JPH08233506A - Method and apparatus for measuring aspherical shape and method for evaluating aspherical surface - Google Patents

Abstract

PURPOSE: To make it possible to measure the cross-sectional shape of the entier body accurately by connecting the shape data in a plurality of scanning regions obtained by a shape reading means with each other, and synthesizing the data into a cross-sectional shape of the entire body. CONSTITUTION: A mark M is formed at the aspherical surface part of an object to be inspected. The aspherical surface of a lens O is divided into two scanning regions A and B, wherein the neighboring parts of the mark M are overlapped. The lens O is set on a gonio-stage and rotated around an axis, which orthogonaly intersects the scanning direction. When a slant angle is imparted and the shapes of the scanning ranges A and B are read, two shape data DA and DB are obtained in correspondence with the shapes of the scanning ranges A and B. In a control/operation device, which is a data processing means, these two shape data DA and DB uodergo data processing in accordance with a program, and the data are connected with the mark part as the common reference. Thus, the cross-sectional shape of the entire body is synthesized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aspherical surface shape measuring method and apparatus / aspherical surface evaluating method.

[0002]

2. Description of the Related Art In order to improve the performance of optical systems, aspherical surfaces are used as the shapes of lens surfaces and reflecting surfaces.

"Aspherical surface" means a radius of curvature of a standard spherical surface: R, a conic constant: K, an aspherical surface coefficient: A, B, C,
D ,. ． And the like, using Cartesian coordinates: X, Z: Z = (1 / R) X ² / [1 + √ {1- (K + 1) (X /
R) ² }] + A ・ X ⁴ + B ・ X ⁶ + C ・ X ⁸ + D ・ X
¹⁰ +. ． It is a curved surface obtained by rotating a curve represented by

It is necessary to measure such an aspherical shape,
Often occurs. Consider, for example, the case of manufacturing a "lens having an aspherical shape" by a molding technique using a mold. First, in the process of manufacturing the mold, the shape of the mold exactly corresponds to the aspherical surface to be formed. It becomes necessary to measure whether or not

Further, the "aspherical surface shape" must be measured when "extraction inspection" is performed to determine whether or not the aspherical surface formed as a lens surface by molding has the shape as designed.

Furthermore, "aspherical surface evaluation" is often required to determine how accurately the aspherical surface shape measured as described above accurately realizes the "target designed aspherical surface shape". .

As a method of measuring the surface shape of an object,
A "stylus" that can be displaced in the vertical direction is moved so that the tip end thereof makes light contact with the surface and traces the surface shape in one direction, and the stylus is displaced in one direction of the surface by the amount of vertical displacement. There is known a "contact type" measuring method for measuring the shape of a circle, that is, the "sectional shape".

Further, the parallel light flux is focused on the object surface by the objective lens, and the objective lens is moved so that the irradiation position changes in one direction along the surface shape while maintaining the direction of the optical axis of the objective lens. A "non-contact type" measuring method is also known in which the cross-sectional shape of the object surface is measured by "the amount of displacement of the objective lens in the optical axis direction" for maintaining the in-focus state.

In these contact-type and non-contact-type shape measuring methods, the moving direction of the stylus and the objective lens is called the "scanning direction".

Each of the above measuring methods can be directly used for measuring the cross-sectional shape of an aspherical surface. However, if the “inclination” on the aspherical surface becomes large, the contact state between the stylus and the aspherical surface or the focused state of the light beam becomes unstable, and accurate measurement cannot be performed.

For example, when the lens 0 of the meniscus in FIG. 7 (a) is the "subject" and its concave surface 0b is the "aspheric surface" to be measured, the line orthogonal to the optical axis AX is taken as the base line and the aspheric surface is taken. When the inclination angle θ of the surface at is represented as a function of the distance from the optical axis AX, the result is as shown in FIG. 7B.

As a specification, the measuring device for carrying out each of the above measuring methods has a measurable limit value: θ with respect to an inclination angle: θ.
₀ is determined, and it is impossible to measure a portion with a tilt angle larger than the limit value: θ ₀ (a portion apart from the optical axis AX on the aspherical surface 0b).

