CN101408405B - Optical aspheric measuring system and its platform - Google Patents

Abstract

The optical aspheric surface measurement system of the present invention comprises a measurement bracket, an interference optical path system and an optical aspheric surface measurement platform. The optical aspheric surface measurement platform comprises a yaw rotation mechanism and a radius adjustment mechanism. The yaw rotation mechanism is used to provide a yaw motion during measurement so that the interference optical path system can scan the entire curved surface of the object to be measured. The radius adjustment mechanism is used to adjust the spherical center position of the object to be measured so as to coincide with the center position of the yaw rotation mechanism.

Description

Optical aspheric measuring system and its platform

technical field

The present invention relates to a measurement system, and in particular to an optical aspheric surface measurement system.

Background technique

In the measurement of aspherical lenses or mold cores, the conventional technology is to measure the surface shape and roughness by contact, and the most criticized one is the scratches produced by the probe contact measurement. Scratches on the mold core must be repaired again with a processing machine; and if the lens is scratched, it cannot be used and must be scrapped. Therefore, most of the methods are random inspections, supplemented by QC methods to estimate the pass rate , It is impossible to do a full inspection of the product. This is a waste of time and an increase in potential risks for lens or mold core manufacturers.

The problems caused by contact measurement can be overcome by optical interferometry. Optical interferometry is widely used in plane measurement due to its advantages of fast, high precision and non-destructive detection. However, when measuring topography with high surface slopes such as spherical or aspherical surfaces, it cannot be measured due to the limitation of the light collection angle. This is one of the important problems to be overcome when applying light interference technology to spherical or aspherical surfaces.

Regarding the measurement of optical interference technology applied to spherical or aspheric surfaces, US Patent 2006/0290942 discloses that a measuring probe that can be used for deflection and left and right movement can be used to achieve the purpose of measurement. on the rotating platform. Such a design is quite easy to measure a concave DUT, but to measure a protruding DUT, due to the increase of the swing stroke and the center of the swing axis on the body of the measuring head, the whole will become complicated and difficult. Design implementation, and relatively cost will be much higher.

The commercially available goniometer is usually used as a deflection mechanism, but its deflection angle and direction have fixed restrictions, and the various aspheric lenses on the market now become shorter and shorter as the lens becomes shorter. It is getting bigger and bigger, so that such a goniometer-based yaw mechanism cannot meet the measurement needs.

Contents of the invention

An embodiment of the optical aspheric measuring platform of the present invention includes a yaw rotation mechanism and a radius adjustment mechanism. The yaw rotation mechanism provides yaw movement during measurement, and enables the fixed measuring probe to measure the range of the curved surface between the two ends of the yaw diameter. The radius adjustment mechanism is used to adjust the coincidence between the position of the center of the object to be measured and the center position of the yaw rotation mechanism, and the radius adjustment mechanism is fixed on the yaw rotation mechanism.

The embodiment of the optical aspheric surface measurement system of the present invention includes a measurement bracket, an interference optical path system and an optical aspheric surface measurement platform. The interference optical path system includes a measuring probe for measuring the range of the curved surface between two ends of the yaw diameter of the yaw rotation mechanism. The measurement bracket is used to fix the optical aspheric surface measurement platform and the interference optical system, and to adjust the relative distance between the measurement probe and the object to be measured.

Description of drawings

Fig. 1 shows the specific embodiment of the optical aspheric measuring platform of the present invention;

Fig. 2 shows the specific embodiment of optical type aspheric measuring system of the present invention; And

FIG. 3 shows a specific embodiment of the interference optical path system of the optical aspheric surface measuring system of the present invention.

