JPH11325828A - Center position measuring method of concave surface, eccentric amount measuring method and measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable quantitative measurement of center position with high precision, in the case of an optical component having a large radius of curvature, by measuring coordinates of a specified number of points on a circle surrounded by a plane formed by cutting the periphery of a concave surface of an optical component, and calculating the center position of the circle from the coordinates. SOLUTION: An optical component 10 in which the periphery of a concave surface A is cut and a plane 26 is formed is mounted on a moving table 22, and observed with a differential interference microscope 21. The concave surface A and the plane 26 are discriminated and seen. The boundary of the concave surface A and the plane 26 can be visually recognized as a circle 27. The moving table 22 is moved, at least three arbitrary points on the circle 27, e.g. four points, are made to coincide with the point of intersection of a cross line fitted to an eyepiece, and coordinates of the four points A1 -A4 are obtained. The coordinates are inputted in operating equipment 24. By starting a software for center position calculation which is stored in the operating equipment 24, the center position C1 of the circle 27 is calculated. Calculated results and the inputted coordinates A1 -A4 are outputted by a printer 25.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the center position of a concave surface, a method for measuring the amount of eccentricity, and a method for specifying the center position of a concave surface of an optical component such as a concave lens or a concave mirror and measuring the correct center position. The present invention relates to a measuring device used for a measuring method.

[0002]

2. Description of the Related Art FIG. 5 shows a conventional centering and centering apparatus. The optical component 10 having the concave surface A is sandwiched by a pipe-shaped bell chuck 11, and the optical component 10 is slid with respect to the bell chuck 11 in a direction orthogonal to the axis 12 of the bell chuck 11 so that the tip of the bell chuck 11 is Search for a state of uniform contact with the concave surface A. By detecting a state in which the tip of the bell chuck 11 makes uniform contact with the concave surface A, in that state, the thickness of the optical component 10 sandwiched between the bell chuck 11 is uniform in the front and back directions. Which means that the axis of the concave surface A coincides with the axis of the bell chuck 11.

In this state, the outer diameter grinding machine 13 is rotated to cut the outer periphery of the optical component 10 so that the optical component 10 is cut.
Can be removed. Here, the optical component 1
Reference numeral 0 denotes a concave lens or a concave mirror made of, for example, glass. FIG. 6 shows another example of a conventional method for measuring the center position of a concave surface. In this example, an autocollimeter 14 and a support shaft 15 rotating coaxially with the autocollimeter 14 are used, and the optical component 10 is heated and bonded to the tip of the support shaft 15 with hot melt wax 16 or the like, An image of a parallel light beam is formed and checked with the eyes via a crosshair reticle 14A, and the optical component 10 is adjusted in the direction perpendicular to the axis 12 by moving the mounting position to adjust the optical axis of the optical component 10.
Perform centering.

FIG. 7A shows the locus of the light spot MO when the centering is incomplete. FIG. 7B shows the trajectory of the light spot MO after the centering is completed. After the centering is completed, the light spot MO does not move even if the optical component 10 is rotated.

[0005]

According to the above-described conventional centering method, centering cannot be performed particularly with the centering method shown in FIG. 5 if the radius of curvature of the concave surface A formed on the optical component 10 is large. Met. In addition, it is impossible to provide an arbitrary amount of eccentricity even for an optical component having a small radius of curvature. Furthermore, the amount of eccentricity could not be quantitatively measured.

Further, according to the center position measuring method shown in FIG. 6, the radius of curvature of the concave surface A can be dealt with up to about several hundred mm.
However, it cannot cope with an optical component having a radius of curvature of several thousand mm. Further, when the support shaft 15 and the optical component 10 are bonded with the hot melt wax 16, it is almost impossible to bond the support shaft 15 and the optical component 10 in parallel each time at the time of bonding. In many cases, the centering does not converge and diverges.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the conventional drawbacks, and to provide a method of measuring the center position of a concave surface capable of measuring the center position with high accuracy and quantitatively even with an optical component having a radius of curvature of several thousand mm class. An object of the present invention is to provide a method and an apparatus for measuring a quantity.

[0008]

According to a first aspect of the present invention, a flat surface is formed by cutting a peripheral edge of a concave surface of an optical component having a concave surface, and at least three edges of a circle formed by the flat surface are formed. The coordinates of the point are measured, the center position of the circle is calculated from the coordinates, and a method of measuring the center position of the concave surface that determines the center position of the calculated circle as the center position of the concave surface is proposed.