In such a case, FIG. 7 (c-1), (c-
As shown in 2), when the lens 0 of the subject is rotated by ± α around the “axis passing through the optical axis and orthogonal to the optical axis”,
Changes in the tilt angles in the regions A and B shown in (c-1) and (c-2) are as shown in FIG. 7D, and both regions A and B on the aspherical surface 0b can be measured.

Therefore, the aspherical surface shape is measured separately for the areas A and B, and the shape data DA for the area A and the shape data DB for the area B are measured as shown in FIG.
By connecting and so that the overlapping portions match, the entire shape (cross-sectional shape) of the aspherical surface 0b of the lens 0 can be obtained.

However, when this was actually executed, it was found that there were the following problems. That is, when the shape data DA and DB are joined together as shown in FIG. 7E, the overlapping portion of the shape data is often an “approximate spherical surface” in the region near the optical axis of the aspherical surface, and It is not always easy to determine the state in which the shapes match best, and it may take a long time to join the shape data, or the joined shapes may differ from the original shapes.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and a novel cross-sectional shape that can be accurately measured even when the inclination angle of the subject on the aspherical surface is large. It is intended to provide a method for measuring an aspherical surface shape (claims 1 to 6).

Another object of the present invention is to provide a novel aspherical surface shape measuring apparatus for carrying out the aspherical surface shape measurement (claim 7).

Another object of the present invention is to provide an aspherical surface evaluation method for evaluating a measured aspherical surface (claim 8).

[0019]

The aspherical surface shape measuring method of the present invention is a method of measuring "a cross-sectional shape of an aspherical surface of a subject surface".

The aspherical surface shape measuring method according to claim 1 has the following features.

The object is 1 within the aspherical region of the surface of the object.
The above "marks" are formed, held by the holding means, and set on the tilt stage.

A plurality of "tilt angles" are set by the tilting stage as the tilted state of the subject with respect to the scanning direction of the shape reading means, and a predetermined scanning range is set in accordance with each tilting angle in the adjacent scanning ranges. The shape reading means reads the "portions" so that they overlap.

The shape data of a plurality of scanning ranges by the shape reading means are connected by the data processing means "using the mark portion as a common reference" to synthesize the entire cross-sectional shape.

"Reading so that the portions near the mark overlap" means that two scanning regions are adjacent scanning ranges in which the neighborhoods of the mark portions overlap each other and the portions near the mark including the mark are adjacent. It means that it is commonly read by.

The aspherical surface shape measuring method described in claim 2 has the following features.

The subject has "marks" on both sides of the measurement aspherical surface area on the subject surface, which is held by the holding means and set on the tilt stage.

"Two tilt angles" are set by the tilt stage as the tilted state of the object with respect to the scanning direction of the shape reading means, and the scanning ranges corresponding to the respective tilt angles partially overlap each other by the shape reading means. Read.

The two shape data relating to the two scanning ranges by the shape reading means are “joined by the data processing means so that the shapes of the overlapping portions match with each other on the basis of the mark portion” to synthesize the entire cross-sectional shape. .

In the aspherical surface shape measuring method according to the second aspect, "marks formed in a convex or concave shape" are used as marks on both sides of the measurement aspherical surface area of the object surface, and the distance between these marks in the scanning direction is used. : L is given as data for data processing, the positional relationship between the two shape data is determined so that the distance between the mark portions becomes L, and then the shape data is connected so that the shapes of the overlapping portions match each other. The entire cross-sectional shape can be synthesized (claim 3).

Similarly, in the aspherical surface shape measuring method according to the second aspect, "edge surface portions outside the measurement aspherical surface area" are used as marks on both sides of the measurement aspherical surface area on the surface of the object, and the edge surface portions are on the same straight line. After the positional relationship between the two shape data is determined so as to be positioned at, the overall cross-sectional shape can be synthesized by connecting the shape data so that the shapes of the overlapping portions of the shape data match each other (claim 4).

In the aspherical surface shape measuring method according to the fifth and sixth aspects, the object having the aspherical surface is held by the holding means and set on the tilt stage, and the object is tilted with respect to the scanning direction of the shape reading means. , Two tilt angles are set by the tilt stage.