Detailed ways

FIG. 1 shows a specific embodiment of the optical aspheric surface measurement platform of the present invention. A spherical or aspheric object to be tested 101 is placed on the element lens holder 102, and its surface topography is measured with a fixed measuring probe. The element lens holder 102 is fixed on the radius adjustment mechanism 103 . If the curved surface of the object to be measured is measured by light interference technology, under the condition of fixing the probe, the object to be measured must be able to do yaw movement, so as to overcome the problem of being unable to measure due to the limitation of the receiving angle caused by the curved surface. The so-called deflection here refers to the rotation action of the object under test, and its maximum range can reach plus or minus 90 degrees. However, different objects to be tested have different radii of curvature, or their shapes may be protruding or concave, etc., all of which will make the center of the object to be tested not on the yaw axis. If the object under test is in an eccentric state, as the object under test rotates, the measurement surface will deviate from the original measurement position, resulting in out-of-focus situations. The radius adjustment mechanism 103 is used to adjust the center of the object to be tested up and down above the axis of the yaw, so that when measuring objects with different curved surfaces, the yaw curved surface can still be kept within a certain range to avoid out of focus situation occurs. The radius adjustment mechanism in Figure 1 is a translation platform that can be adjusted in the Z-axis direction. If a convex aspheric surface is measured, the translation platform needs to be adjusted upward; if a concave aspheric surface is measured, it must be adjusted downward. . At the same time, in order to reduce the time spent on correcting the position of the center of the circle when measuring objects to be tested with different curvature radii, a scale 104 can be added to the radius adjustment mechanism 103 .

The radius adjustment mechanism 103 is fixed on the yaw rotation mechanism 105, and the yaw rotation mechanism 105 makes the radius adjustment mechanism 103 yaw, thereby driving the yaw movement of the object to be tested. The yaw rotation mechanism 105 is a rotatable mechanism driven by a motor or a precision rotation stage (Rotation stage), which can cause the object to be measured to produce the yaw motion required for measurement, which makes it possible to measure any part of a spherical or aspheric surface get. Because the rotation is driven by the motor, the fixed measuring probe can be swept across the range of the curved surface within plus or minus 90 degrees. The motor can use a side-standing rotary motor, which can rotate 360 degrees, so there is no limit to the rotation angle; and the entire circle shape can be measured without disassembling and re-calibrating the object to be tested. In addition to the above-mentioned deviation in the Z-axis direction that needs to be corrected before measurement, the deviation of the object to be measured on the optical axis position of the measuring probe also needs to be corrected. The yaw rotation mechanism 105 can be fixed on the position correction mechanism 107 by a connecting structure (such as an L-shaped adapter plate 106 ). In this way, a relatively precise device (such as an X precision translation stage or an XY precision translation stage, etc.) can be used to align the circle center of the object to be measured on the optical axis of the measuring probe.

FIG. 2 shows a specific embodiment of the optical aspheric surface measurement system of the present invention. The optical aspheric measurement system includes an interference optical system 201 , an optical aspheric measurement platform 202 and a measurement bracket 204 , wherein the interference optical system 201 includes a measurement probe 203 . The optical path system 201 is erected on the measurement bracket 204, and its built-in linear slide rail can focus on the object to be measured in the direction of the Z axis.

FIG. 3 shows a specific embodiment of the interference optical path system of the optical aspheric surface measuring system of the present invention. The architecture of the interference optical system 201 is developed based on the Linnik optical path. Described interference optical path system 201 comprises spectroscope 301, CCD 302, helium-neon laser 303, full-wavelength light reducing mirror (Neutral Density Filter) 304, 50X objective lens 305, pinhole (Pin Hole) 306, the first condenser lens 307, aperture ( Stop) 308, a second condenser lens 309, two 10X objective lenses 310 and a reference curved surface 311. The interference optical system 201 generates interference fringes on the CCD, thereby measuring the surface topography of the object to be tested. The steps of operating the measurement system are as follows: place the object to be measured on the element lens holder 102 on the optical aspheric measuring platform 202, and fix the object to be measured; the optical axis of the interference optical path system 201 shall prevail , adjust the position correction mechanism 107 so that the center position of the object to be measured is covered by the optical axis; adjust the radius adjustment mechanism 103 so that the center position of the object to be measured coincides with the center position of the yaw rotation mechanism 105 ; Using the adjustment mechanism in the measurement bracket 204, adjust the focus of the interference optical system 201 on the object to be measured, and generate interference fringes, and then obtain the topography data of the center area of the object to be measured; adjust the The yaw rotation mechanism 105 rotates clockwise, allowing the interference optical system 201 to obtain the topography data of the edge region of the object to be measured; data.

