test lens 10 are shifted, the interference fringe is measured only at the portion shown in FIG.

(4) The true rotationally symmetric component detecting means 83
From the first rotationally symmetric component and the second rotationally symmetric component, a rotationally symmetric component that does not include a shape error of the collimating lens M1 (this is called a true rotationally symmetric component, RS1 or RS1)
2) for the first rotationally symmetric component. This will be described with reference to FIG. Since the rotationally symmetric component on each ring shown in FIGS. 7 and 8 has the same value, as shown in FIG. 9, the rotationally symmetric component is RS1A + F0 (the collimating lens M
1), RS1B + F0, RS2A + F0, R
S2B + F0. When the difference between the first rotationally symmetric component and the second rotationally symmetric component is calculated, the shape error of the collimating lens M1 disappears, and the values of the intersections A, B, C, and D become the values shown in FIG.
It becomes as shown in. On the basis of the value of the second rotationally symmetric component at the center O, since the value on the arc OE includes a common part of a constant RS2A, all the values of the first rotationally symmetric component are determined.

Further, by utilizing the fact that the values of the first rotationally symmetric components are the same, the point B and the point C can be obtained by using the values on the arcs OB and CF instead of the arc OE. The value of the rotationally symmetric component is obtained.

Further, as another method for obtaining the unknown value, RS
1A, RS1B, RS2A, RS2B, and RS3B, RS2A, R based on RS1A, utilizing the fact that there are substantially 3 equations for A, B, C, D values.
The value of S2B can also be determined.

Thus, the rotationally symmetric component of the shape error is determined. This operation may be performed for the entire test lens 10.

(5) The shape error detecting means 84 calculates the shape error of the collimating lens M1 from the first rotationally symmetric component and the true rotationally symmetric component obtained in (2).

(6) The first calculating means 85 calculates the difference between the interference fringe pattern determined in (1) and the shape error of the collimating lens M1 determined in (5), and calculates the trueness of the lens to be measured. Is calculated.

Next, as a second embodiment, a method for directly calculating the true surface shape H of the lens to be inspected without finding the shape error of the collimating lens M1 will be described.

The Fizeau-type interferometer system includes a control unit 8
7, a laser light source 1, an imaging device 2, a semi-transparent mirror 3, collimating lenses (Fizeo lenses) L and M1,
X stage for positioning the test lens 10 in three axial directions
It has a stage 4, a Y stage 5, a Z stage 6, a bearing 14 as rotating means, and an α stage 7 as moving means. That is, instead of the processing unit 15 in FIG.
7 is provided. As shown in FIG. 1, the control unit 87 includes a first rotationally symmetric component detecting unit 81, a second rotationally symmetric component detecting unit 82, and a true rotationally symmetric component detecting unit 83.
And second calculation means 88 and non-rotationally symmetric component detection means 8
9 and an interference fringe pattern stored in the memory 86.

The bearing 14, which is a rotating means, rotates the test lens 10 around the optical axis. The α stage 7 serving as a moving unit rotates the optical axis of the lens 10 to be measured around the rotation center 9.

The reflected wavefront of the lens 10 to be measured and the reference wavefront of the collimating lens M1 are caused to interfere with each other, and the shape error of the lens 10 is measured based on the interference fringe pattern. .

The measurement is performed in the following procedure.

(1) An interference fringe pattern OR is obtained in a state where the optical axes of the collimating lenses L and M1 and the center axis of the lens 10 to be measured coincide with each other. This is the sum of the shape error F0 of the collimating lenses L and M1, the rotationally symmetric component RS1, and the non-rotationally symmetric component AS.

(2) Next, the surface shape data shown in FIG. 7 is obtained while the test lens 10 is rotated once by the bearing 14. The first rotationally symmetric component detecting means 81 obtains a first rotationally symmetric component by averaging the surface shape data obtained by measurement while rotating the bearing 14.
This is because of the shape error F of the collimating lenses L and M1.
It is the sum of 0 and the rotationally symmetric component RS1.