The scanning ranges corresponding to the respective inclination angles are read by the shape reading means while partially overlapping each other.

The two shape data relating to the two scanning ranges by the shape reading means are connected by the data processing means so that the shapes of the overlapping portions match, and the entire cross-sectional shape is synthesized.

In the aspherical surface shape measuring method according to the fifth aspect, "the distance between positions occupied by the same aspherical surface portion according to two inclination angles: s is given as data for data processing, and the distance between the two shape data is calculated. : After giving a relative displacement of s, give relative rotation to the two shape data and connect them so that the shapes of the overlapping parts of each shape data match and synthesize the entire cross-sectional shape ”. And

In the aspherical surface shape measuring method according to the sixth aspect, "a rotation angle: t corresponding to two inclination angles of the same aspherical surface portion is given as data for data processing, and an angle:
After giving a relative rotation of t, a relative translational displacement is given to the two shape data, and they are connected so that the shapes of the overlapping portions of each shape data match and the entire cross-sectional shape is synthesized. ” Characterize.

An aspherical surface shape measuring apparatus according to a seventh aspect of the present invention performs the aspherical surface shape measuring method according to the first, second, third, fourth, fifth or sixth aspect to obtain "a cross-sectional shape of an aspherical surface of a subject. And a shape reading unit, a tilt stage, a holding unit, and a data processing unit.

The "shape reading means" scans the aspherical surface of the subject surface in a predetermined direction over a predetermined scanning range,
Means for reading the shape of the aspherical surface within the scanning range, and means for carrying out the known "contact and non-contact shape measuring method" as described above can be appropriately used.

The "predetermined direction" is the above-mentioned "probe".
Is the direction of movement while tracing the aspherical shape, or the direction in which the "objective lens" moves along the aspherical shape while maintaining the optical axis direction, and this direction is the "scanning direction" of the shape reading means. Further, the scanning range of the stylus and the objective lens is the “scanning range”.

The "tilt stage" is a means for setting a predetermined tilt angle on the surface of the object with respect to the shape reading means, and the "predetermined tilt angle" means that the tilt stage scans the object in the "scanning direction of the shape reading means". It is given by rotating about an "axis orthogonal to". A "gonio stage" is suitable as the tilt stage.

The "holding means" is a means for holding the subject and fixing it to the tilt stage.

The "data processing means" is a means for processing the data read by the shape reading means, and the shape data read by being divided into two or more parts are connected to each other at overlapping portions to form an overall cross-sectional shape. Performs "data processing" to synthesize. This data processing means can be specifically configured by using a "computer or a dedicated CPU".

The “aspherical surface evaluation method” described in claim 8 is a cross-sectional shape of an aspherical surface obtained by the aspherical surface shape measuring method according to any one of claims 1 to 6, and a reference aspherical surface sectional shape. Is calculated and evaluated to evaluate the degree of approximation of the cross-sectional shape of the aspherical surface to the reference aspherical cross-sectional shape.

Here, the "reference aspherical sectional shape" is, for example,
It is a designed “aspherical shape (cross-sectional shape)” designed as the shape of the surface of the optical element.

[0044]

According to the first aspect of the invention, the object has a mark on the aspherical surface portion, and the shape data obtained for each scanning range is:
It is connected so that the overlapping parts may coincide with each other using the mark as a common reference.

According to the present invention as defined in claims 2 to 6, the shape reading is performed in two scanning ranges where the aspherical surface has an overlapping portion with each other, and two shape data are obtained.

Since the shape data is basically a plane figure, the degree of freedom in its arrangement is 2, and the degree of freedom in determining the positions of the two shape data is 4.

In the invention according to claim 3, among the four degrees of freedom, the positional relationship of the mark portions in each shape data is determined by the linear interval: L.
A "rotational displacement" is left as a displacement having one degree of freedom. Therefore, basically, it is possible to join the shape data by adjusting the rotation of each shape data.

In the invention according to claim 4, "the mark is the edge surface"
Since the shape obtained by reading this is a straight line portion, if each mark is positioned on the same straight line, the degree of freedom left in each shape data is only the change in the mutual distance. It is possible to connect two shape data by relatively displacing them in parallel with the same straight line.

