JPH0139045B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the radius of spherical curvature of a concave spherical surface or a convex spherical surface using a laser interferometer, and its main object is to enable rapid and highly accurate measurement.

In general, laser interferometers are often used to measure the radius of curvature of uneven spherical surfaces such as hydrodynamic bearings. The principle of measuring the radius of curvature of a spherical surface using this laser interferometer is well known, and the principle of measurement will be explained with reference to FIG. First, adjustment is made so that the laser beam 2 incident parallel to the reference spherical lens 1 of the laser interferometer is converged at a focal point 4 on the optical axis 3. Next, the center of the spherical surface of the object to be measured 5 whose radius of curvature is to be measured is aligned with the optical axis 3. When the interference fringes are observed while the object to be measured 5 is moved along the optical axis 3, the center of the spherical surface of the object to be measured 5 coincides with the focal position 4, and the surface of the object to be measured 5 is at a position A. A position B that coincides with the focal position 4 can be detected. Since the moving distance r between the positions A and B matches the radius of curvature of the object to be measured 5, the radius of curvature can be precisely determined by accurately measuring the moving distance r.

Conventionally, when reading the positions of A and B, or the distance r between A and B, the slide table with the object to be measured 5 mounted thereon is moved by a screw, and the moving distance r of the slide table is measured using a scale plate or the like. It was read with a dial cage etc. Therefore, with conventional devices, it takes time to feed the screws of the sliding table, and it is difficult to perform accurate measurements due to the influence of accumulated errors in the scale plate, dial gauge, etc. In particular, when the radius of curvature of the object to be measured 5 is several mm to several tens of mm or more, the screw feeding time of the sliding table becomes extremely long, and the longer the measurement distance, the more the cumulative error of the dial gauge etc. increases. There was a growing flaw. Furthermore, when the object to be measured 5 is the same product that is mass produced, it is difficult to shorten the measurement time, which is a major problem in mass production.

In view of the above-mentioned conventional drawbacks, the present invention improves and improves the conventional drawbacks.
The structure of the present invention will be explained below with reference to the drawings.

Now, the present invention relates to the measurement of a concave spherical object to be measured.
This will be explained with reference to FIGS. 2 to 4. In FIGS. 2 and 3, 6 is the laser interferometer main body, 7 is the reference spherical lens housing part attached to the interferometer, 8 is the optical axis, 9 is the focal position of the reference spherical lens attached to the interferometer, and 10 is an object to be measured, and 11 is a chuck of the object to be measured 10. 12 is a bed for fixing the entire device; 13
14 and 15 are two dial gauges arranged on the sides of the sliding table 13, and 16 will be described later in the explanation of FIG. 4. This is a reference block. The dial gauge 14 has the center of the spherical surface of the object to be measured 10 at the focal point 9.
The dial gauge 15 is used to read the position of the object 10 in the optical axis direction when the surface of the object 10 coincides with the focal point 9. It is something. Further, the sliding table 13 is manually moved largely in the optical axis direction, and finely adjusted in the optical axis direction using a micrometer 17.

Further, reference numeral 18 denotes an optical axis alignment table fixed on the sliding table 13 and coupled to the chuck 11, and 19 a micrometer 20 for finely adjusting the optical axis alignment table 18 in the vertical direction. These two micrometers 19 and 20 are micrometers that are finely adjusted in a direction perpendicular to the drawing in the figure, and the center of the spherical surface of the object to be measured 10 is aligned with the optical axis 8 via the optical axis alignment table 18. 21 is a stopper for the micrometer 17 fixed to the sliding table 13;
is always lightly pressed against the micrometer 17 via the stopper 21 by a spring (not shown). Further, 22 is a protective stopper for preventing the object to be measured 10 from approaching the reference spherical lens housing 7 more than necessary and damaging the lens; 23 is a handle used when manually moving the sliding table 13; and 24 ，
Reference numeral 25 denotes a stopper that comes into contact with each dial gauge 14, 15.

The reference block 16 shown in FIG.
The reference width a matches the reference radius of curvature of 0, and may be, for example, a block gauge, a reference ball, or an equivalent dimension reference object. The reference block 16 is manually inserted between the stopper 21 of the slide table 13 and the tip 26 of the micrometer 17, and is held by being lightly pressed against both.
Also, when inserting this reference block 16, the sliding base 13
stops at a position moved leftward by dimension a from the initial position, and in this state the stopper 25 is arranged so as to come into contact with the dial gauge 15.

Next, a measurement operation procedure using the above configuration will be described for a case where the radius of curvature of a large number of objects to be measured 10 is sequentially measured.

First, the first object to be measured 10 is attached to the chuck 11, and the optical axis alignment table 18 is moved by operating the micrometers 19 and 20 to align the spherical center of the object to be measured 10 with the optical axis 8. Next, Figures 2 and 3
As shown in the figure, by operating the micrometer 17 without inserting the reference block 16, finely adjusting the sliding table 13 in the optical axis direction, and observing the interference fringes, the object to be measured 10 can be measured. Find the position where the center of the sphere coincides with the focal point position 9. And at this time,
As shown in FIG. 3, a stopper 24 integral with the sliding base 13 comes into contact with the dial gauge 14, and the zero point of the dial gauge 14 is adjusted so that the pointer of the dial gauge 14 indicates zero.