(3) The central axis of the lens 10 is moved by the α stage 7 for moving the central axis of the lens 10 to be examined. At the same time, the X stage 4, the Y stage 5, and the Z stage 6 allow the center of curvature of the test surface of the test lens 10 to coincide with the focal position of the collimating lenses L and M1. Also move. The second rotationally symmetric component detecting means 82 averages the surface shape data obtained by the measurement while rotating the test lens 10 at least one rotation around the central axis after the movement, and obtains the second rotationally symmetric component. Find the components. this is,
This is the sum of the shape error F0 of the collimating lens M1 and the rotationally symmetric component RS2. Collimating lenses L, M
Since the optical axis 1 and the optical center axis of the test lens 10 are shifted, the interference fringe is measured only at the portion shown in FIG.

(4) The true rotationally symmetric component detecting means 83
From the first rotationally symmetric component and the second rotationally symmetric component, a rotationally symmetric component that does not include a shape error of the collimating lens M1 (this is called a true rotationally symmetric component, RS1 or RS1)
2) for the first rotationally symmetric component. This will be described with reference to FIG. Since the rotationally symmetric components on each ring shown in FIGS. 7 and 8 have the same value, they are referred to as RS1A, RS1B, RS2A, and RS2B as shown in FIG. When the difference between the first rotationally symmetric component and the second rotationally symmetric component is calculated, the shape error of the collimating lens M1 disappears, and the values of the intersections A, B, and C become as shown in FIG.
When the value of RS2A is determined as a reference value of the shape error of the lens to be measured, the rotationally symmetric component of the shape error is determined in the order of C, B, and A. This operation may be sequentially performed on the entire test lens 10.

(5) The non-rotationally symmetric component detecting means 89 outputs the interference fringe pattern (F0, RS1,
AS) and a first rotationally symmetric component (F0, RS
(A sum of 1) is obtained.

(6) The second calculation means 88 calculates the sum of the true rotationally symmetric component RS obtained in (4) and the non-rotationally symmetric component AS obtained in (5), and calculates the true value of the lens to be measured. Surface shape H
Is calculated. As described above, it is possible to provide a Fizeau-type interferometer system capable of measuring a test lens smaller than the NA of the collimating lens. In addition, in the case of FIGS. 2 and 3 of the related art, three points (0 °, 180 °,
(Mirror setting) only, the alignment requirement is severe, but in the case of the present invention, since 360 ° is divided into a large number, even if the alignment requirement at each position is relaxed, the final The effect is that the accuracy is improved over the prior art.

According to this measuring method, there is an advantage that even if a hole is formed in the center of the lens to be inspected, it is not affected at all.

In the above description, the rotation of the θ stage is performed by dividing 360 ° in accordance with the roughness of the shape error of the lens to be inspected. However, when the shape error becomes large, the division must be made finer. Must. Therefore, when the shape error is large, divide and stop repeating the measurement,
During one rotation of the θ stage, data may be accumulated in the CCD. This is to integrate the data with time, and then an average may be taken.

FIGS. 7, 8, and 9 show that the lateral shift amount is the same as the radius, and for simplicity of calculation, the data is limited to the data on the arc OE.
An example in which the shape error is obtained is shown below.
Not only the data on E but also all the data of the union part in FIG.

On the other hand, when the calculation is performed by a method of sequentially connecting, the amount of lateral shift can be made smaller than the radius.

Further, in order to reduce the measurement error (the position of the test lens may be shifted if the lateral shift is increased due to the method of holding the test lens, an error caused by this may be reduced). If it is desired to reduce the size, for example, the measurement may be performed by dividing the measurement to the left and right by a half shift in FIG. Although the number of horizontal shifts is doubled, the same data as in FIG. 7 is obtained, and the above error is reduced, so that higher accuracy can be expected.

Although the present embodiment has been described for the case where there is one rotating shaft, the present invention is not limited to this, and can be similarly applied to the case where there are two rotating shafts. This will be described with reference to FIG.

The present Fizeau-type interferometer system has a control unit 8
Laser light source 1, imaging element 2, semi-transparent mirror 3, collimating lenses (Fizeo lenses) L and M1, and first rotating means (first rotating means) for rotating lens 1110 to be inspected. Shaft 120) and an α stage 117 as a second rotating means (having a second rotating shaft 1173). The control unit 8 controls the image sensor 2 and the laser light source 1 and exchanges data with the processing unit 1115.

The first rotating means 1120 is connected to the lens 1 to be inspected.
110 is rotated about a rotation axis perpendicular to the optical axis.