According to the fifth aspect of the present invention, since how far the same positions in the two shape data are apart from each other during shape reading is given as a distance: s, after the same positions are separated from each other by the distance: s. Allows the shape data to be joined by adjusting the rotation of the shape data.

According to the sixth aspect of the present invention, since the same position in the two shape data forms an angle about the rotation axis of the tilting stage when the shape is read, as an angle: t, 2 After the relative rotation of the angle: t is given to one shape data, the mutual connection can be performed by adjusting the mutual interval of the quantity shape data.

[0051]

EXAMPLES Specific examples will be described below. FIG. 1 schematically shows an embodiment of an aspherical surface shape measuring apparatus according to claim 7.

Reference numeral 0 indicates a subject. Reference numeral 10 indicates a goniometer stage as the "tilt stage". Reference numeral 16 denotes a shape reading device as "shape reading means", which may be a contact type or a non-contact type, but the aspherical surface of the subject 0 (the surface facing the shape reading device 16) is oriented in the left-right direction in the drawing. Scanning is performed in the "scanning direction", and the aspherical shape is converted into data in the scanning direction to obtain "shape data".

The control / calculation device 18 to which the shape data is input is a computer and forms a main part of "data processing means". The data processing means also has a display 19, a printer 20, and a keyboard 22. In this example,
The control / arithmetic unit 18 can control the gonio stage 10 via the drive unit 24.

Hereinafter, the case where the "meniscus lens described with reference to FIG. 7" is used as the subject 0 and the concave shape is measured by the method according to any one of claims 1 to 6 by the apparatus of this embodiment explain.

As shown in FIG. 1, the lens 0, which is the subject, is held by the holder 12 and is set on the goniometer stage 10 with the concave side, which is the object of measurement, facing the shape reading device 16. The lens 0 is fixed to the holding body 12 by the holding ring 14. That is, the holding body 12 and the retaining ring 1
4 constitutes "holding means".

FIG. 2 is a diagram for explaining one embodiment of the invention described in claim 1.

The aspherical surface (concave surface) of the lens 0 is shown in FIG.
As shown in the above figure, the surface including the optical axis AX is the object of scanning with the left-right direction of the figure as the scanning direction, but the mark M is formed as a minute "cut" at the substantially central portion in the scanning direction. There is. The mark may be formed in a “projection shape”.

As described above, in the method according to the first aspect, the mark is formed on the aspherical surface portion of the subject. Since the mark M is a "scratch" on the lens surface of the lens 0, the lens as the measurement object is usually not "useful".

Therefore, in the method according to claim 1, the shape of the aspherical surface forming die is inspected (whether or not the molding surface shape as designed is obtained is transferred as a lens surface and measured. ) Or a sampling inspection of the product lens (measuring whether or not the lens surface of the product lens is formed into a desired aspherical shape) is effective.

The aspherical surface of the lens 0 is divided into two scanning ranges A and B in which the vicinity of the mark M is overlapped, as shown in the lower diagram of FIG. When the lens 0 is set on the goniometer stage and is rotated about an axis orthogonal to the scanning direction to give an inclination angle, and the shapes of the scanning ranges A and B are read, according to the shapes of the scanning ranges A and B, as shown in FIG. (B) As shown in the above figure, two shape data DA and DB are obtained.

These two pieces of shape data DA and DB are subjected to data processing, and the mark portions are connected as a common reference to synthesize the entire cross-sectional shape. This is a data processing means, which is a control / calculation unit 18 (see FIG. It is performed according to the program in 1).

Although various methods can be used as a concrete method of joining, for example, the following method is used. As shown as a flow chart in FIG. 2 (c), first, the tip end portions PMA, P of the marks in the shape data DA, DB shown in the upper diagram of FIG. 2 (b).
Match MB. This is mainly performed by translating the shape data DB relative to the shape data DA (upper part (1) of FIG. 2B).

When the tip portions PMA and PMB match, the shape data DA is rotated clockwise and the shape data DB is rotated counterclockwise (FIG. 2B, upper drawing (2)), and the vicinity of the mark is overlapped. Match the data in the parts. In this way,
The cross-sectional shape DA + D of the entire aspherical surface as shown in the lower diagram of FIG.
B is obtained.