The technical content and technical features of the present invention have been disclosed above, but those skilled in the art may still make various replacements and modifications based on the teaching and disclosure of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to those disclosed in the embodiments, but should include various replacements and modifications that do not depart from the present invention, and are covered by the appended claims.

Claims (15)

1. optical type aspherical measuring table is characterized in that comprising:

The beat rotating mechanism is used to provide the motion of the beat when measuring, so that fixation measuring probe energy measurement is to the curved surface scope between the beat diameter two ends;

The radius adjusting mechanism is fixed on the described beat rotating mechanism, is used to adjust the sphere center position of determinand and the center of described beat rotating mechanism coincides; And

Be fixed in the element lens mount on the described radius adjusting mechanism.

2. optical type aspherical measuring table according to claim 1, it is characterized in that further comprising the position correction mechanism and the connecting structure of one dimension or two dimension, the wherein said connecting structure described position correction mechanism that is used for locking makes determinand can do horizontal adjustment.

3. optical type aspherical measuring table according to claim 2 is characterized in that wherein said connecting structure comprises L type card extender.

4. optical type aspherical measuring table according to claim 2 is characterized in that wherein said position correction mechanism comprises the accurate translation stage of XY.

5. optical type aspherical measuring table according to claim 1 is characterized in that wherein said radius adjusting mechanism comprises the accurate translation stage of single shaft.

6. optical type aspherical measuring table according to claim 1 is characterized in that the side of wherein said radius adjusting mechanism further comprises rule, in order to reduce the eccentric correction time.

7. optical type aspherical measuring table according to claim 1 is characterized in that wherein said beat rotating mechanism comprises the motor of rotatable 360 degree, and described motor comprises edge-on rotation motor.

8. optical type aspherical measuring system is characterized in that comprising:

The optical type aspherical measuring table has the beat rotating mechanism, and wherein said optical type aspherical measuring table can be adjusted the sphere center position of determinand and the center of described beat rotating mechanism coincides;

The optical interference circuit system comprises measuring sonde, in order to the curved surface scope between the beat diameter two ends of measuring described beat rotating mechanism;

Measurement bracket in order to fixing described optical type aspherical measuring table and described optical interference circuit system, and is used to adjust the relative distance of described measuring sonde and determinand;

The radius adjusting mechanism is fixed on the described beat rotating mechanism, is used to adjust the center of the sphere center position of determinand to described beat rotating mechanism; And

Be fixed in the element lens mount on the described radius adjusting mechanism.

9. optical type aspherical measuring system according to claim 8, it is characterized in that wherein said optical type aspherical measuring table further comprises the position correction mechanism and the connecting structure of one dimension or two dimension, the wherein said connecting structure described position correction mechanism that is used for locking makes the sphere center position of described determinand be adjustable on the optical axis of described optical interference circuit system.

10. optical type aspherical measuring system according to claim 9 is characterized in that wherein said connecting structure comprises L type card extender.

11. optical type aspherical measuring system according to claim 9 is characterized in that wherein said position correction mechanism comprises the accurate translation stage of XY.

12. optical type aspherical measuring system according to claim 8 is characterized in that wherein said radius adjusting mechanism comprises the accurate translation stage of single shaft.

13. optical type aspherical measuring system according to claim 8 is characterized in that the side of wherein said radius adjusting mechanism further comprises rule, in order to reduce the eccentric correction time.

14. optical type aspherical measuring system according to claim 8 is characterized in that the used motor of wherein said beat rotating mechanism comprises edge-on rotation motor, and rotatable 360 degree of described motor.

15. optical type aspherical measuring system according to claim 8 is characterized in that the framework of wherein said optical interference circuit system comprises the interference of light framework that is developed based on the Linnik light path.

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