Then, the reflected wavefront of the lens 1110 to be measured and the reference wavefront of the collimating lens M1 to be measured are caused to interfere with each other.
This is for measuring the shape error of the test lens 1110.

The measurement is performed according to the following procedure.

(1) The optical axes of the collimating lenses L and M1 coincide with the central axis of the lens 1110 to be measured. In this state, the lens 1 to be inspected is
The surface shape data is taken in a ring shape while rotating 110 one rotation. Surface shape data obtained by measuring while rotating
The first rotationally symmetric component is obtained by averaging the data. this is,
This is the sum of the shape error F0 of the collimating lens M1 and the rotationally symmetric component RS1.

(2) At least one test lens 1110 is rotated around the second rotation axis 1173 by the α stage 117.
While rotating, take the surface shape data. The second rotationally symmetric component is obtained by averaging the surface shape data obtained by the measurement. This is the sum of the shape error F0 of the collimating lens M1 and the rotationally symmetric component RS2.

(3) From the first rotationally symmetric component and the second rotationally symmetric component, a rotationally symmetric component that does not include a shape error of the collimating lens M1 (this is called a true rotationally symmetric component, which is RS1 Or RS2) for the first rotationally symmetric component.

In this way, the rotationally symmetric component of the shape error is determined. This operation may be performed for the entire test lens 1110.

(4) From the first rotationally symmetric component and the true rotationally symmetric component obtained in (1), the collimating lens M1
Is obtained.

As described above, according to the present invention, since the randomness of the data to be averaged is not required, there is no limit on the magnitude relationship between the NA of the collimating lens and the NA of the lens to be inspected. Even if it is the same as the NA of the lens,
Alternatively, it is possible to provide a shape measurement system capable of measuring a measurement object having an NA in any case of small or large.

In this embodiment, the case where the first and second rotationally symmetric components are determined by using one object to be measured has been described. However, the present invention is not limited to this. The same applies to the case where the second rotationally symmetric component is obtained by using two measurement objects (a first measurement object and a second measurement object).

When the second rotationally symmetric component is determined using only the first object to be measured, it is not always necessary to simultaneously displace the first rotation axis and the first object to be measured. This is shown in FIG. The test lens 121 is
After the first rotational symmetric component is obtained for the first rotation axis 122 without displacement, the first rotation axis 123 after the displacement is obtained.
May be used to obtain a second rotationally symmetric component. Instead of using the first rotation axis 123 after the displacement, a second rotation axis may be prepared, and a second rotational symmetric component may be obtained for the second rotation axis.
Further, as shown in FIG. 12, the first rotation axis and the second rotation axis do not necessarily need to pass through the center of the outer shape of the lens 121 to be measured.

Further, although the present embodiment has described the Fizeau-type interferometer system, the present invention is not limited to this, and the present invention is not limited to this. The same can be applied to a mangling interferometer. In the case of a Michelson interferometer and a Twyman-Green interferometer, for a spherical surface, the same operation as in this embodiment may be performed. In the case of a plane, an axis perpendicular to the plane may be used as the first rotation axis. Then, the second rotationally symmetric component may be obtained by moving this in parallel.

In the above embodiment, by rotating
Although a shape is required, the present invention is not limited to this, and it can be determined by swinging instead of rotation.

[0076]

As described above, according to the present invention, since non-uniformity of data to be averaged is not required, it is possible to measure an object to be measured having the same NA as that of the collimating lens. A possible shape measurement system can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control unit according to the present invention.

FIG. 2 is an explanatory diagram of a sphericity measurement method according to the related art.

FIG. 3 is an explanatory diagram of a sphericity measurement method according to the related art.

FIG. 4 is an explanatory diagram of a sphericity measurement method according to the related art.

FIG. 5 is a principle diagram of a sphericity measuring method according to the present invention.

FIG. 6 is a block diagram of a Fizeau-type interferometer system according to the present invention.

FIG. 7 is an explanatory diagram of a sphericity measurement method according to the present invention.

FIG. 8 is an explanatory diagram of a sphericity measurement method according to the present invention.

FIG. 9 is an explanatory diagram of a sphericity measurement method according to the present invention.

FIG. 10 is a block diagram of a control unit according to the present invention.

FIG. 11 is a block diagram of a Fizeau interferometer system according to the present invention.

FIG. 12 is a block diagram of a Fizeau-type interferometer system according to the present invention.