FIG. 3 is a diagram for explaining one embodiment of the invention described in claims 2 and 3.

As shown in FIG. 3A, the lens 0, which is the subject, has a ring groove-shaped mark m of diameter L formed on the "edge surface" portion outside the measurement aspherical surface area. There is.
The mark may be formed in a “convex shape”.

Therefore, when the "scanning direction" is set as shown in the upper diagram of FIG. 3 (a), the marks mA and mA are provided at "both sides of the measured aspherical surface area of the subject surface" as shown in the lower diagram of (a). There will be.

The lens 0 is set on the goniometer stage, two inclination angles are set by the inclination stage as the inclination state of the subject with respect to the scanning direction of the shape reading means, and the lower diagram of FIG. The scanning ranges A and B set as above are read. Of course, the scanning ranges A and B include marks mA and mA, respectively.

As shown in the upper diagram of FIG. 3B, the two shape data D relating to the two scanning ranges A and B are obtained by reading.
A and DB are obtained. These pieces of shape data DA and DB are connected to each other so that the shapes of the overlapping portions match each other with reference to the marks mA and mB, and the entire cross-sectional shape is synthesized.

In this embodiment, the procedure of the flow chart of FIG. 3C is followed. That is, first, the shape data DA and DB are moved in parallel as shown in the upper diagram of FIG. 3B so that the mark data DmA and DmB are positioned so that they are separated by a linear distance L (diameter of the ring-shaped mark m). (Fig. 3 (b) upper diagram (1)).

Then, the shape data DA and DB are respectively rotated clockwise and counterclockwise to generate the shape data D.
Match the overlapping parts of A and DB. In this way, the sectional shape of the entire aspherical surface is obtained. Data: L is input as a condition value at the time of measurement from the keyboard 22 of FIG.

FIG. 4 is a diagram for explaining one embodiment of the invention described in claims 2 and 4.

The lens 0 which is the subject has a "edge surface" formed outside the measurement aspherical surface area. Figure 4 (a)
In FIG. 5, reference symbols a and b indicate “edge surfaces on both sides in the scanning direction”. That is, the edge surface portions a and b are marks on both sides of the measurement aspherical surface area on the surface of the subject.

The lens 0 is set on the goniometer stage, two tilt angles are set by the tilt stage as the tilt state of the object with respect to the scanning direction of the shape reading means, and the scanning range A, which is set according to each tilt angle, is set. Read B so that it partially overlaps. Of course, each of the scanning ranges A and B includes the edge surface portions a and b that are marks, respectively.

By reading, as shown in the upper diagram of FIG. 4B, two shape data D regarding two scanning ranges A and B are obtained.
A and DB are obtained. Hereinafter, these shape data DA,
The DBs are connected so that the shapes of the overlapping portions match with each other with reference to the mark portion, and the entire cross-sectional shape is synthesized.

In this embodiment, the procedure of the flow chart of FIG. 4C is followed. That is, first, the shape data DA and DB are rotated clockwise and counterclockwise, respectively, as shown in the upper diagram of FIG. 3B to obtain the data D corresponding to the edge surface portions a and b.
Make a and Db coincide with the reference straight line.

After that, the shape data DA and DB are relatively moved in parallel along the above-mentioned reference straight line to match the overlapping portions. In this way, as shown in the lower diagram of FIG. 2B, the cross-sectional shape DA + DB of the entire aspherical surface is obtained.

FIG. 5 is a diagram for explaining one embodiment of the invention described in claim 5.

Stage 11 in the goniometer stage 10
A tilt angle is given to the subject 0 by tilting.
The rotation center Q of the stage 11 is fixed as a fixed position relative to the goniometer stage.

Therefore, the aspherical surface of the subject set on the goniometer stage by the holding means is set to a state where the inclination angle is 0,
By measuring the vicinity of the center of the aspherical surface, the distance H between the center of rotation Q and the center of the aspherical surface can be known.