According to the method for measuring the center position of a concave surface proposed in claim 1, since the cut surface of the concave surface (part of the spherical surface) is a perfect circle, at least three coordinates on the perfect circle are measured. Thus, the center position of the concave surface can be accurately calculated. In addition, even if the radius of curvature of the concave surface is large, the center position of the optical component can be accurately obtained by placing the optical component on the moving table, accurately measuring the moving amount of the moving table, and obtaining coordinates on a circle. .

According to a second aspect of the present invention, in addition to the center position measuring method proposed in the first aspect, at least three coordinates of the peripheral edge of the optical component are measured, and the center position of the outer edge of the optical component is calculated. The deviation between the position and the center position of the concave surface is determined to measure the amount of eccentricity. Therefore, according to the second aspect, since the amount of eccentricity can be accurately obtained, there is an advantage that the machining for removing the eccentric portion can be performed accurately.

According to a fourth aspect of the present invention, there is provided a differential interference microscope capable of observing irregularities existing on the surface of a transparent body such as glass, and a distance measuring device capable of accurately determining the amount of movement. The optical part is placed on the movable table, and the coordinates of the circle formed on the outer periphery of the concave surface are measured by moving the movable table, so that it is possible to accurately determine the center position of the circle. it can.

[0012]

FIG. 1 shows the configuration of a center position measuring device and an eccentricity measuring device according to the present invention. By describing the configuration and operation of this measuring device, the method of measuring the center position of the concave surface and the method of measuring the amount of eccentricity according to the present invention will be described together. In FIG. 1, reference numeral 21 denotes a differential interference microscope. As is well known, the differential interference microscope 21 includes a measuring tool microscope and an eyepiece 21A with a crosshair and an objective lens 21.
B, a light source 21C having a high light emission intensity, and a polarizer 21D.
, An analyzer 21E, and a Nomarski prism 21F, and by adding these configurations, a differential interference function can be obtained in the measuring tool microscope. According to this differential interference function, even if it is transparent like glass,
The unevenness on the surface can be visually recognized by the difference in color, the shade of color, and the like.

Reference numeral 22 denotes a moving table. In this example, the moving table 22X moving in the X direction and the moving table 22 moving in the Y direction
5 shows a case in which a two-axis moving table configured with Y is used. The moving tables 22X and 22Y of the moving table 22 are respectively provided with distance measuring devices 23X and 23Y for measuring a moving amount and transmitting, for example, a pulse corresponding to the moving amount. The coordinate signal transmitted from 23Y is input to an arithmetic unit 24 constituted by a computer. Reference numeral 25 denotes a printer connected to the arithmetic unit 24.

The optical component 10 is placed on the moving table 22,
The surface of the optical component 10 is observed by the differential interference microscope 21. FIG. 2 shows an example of the optical component 10 in which the flat surface 26 is formed on the outer periphery of the concave surface A. When the optical component 10 is observed with a differential interference microscope 21, as shown in FIG. 2, the concave surface A and the flat surface 26 can be distinguished from each other.
Can be visually recognized as a circle 27. Reference numeral 28 shown in FIG. 2 indicates a crosshair attached to the eyepiece 21A.

Therefore, the movable table 22 is moved to
At least three points match the intersection of crosshairs 28
And determine the coordinates at that time. In this example, the coordinates A₁,
A_Two, A_Three, A_Four4 shows the case where four points are obtained. These four points
Coordinates A₁, A_Two, A_Three, A _FourIs input to the arithmetic unit 24.
The calculation of the center position stored in the arithmetic unit 24
Software (Calculate the center position by the least squares method)
Is activated and the center position C of the circle 27 is₁And calculate this
Result and each input coordinate A₁, A_Two, A_Three, A _FourPre
To the center 25.

Further, according to the present invention, on the outer periphery of the optical
Arbitrary coordinates B of₁, B_Two, B_Three, B _FourTo the arithmetic unit 24
Enter the center position M of the optical component 10₁Ask for. This
Central position C of sea urchin 27₁And the center position M of the optical component 10
₁Are obtained, the center position C is obtained.₁And inside
Heart position M₁Is obtained as the eccentricity r of the concave surface A.
Can be In addition, this center position C₁And M₁Tie
Find the intersection angle θ between the line and the reference coordinate axis (Fig. 2).
Thus, the eccentric direction can be defined. Standard
For example, the center position M₁Orthogonal with origin as
Set the coordinates, and set the
The eccentric direction can be determined by obtaining the direction θ.
You.