[Explanation of symbols]

Reference numeral 8 denotes a control unit, 1 denotes a laser light source, 2 denotes an image sensor, 3 denotes a semi-transparent mirror, L and M1 denotes a collimating lens (Fizeo lens), 10 denotes a test lens, 4 denotes an X stage, and 5 denotes an X stage. ... Y stage, 6 ... Z stage, 14 ... bearing, 7 ... α stage, 81 ... first rotationally symmetric component detecting means, 82 ... second
83: true rotationally symmetric component detecting means, 84: shape error detecting means, 85: first calculating means.

────────────────────────────────────────────────── (5) References JP-A-5-223542 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01B 9/00-11/30 102 G01M 11 / 00-11/08

Claims (14)

(57) [Claims] And reflected wavefront from 1. A measurement object, to interfere with a reference wavefront by the reference plane, by the interference fringe pattern,
A shape measurement method for obtaining a shape error of the measurement object, wherein a rotation average shape of a measurement object with respect to a rotation axis is obtained, and a reflected wavefront from the measurement object and a reference wavefront caused by a reference surface interfere with each other. was to determine the interference fringe pattern, said rotary average shape, more to the interference fringe pattern, wherein
A shape measuring method characterized by determining a non-rotationally symmetric component of a shape error of a measuring object . 2. A shape measuring method for causing a reflected wavefront from a first measurement object to interfere with a reference wavefront by a reference surface and obtaining a shape error of the first measurement object from the interference fringe pattern. Determining a first rotational average shape of the first measurement object with respect to a first rotation axis; interference caused by interference between a reflected wavefront from the first measurement object and a reference wavefront by a reference surface. determining the fringe pattern, said first rotation mean shape, Ri the interference fringe pattern I <br/>, obtaining a non-rotationally symmetric element of the shape error of the first measurement object, the first Calculating a second rotational average shape of the second rotational axis with respect to the second rotational axis, either of the measurement object or the second measurement object, from the first rotational average shape and the second rotational average shape, A rotationally symmetric component is calculated for the first rotational average shape. Melco and shape measuring method in which the more the non-rotationally symmetric element and the rotationally symmetric element, characterized in that consists in calculating the shape error of the first measurement object. 3. A shape measuring method in which a reflected wavefront from a first measurement object and a reference wavefront by a reference surface interfere with each other, and a shape error of the first measurement object is determined by an interference fringe pattern. Obtaining a first rotation average shape of the first measurement object with respect to the first rotation axis; a second rotation axis of either the first measurement object or the second measurement object. Determining a second rotational average shape for the first rotational average shape or the second rotational average shape from the first rotational average shape and the second rotational average shape. It determined that, with the rotationally symmetrical component, comprising either one of said first rotation mean shape and before <br/> Symbol second rotation mean shape, before
Determining the shape error of the reference plane from the one used for determining the rotationally symmetric component; interference fringes that cause the reflected wavefront from the first measurement object to interfere with the reference wavefront due to the reference plane. A shape measuring method comprising calculating a shape error of the first measurement object from a pattern and a shape error of the reference plane. 4. The shape measuring method according to claim 1, wherein the measuring object has a spherical surface to be measured, and the rotation axis passes through a center of curvature of the spherical surface. A shape measuring method characterized in that: 5. The shape measuring method according to claim 1, wherein the measuring object has a plane to be measured, and the rotation axis is perpendicular to the plane. A shape measuring method characterized by the following. 6. The shape measuring method according to any one of claims 1 to 5, wherein, when obtaining a rotation average shape with respect to the rotation axis, the measurement object is rotated at least once around the rotation axis. And measuring the surface shape data corresponding to a plurality of rotation positions, and averaging the surface shape data measured corresponding to the plurality of rotation positions to obtain the rotation average shape. 7. The shape measuring method according to claim 2, wherein, when obtaining the rotationally symmetric component, a property of a concentric contour line included in the rotationally symmetric component is obtained by:
An area in which the first rotational average shape is obtained;
A shape measurement method characterized by using the rotation average shape in a region where the rotation average shape is obtained. 8. The shape measuring method according to claim 7, wherein, when obtaining the rotationally symmetric component, all data of the contour lines in the overlapping area are used. 9. A wavefront reflected from an object to be measured and a reference wavefront caused by a reference plane interfere with each other.
A shape measurement system for determining a shape error of the measurement object, a unit for determining a rotation average shape of the measurement object with respect to a rotation axis, interference between a reflected wavefront from the measurement object and a reference wavefront by a reference surface. means for determining an interference fringe pattern obtained by the a rotation average shape, more to the interference fringe pattern, wherein