In FIG. 5A, angles: α _A and α _B are inclination angles set for shape reading of the left half and right half of the lens 0, which is the subject, respectively.

Although "how to set the inclination angle" was not particularly described in the embodiments of FIGS. 2 to 4, the same as in FIG. 5A is also applied to the embodiments of FIGS. Tilt angle setting "
Is done.

When the tilt angles α _A and α _B are set as described above, the "center of the aspherical surface" of the lens 0 is determined by reading the right half scanning range and reading the left half scanning range. , Distance: s = H · sin α _A + H · sin α _B.

At this time, the inclination angles α _A and α _B are changed to | α _A | =
If | α _B | = α is set, the distance: s is 2H · sin α
Becomes

As shown in the upper diagram of FIG. 5B, the shape data obtained by reading the two scanning ranges with the inclination angle set as described above corresponds to the scanning range on the left side, the shape data DA, and the scanning on the right side. The shape data DB corresponds to the range. The two scanning ranges overlap in the area near the center of the aspherical surface.

If the central portion of the aspherical surface is PA for the shape data DA and PB for the shape data DB, these are "the same portion on the aspherical surface" and the distance: s
I know they are only apart.

Therefore, this distance: s is given as "data for data processing" (input with the keyboard 22 in FIG. 1). In addition, input the inclination angle ± α with the keyboard 22,
The control / arithmetic unit 18 controls the rotation angle of the goniometer stage via the drive unit 24 so that the set incident angle is accurately realized.

In this case, the connection of the shape data is
The process is performed as shown in the flowchart of FIG. First, a relative distance: s so that the shape data DA and DB are close to each other.
Is given (Fig. 5 (b) upper diagram (1)), the data portion P
Match A and PB.

Then, by rotating the shape data DA clockwise and the shape data DB counterclockwise respectively by an angle of α, the overlapping portions can be made to coincide with each other, and the sectional shape DA + DB of the entire aspherical surface (see FIG. 5 ( b) The figure below is obtained.

FIG. 6 is a diagram for explaining one embodiment of the invention described in claim 6.

Similar to FIG. 5, FIG. 6 (a) is an explanatory view showing a state in which the tilt angle: α _A , α _B is given to the subject 0 by tilting the stage 11 of the gonio stage 10. . Reference numeral Q indicates the center of rotation of the stage 11. In this case as well, | α _A | = | α _B | = α is set. Then, the corner t in FIG. 6A is 2α.

In practice, the keyboard 22 shown in FIG.
Enter t. Then, the control / arithmetic unit 24 becomes the drive unit 2
Goniometer 10 via 4 to 2 tilt angles: ± t
/ 2 (= ± α) is sequentially set.

As shown in the upper diagram of FIG. 6B, the shape data obtained by reading the two scanning ranges with the tilt angle set as described above corresponds to the scanning range on the left side, the shape data DA, and the scanning on the right side. The shape data DB corresponds to the range. The two scanning ranges overlap in the area near the center of the aspherical surface.

The connection of the shape data Da and DB is
The process is performed as shown in the flowchart of FIG. First, the shape data DA is rotated in the clockwise direction and the shape data DB is rotated in the counterclockwise direction by an angle of α (= t / 2).

Subsequently, the shape data DA and DB are relatively moved in parallel to match the overlapping portions. In this way, the cross-sectional shape DA + DB of the entire aspherical surface (lower diagram of FIG. 6B) is obtained.

The aspherical surface is often measured for the purpose of "evaluating the aspherical surface to be measured". For example, in the case of "confirming the shape of the mold" during the manufacturing of the mold described above or in the case of "lens extraction inspection",
The shape of the mold and the lens surface shape are expected to have a predesigned reference aspherical surface, and the measured aspherical cross-sectional shape is the degree of approximation to the reference aspherical cross-sectional shape, that is,
How close to the reference aspherical cross-sectional shape is the target of evaluation.

Since the reference aspherical surface is predetermined and accurately known, the data of the reference aspherical surface sectional shape is input from the keyboard 22 of FIG. 1 and obtained by the control / arithmetic unit 18 as described above. The evaluation can be performed by comparing with the “cross-sectional shape of the entire aspherical surface” as the measurement result.