Next, hold the handle 23 of the slide table 13 in your hand and move the slide table 13 to the left, and then touch the stopper 21 of the slide table 13 and the tip 26 of the micrometer 17.
Insert the reference block 16 between the handle 23 and then release the handle 23. Then, by the action of the spring of the slide table 13, the reference block 16 is lightly pressed between the stopper 21 and the tip 26, and the slide table 13 is moved exactly by the reference dimension a from the original position where the dial gauge 14 was zeroed. Move to the left and stop. In this state, the stopper 25 integral with the slide table 13 comes into contact with the dial gauge 15, and the zero point of the dial gauge 15 is adjusted so that the pointer of the dial gauge 15 indicates zero. Next, by operating the micrometer 17 and finely adjusting the sliding table 13 in the optical axis direction and observing the interference fringes, the position where the surface of the object to be measured 10 coincides with the focal position 9 is determined, and the Read the reading e of the pointer of the dial gauge 15. Then, the radius of curvature r of the object to be measured 10 in this case is r=
It can be immediately determined as a-e.

When the measurement of the first object to be measured 10 is completed, the object to be measured 10 is removed from the chuck 11, the reference block 16 is also removed, the slide table 13 is returned to its original position, and the second object to be measured is removed. Attach the object 10' to the chuck 11. and the second object to be measured 10
The optical axis is aligned, the micrometer 17 is operated, and the interference fringes are observed to determine the position where the center of the spherical surface coincides with the focal point position 9, and the reading f of the pointer of the dial gauge 14 at this time is read. Next, the sliding table 13 is moved manually, the reference block 16 is inserted, and the micrometer 17 is further operated to observe the interference fringes, so that the surface of the second object 10' is at the focal position. Find the position that matches 9,
At that time, read the reading e' of the pointer of the dial gauge 15. Then, the radius of curvature of the second measured object 10
r' can be immediately determined as r'=a-e'+f.

Hereinafter, similarly to the second object to be measured 10', the third object to be measured 10'
th, 4th... object to be measured 10'', 10...
The radius of curvature of ... is found in sequence.

In the above description, the object to be measured 10 has a concave spherical surface, but the present invention can also be applied to an object to be measured that has a convex spherical surface. Further, although the dial gauges 14 and 15 are used to measure the fine adjustment range, the present invention is not limited to the dial gauges 14 and 15, and other micrometers may be used.

As explained above, according to the present invention, the sliding table can be manually operated in one touch, and the operation time is short, so there is little time loss even when continuously measuring objects to be measured in mass production. This enables quick and efficient measurements. In addition, a reference block is used as the reference dimension, and when the center and surface of the spherical surface of the object to be measured are aligned with the focal position, the position reading is performed only within the fine adjustment range in the vicinity of each, allowing for small range and high precision. It is possible to use a micrometer such as a dial gauge, and furthermore, even when the radius of curvature to be measured is large, there is no cumulative error in the gauge, making it possible to perform precise measurements on the order of, for example, 0.001 mm. In addition, because of the above characteristics, the radius of curvature measurement using a laser interferometer, which conventionally required a long time, can be carried out in an extremely short time and accurately without using an expensive measurement mechanism. Significant efficiency improvement can be achieved in continuous measurement.

[Brief explanation of drawings]

Fig. 1 is a principle diagram of curvature radius measurement using a laser interferometer, Fig. 2 is an overall side view showing an embodiment of the apparatus used in the present invention, Fig. 3 is a schematic plan view of Fig. 2,
FIG. 4 is a side view illustrating the operation of FIG. 2. 6... Laser interferometer body, 8... Optical axis, 9...
...Focus position, 10...Object to be measured, 13...Sliding table, 14, 15...Dial gauge (micrometer),
16...Reference block.

Claims (1)

[Claims] 1. Move the object to be measured on the sliding table along the optical axis of the laser interferometer, and align the surface of the object with the position where the center of the spherical surface of the object coincides with the focal position of the reference spherical lens of the laser interferometer. The method detects a position that coincides with the focal position and measures the spherical curvature of the measured object based on the moving distance of the measured object in the optical axis direction between the two positions. By aligning the center with the focal position of the reference spherical lens of the laser interferometer and then using a reference block having a reference width corresponding to the reference radius of curvature of the object to be measured, the object to be measured is aligned with the reference spherical lens of the laser interferometer. The slide table is moved by the reference width toward the lens, and then the spherical surface of the object to be measured is aligned with the focal position of the reference spherical lens of the laser interferometer using the fine adjustment means to adjust the direction of the optical axis of the object to be measured. A method for measuring the radius of curvature of a spherical surface, characterized in that the distance traveled is determined.