Means for calculating a non-rotationally symmetric component of the shape error of the measurement object . 10. A shape measuring system for causing a reflected wavefront from a first measurement object to interfere with a reference wavefront by a reference surface, and obtaining a shape error of the first measurement object based on the interference fringe pattern. Means for obtaining a first rotation average shape of the first measurement object with respect to the first rotation axis; and causing a reflected wavefront from the first measurement object to interfere with a reference wavefront by a reference surface. Means for determining interference fringe patterns
Means for obtaining a non-rotationally symmetric component of the shape error of the first measurement object , based on the first rotation average shape and the interference fringe pattern; Means for determining a second rotation average shape of the object or the second measurement object with respect to a second rotation axis; and a rotational symmetry based on the first rotation average shape and the second rotation average shape. Means for obtaining a component for the first rotational average shape; and means for calculating a shape error of the first measurement object from the non-rotationally symmetric component and the rotationally symmetric component. Shape measurement system. 11. A shape measuring system for causing a reflected wavefront from a first measurement object to interfere with a reference wavefront by a reference surface and obtaining a shape error of the first measurement object from the interference fringe pattern. Means for determining a first rotation average shape of the first measurement object with respect to the first rotation axis; and a second rotation of either the first measurement object or the second measurement object. Means for obtaining a second rotational average shape about an axis; and a rotationally symmetric component, based on the first rotational average shape and the second rotational average shape, the first rotational average shape or the second rotational average. means for determining the shape, and the rotationally symmetric element, comprising either one of said first rotation mean shape and before <br/> Symbol second rotation mean shape, before
Means for determining the shape error of the reference plane, from the one used for determining the rotationally symmetric component, and interference caused by interference between a reflected wavefront from the first measurement object and a reference wavefront by the reference plane. Means for calculating a shape error of the first measurement object from a stripe pattern and a shape error of the reference plane. 12. A memory storing a program for determining an error in the surface shape of a measurement object by an information processing device, the processing for obtaining a rotation average shape of the measurement object with respect to a rotation axis; more and reflected wavefront from the object, the process of obtaining the interference fringe pattern obtained by interference with a reference wave front by the reference plane, and the rotation average shape, and the interference fringes, the measurement object
Memory storing a program, characterized in that is for executing a process of obtaining a non-rotationally symmetric element, the by the information processing apparatus among the objects. 13. A memory in which a program for obtaining an error in the surface shape of a measurement object by an information processing device is stored, wherein a first rotation average of the first measurement object with respect to a first rotation axis is provided. A process of obtaining a shape; and a process of obtaining an interference fringe pattern in which a reflected wavefront from the first measurement object interferes with a reference wavefront by a reference surface.
When, with the first rotation averaged shape, more and the interference fringes, the first
A process of obtaining a non-rotationally symmetric component of the shape error of the first measurement object; and a second rotation average shape with respect to a second rotation axis of either the first measurement object or the second measurement object. Calculating a rotationally symmetric component for the first rotational average shape from the first rotational average shape and the second rotational average shape; and calculating the non-rotational symmetric component and the rotational symmetric component. And a process for calculating a shape error of the first measurement object, and a process for executing the process by the information processing device. 14. A memory storing a program for determining an error in the surface shape of a measurement object by an information processing device, wherein the first rotation average of the first measurement object with respect to a first rotation axis is provided. Processing for obtaining a shape; processing for obtaining a second rotational average shape for a second rotation axis of either the first measurement object or the second measurement object; than the second rotation mean shape, the rotational symmetry component, and process for obtaining the first rotation averaged shape or the second rotation averaged shape, and the rotationally symmetric element, the first rotation mean shape and before < any one of the second rotational average shapes ,
A process of obtaining a shape error of the reference plane from a method used for obtaining the rotationally symmetric component ; and an interference in which a reflected wavefront from the first measurement object interferes with a reference wavefront by the reference surface. A process of calculating a shape error of the first measurement object from the stripe pattern and a shape error of the reference surface, and a process of executing the process by the information processing device. Memory.