Various "algorithms" for evaluation can be used. For example, the variable in the aspherical expression: the coordinate of X:
For X _i (i = 1, 2, 3 ...), the difference between the reference aspherical surface sectional shape: Z (X _i ) and the measured sectional shape: z (X _i ):
The sum of squares of ΔZ _i (= Z (X _i ) −z (X _i )): Σ (ΔZ _i ) ² can be used as the evaluation parameter. Σ (Δ
The smaller Z _i ) ² is, the closer the measured cross-sectional shape is to the reference aspherical cross-sectional shape.

For example, in the case of sampling inspection of a lens having an aspherical shape, the aspherical surface of the lens to be inspected is measured by the above-described method to obtain a sectional shape for the entire aspherical surface.
"Evaluate" this cross-sectional shape with the evaluation parameters as described above.
However, if the evaluation parameter has a size equal to or smaller than a certain value, the lens to be inspected can be a “passed product”, and the others can be a “defective product”.

The result of the above measurement or evaluation can be output to the display 19 and / or the printer 20 in FIG.

In carrying out the aspherical surface measuring method according to the first aspect of the present invention, the case of dividing the entire aspherical surface into two scanning ranges has been described above, but it may be divided into three or more scanning ranges as necessary. It goes without saying that you can do it.

Depending on the number of divisions: n, the number of marks: n-1
It is natural to increase When two or more marks are provided, it is usually necessary to form the marks so that the entire measurement area is equally divided. However, when the slope of the surface is strong, the gap between the marks is short, and when the slope of the surface is weak, The marks may be formed at "unequal intervals" by increasing the intervals.

[0102]

As described above, according to the present invention, a novel aspherical surface shape measuring method and apparatus / aspherical surface evaluating method can be provided (claims 1 to 8).

The aspherical surface shape measuring method according to the present invention (claim 1
Since (6) to (6) are configured as described above, it is possible to easily and surely measure an aspherical surface having a large inclination, which cannot be measured conventionally.

In the aspherical surface shape measuring method according to the second to fourth aspects of the present invention, since the mark is outside the measurement area of the aspherical surface shape, the aspherical surface is not damaged by the mark.

Since the aspherical surface shape measuring method according to the fifth and sixth aspects of the present invention is configured as described above, the aspherical surface shape can be measured without marking the subject.

The aspherical surface shape measuring apparatus of the present invention (claim 7) can reliably carry out the aspherical surface shape measuring method according to any one of claims 1 to 6.

Further, according to the aspherical surface evaluation method of the present invention (the eighth aspect, it is possible to evaluate the degree of approximation of the aspherical surface shape measured by the above measuring method to the reference aspherical surface sectional shape.

[Brief description of drawings]

FIG. 1 is a diagram for explaining one embodiment of an aspherical surface shape measuring apparatus of the present invention.

FIG. 2 is a diagram for explaining one embodiment of the invention according to claim 1;

FIG. 3 is a diagram for explaining one embodiment of the invention described in claims 2 and 3.

FIG. 4 is a diagram for explaining one embodiment of the invention described in claims 2 and 4.

FIG. 5 is a diagram for explaining one embodiment of the invention according to claim 5;

FIG. 6 is a diagram for explaining one embodiment of the invention according to claim 6;

FIG. 7 is a diagram for explaining a conventional technique and its problems.

[Explanation of symbols]

 0 Subject M Mark

Claims (8)