The centering operation is thus completed, and the outer diameter of the optical component 10 is made to coincide with the center of the concave surface A by performing the outer diameter grinding after offsetting by the eccentric amount r in the θ direction during the centering processing. it can. FIG. 3 shows another example of the measuring device according to the present invention. In this example, one of the movable tables 22 is omitted. In this example, the movable table 22X is omitted.
A tilt error is reduced by using a high-precision rotary table 22C such as an air bearing 22C on the 2Y. A rotary encoder is attached to the air bearing 22C, and the current angle can be displayed on the angle display 23C, and can be input to the arithmetic unit 24. The optical component 10 is coaxial with the rotation axis of the air bearing 22C.
The optical component 10 is held on the chuck 29, and the coordinates on the circle 26 appearing at the boundary between the concave surface A and the plane 26 and the coordinates on the outer periphery of the optical component 10 are transferred to the moving table 22 </ b> Y and the air bearing. 22C to move the measured, it is possible to obtain the respective central positions C ₁ and M ₁ from the measured coordinates.

FIG. 4 shows how the optical component 10 is viewed from the eyepiece 21A shown in FIG. In reality, the same applies to the case of FIG. 1, but the microscope only shows a part of the concave surface A of the optical component 10, for example, but does not show the entire shape of the optical component 10 as shown in the figure.

[0019]

As described above, according to the present invention, the flat surface 26 is temporarily formed on the concave surface A side of the optical component 10,
By observing the surface of the optical component 10 with the differential interference microscope 21, the boundary between the concave surface A and the plane 26 can be visually recognized as a circle 27, and the coordinates of any three points on the circle 27 can be measured. it is possible to obtain the center position C ₁ of the concave surface a.

Further, by measuring the coordinates of three points on the outer periphery of the optical component 10, the center position M ₁ of the optical component 10 can be obtained. As a result, the eccentricity r and the eccentric direction θ can be obtained by obtaining the eccentricity r between the center position C ₁ and the center position M ₁ and the angle θ on the orthogonal coordinate axis as a reference. By calculating the eccentricity r and the eccentric direction θ, the centering operation can be performed around the center position C ₁ moved by the eccentric amount r in the eccentric direction θ from the center position M ₁ of the optical component 10 during the centering operation. The centering operation can be performed easily and reliably.

Further, according to the present invention, there is obtained an advantage that the center position can be accurately obtained even if the radius of curvature of the concave surface A is large. Further, according to the present invention, the amount of eccentricity r can be calculated quantitatively, and conversely, the optical axis can be set at a position decentered by an arbitrary amount. Furthermore, the outer shape of the optical component can obtain the center position C ₁ and M ₁ even if any shape not limited to a circle, its effect is extremely large and practically.

[Brief description of the drawings]

FIG. 1 is a side view for explaining an example of a measuring apparatus according to the present invention.

FIG. 2 is a plan view for explaining the operation of FIG. 1;

FIG. 3 is a side view showing another example of the measuring device according to the present invention.

FIG. 4 is a plan view for explaining the operation of FIG. 3;

FIG. 5 is a sectional view seen from a side for explaining a conventional technique.

FIG. 6 is a sectional view seen from a side for explaining another example of the related art.

FIG. 7 is a view for explaining the operation of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Optical component A Concave surface 21 Differential interference microscope 22 Moving table 23X, 23Y Distance measuring device 24 Computing device 25 Printer 26 Plane

Claims (4)

[Claims] 1. A flat surface is formed by cutting the periphery of the concave surface of an optical component having a concave surface, and coordinates of at least three points on a circle formed by being surrounded by the flat surface are measured. A method of measuring the center position of the concave surface, which calculates the center position of the circle and determines the calculated center position as the center position of the concave surface. 2. A flat surface is formed by cutting the periphery of the concave surface of the optical component having the concave surface, and the coordinates of at least three points on a circle formed by being surrounded by the flat surface are measured. The center position of the circle is calculated, the calculated center position is determined as the center position of the concave surface, the coordinates of at least three points on the outer periphery of the optical component are measured, and the center position of the optical component is calculated from the coordinates. The distance between the center position of the outer circumference and the center position of the circle is defined as the amount of eccentricity. 3. The eccentricity measuring method according to claim 2, wherein a direction of a line connecting a center position of an outer periphery of the optical component and a center position of the circle is defined as an eccentric direction. 4. A. B. a differential interference microscope capable of distinguishing and visually recognizing irregularities on the surface of the transparent member; The members observed by the differential interference microscope are defined in the X direction and the Y direction.
B. a carriage that can be moved in known directions by a known amount; D. a distance measuring device that outputs the moving position of the moving table as a coordinate signal; A measuring device configured to obtain a center position of the circle and a center position of the outer periphery by taking in a coordinate signal generated by the distance measuring device.