METHOD AND APPARATUS FOR DETECTING DEFECT IN TRANSPARENT BODY

• US 20170307546A1
• Filed: 03/29/2017
• Published: 10/26/2017
• Est. Priority Date: 04/26/2016
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: FUKUDA, Shinji
• Granted Patent: US 9,885,673 B2
• Time in Patent Office: Days
• CPC Class Codes: G01M 11/0278 Detecting defects of the object to be tested, e.g. scratches or dust investigating the presence of flaws or contamination on materials by optical means G01N21/88
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: G01N 21/8806 Specially adapted optical and illumination features
• CPC Class Codes: G01N 21/958 Inspecting transparent materials or objects, e.g. windscreens for conveyed flat sheet or rod G01N21/896

Abstract

A quantitative, high-sensitivity examination of defects in a transparent product is realized, using a low-cost and space-saving optical dimension measuring apparatus to carry out measurement in a non-contact manner to avoid damaging the object of inspection and to avoid sensory examination. A transparent body to be examined is disposed between a light emitting unit and a light-receiving unit arranged opposite each other. A change in an optical path caused by a defect in the transparent body is detected based on a change in a light ray emitted from the light emitting unit and being incident on the light-receiving unit after passing through the transparent body and a light-blocking object disposed between the transparent body and the light-receiving unit.

Claims

1. A method for detecting a defect in a transparent body, the method comprising:

disposing a transparent body to be examined between a light emitting unit and a light-receiving unit arranged opposite each other, a light-blocking object being arranged between the transparent body and the light-receiving unit; and

detecting a change in an optical path caused by a defect in the transparent body based on a change in a light ray emitted from the light emitting unit and being incident on the light-receiving unit after passing through the transparent body and the light-blocking object.

2. The method according to claim 1, wherein the light emitting unit scans a laser beam in a measurement direction and the light-receiving unit focuses and detects the scanned laser beam after passing through the transparent body and the light-blocking object.

3. The method according to claim 1, wherein the light emitting unit emits a linear light ray and the light-receiving unit receives the linear light ray after passing through the transparent body and the light-blocking object.

4. The method according to claim 1, wherein the light-blocking object is a pin gage that is moved in a measurement direction.

5. The method according to claim 2, wherein the light-blocking object is a pin gage that is moved in the measurement direction.

6. The method according to claim 3, wherein the light-blocking object is a pin gage that is moved in a measurement direction.

7. The method according to claim 1, wherein the light-blocking object is a fixed optical lattice having light and dark areas distributed at intervals smaller than a defect in the transparent body.

8. The method according to claim 2, wherein the light-blocking object is a fixed optical lattice having light and dark areas distributed at intervals smaller than a defect in the transparent body.

9. The method according to claim 3, wherein the light-blocking object is a fixed optical lattice having light and dark areas distributed at intervals smaller than a defect in the transparent body.

10. The method according to claim 1, wherein the transparent body is a lens.

11. A device for detecting a defect in a transparent body, the device comprising:

a light emitting unit;

a light-receiving unit disposed opposite from the light emitting unit;

a light-blocking object disposed between the light emitting unit and the light-receiving unit; and

a controller configured to detect a change in an optical path caused by a defect in a transparent body to be examined based on a change in a light ray emitted from the light emitting unit and being incident on the light-receiving unit after passing through the transparent body and the light-blocking object, wherein

the device is configured to arrange the transparent body between the light emitting unit and the light-blocking object.

12. The device according to claim 11, wherein

the light emitting unit includes a scanner that scans a laser beam in a measurement direction;

and

the light-receiving unit includes a condenser that condenses the scanned laser beam after passing through the transparent body and the light-blocking object.

13. The device according to claim 11, wherein

the light emitting unit includes an emitter that emits a linear light ray;

and

the light-receiving unit includes a receiver that receives the linear light ray after passing through the transparent body and the light-blocking object.

14. The device according to claim 11, wherein the light-blocking object is a pin gage that moves in a measurement direction.

15. The device according to claim 12, wherein the light-blocking object is a pin gage that moves in the measurement direction.

16. The device according to claim 13, wherein the light-blocking object is a pin gage that moves in a measurement direction.

17. The device according to claim 11, wherein the light-blocking object is a fixed optical lattice having light and dark areas distributed at intervals smaller than a defect in the transparent body.

18. The device according to claim 12, wherein the light-blocking object is a fixed optical lattice having light and dark areas distributed at intervals smaller than a defect in the transparent body.

19. The device according to claim 13, wherein the light-blocking object is a fixed optical lattice having light and dark areas distributed at intervals smaller than a defect in the transparent body.

20. The device according to claim 11, wherein the device includes an optical element having a shape corresponding to the shape of a lens when the transparent body is the lens.