[Claims] 1. A method for measuring a cross-sectional shape of an aspherical surface of an object surface, comprising: holding an object having one or more marks formed in an aspherical surface area of the object surface by a holding means, on an inclined stage. The tilt angle of the object with respect to the scanning direction of the shape reading means is set by a tilting stage, and a predetermined scanning range is set in accordance with each tilt angle, and a predetermined scanning range is set in the adjacent scanning range in the vicinity of the mark. The shape reading means reads the shapes so that the portions overlap, and the shape data of a plurality of scanning ranges by the shape reading means are connected by the data processing means with the mark portions as a common reference to synthesize the entire cross-sectional shape. Characteristic aspherical surface shape measuring method. 2. A method for measuring the cross-sectional shape of an aspherical surface of a subject surface, wherein the subject having marks on both sides of the measurement aspherical surface region of the subject surface is held by holding means and set on an inclined stage. Then, two tilt angles are set by the tilt stage as the tilt state of the subject with respect to the scanning direction of the shape reading means, and the scanning ranges corresponding to the respective tilt angles are partially overlapped with each other and read by the shape reading means. It is characterized in that the two shape data relating to the two scanning ranges by the shape reading means are connected by the data processing means so that the shapes of the overlapping portions match with each other with the mark portion as a reference to synthesize the entire cross-sectional shape. Aspherical shape measurement method. 3. The aspherical surface shape measuring method according to claim 2, wherein the marks on both sides of the measurement aspherical surface area on the surface of the object are marks formed in a convex shape or a concave shape, and between the marks in the scanning direction. Distance: L is given as data for data processing, the positional relationship between the two shape data is determined so that the distance between the mark parts becomes L, and then the shape data is connected so that the shapes of the overlapping parts match. An aspherical surface shape measuring method, characterized by synthesizing the entire cross-sectional shape. 4. The aspherical surface shape measuring method according to claim 2, wherein the marks on both sides of the measurement aspherical surface region of the object surface are edge surfaces outside the measurement aspherical area, and the edge surface portions are on the same straight line. Aspherical shape measurement, characterized in that after defining the positional relationship between the two shape data so that they are located at Method. 5. An object having an aspherical surface is held by a holding means and set on an inclination stage, and two inclination angles are set by the inclination stage as an inclination state of the object with respect to the scanning direction of the shape reading means. The scanning ranges corresponding to the respective tilt angles are partially overlapped with each other and are read by the shape reading means, and the two shape data relating to the two scanning ranges by the shape reading means are matched by the data processing means in the shapes of the overlapping portions. In the aspherical surface shape measuring method for synthesizing the whole aspherical surface shape by connecting as described above, the same aspherical surface portion between the positions occupied by two inclination angles The distance: s is given as data for data processing, the relative displacement of the distance: s is given to the two shape data, and then 2
A method for measuring an aspherical surface shape, wherein relative rotation is applied to one shape data piece, and the shape is overlapped so that the shapes of overlapping portions of the shape data pieces are combined to synthesize the entire cross-sectional shape. 6. An object having an aspherical surface is held by a holding means and set on an inclination stage, and two inclination angles are set by the inclination stage as an inclination state of the object with respect to the scanning direction of the shape reading means. The scanning ranges corresponding to the respective tilt angles are partially overlapped with each other and are read by the shape reading means, and the two shape data relating to the two scanning ranges by the shape reading means are matched by the data processing means in the shapes of the overlapping portions. In the aspherical surface shape measuring method for synthesizing the entire cross-sectional shape by connecting the two as described above, the rotation angle: t corresponding to two inclination angles of the same aspherical surface portion is calculated. Data is given as data for processing, two pieces of shape data are given relative rotations of angle: t, and then two pieces of shape data are given relative translational displacements to obtain the weight of each piece of shape data. Aspheric shape measuring method characterized by synthesizing the entire cross-section shape of the portion is joined to match. 7. An apparatus for measuring a cross-sectional shape of an aspherical surface of a subject surface, comprising scanning the aspherical surface of the subject surface in a predetermined direction over a predetermined scanning range to obtain an aspherical surface within the scanning range. The shape reading means for reading the shape, the tilt stage for setting a predetermined tilt angle on the surface of the subject with respect to the shape reading means, the holding means for holding the subject and fixing them to the tilt stage, and the shape reading means. An aspherical surface shape measuring apparatus for carrying out the aspherical surface shape measuring method according to claim 1, which has a data processing means for processing read data. 8. The difference between the cross-sectional shape of the aspherical surface obtained by the aspherical surface shape measuring method according to claim 1 or 2 or 3 or 4 or 5 or 6 and the reference aspherical surface cross-sectional shape is calculated and calculated, An aspherical surface evaluation method characterized by evaluating the degree of approximation of a cross-sectional shape of an aspherical surface to a reference aspherical surface cross-sectional shape.