METHOD AND SYSTEM FOR PROVIDING A HIGH DEFINITION TRIANGULATION SYSTEM

• US 20100277717A1
• Filed: 10/30/2009
• Published: 11/04/2010
• Est. Priority Date: 11/07/2006
• Status: Abandoned Application

• Current Assignee: Rudolph Technologies Incorporated (Onto Innovation Inc.)
• Original Assignee: Rudolph Technologies Incorporated (Onto Innovation Inc.)
• Inventors: Stern, Howard, Lawrence, Murray, Drannbauer, James, Krichever, Mark
• Application Number:
  US12/609,175
• Publication Number:
  US 20100277717A1
• Time in Patent Office: Days
• US Class Current: 356/51
• CPC Class Codes: G01B 11/0608 Height gauges

Abstract

A triangulation system including a laser beam, optics focusing the laser beam on an object, a light detection unit detecting light reflected from the object due to impingement of the beam on the object, and an arrangement for determining, based on the detected light, object feature dimensions. The wavelength of the laser beam may be shorter than of infrared radiation, which allows for a reduced spot size without significant loss of depth of field. So as to reduce aberrations or a sensitivity to aberrations due to the shortened wavelength, the system may include (i) a polarization dependent coating matching the index of refraction of an element of the light detection unit to that of air for a range of angles, (ii) tilted projection optics, (iii) a prism wavefront corrector, and/or (iv) a positioning assembly, which provides for increased precision in positioning the laser diode with respect to a collimator lens.

Claims

1. A method for providing a limited range of signals to be handled by a light detecting unit of a laser beam triangulation system used to inspect a highly specular object, comprising:

producing a laser beam having a wavelength shorter than infrared radiation wavelengths; and

focusing the laser beam to impinge on the object, the impinged light being reflected as the signals to the light detecting unit.

2. The method of claim 1, wherein the wavelength is shorter than 830 nm.

3. The method of claim 1, wherein the wavelength the wavelength is centered in a range of 380 to 660 nm.

4. The method of claim 1, wherein the wavelength the wavelength is centered in a range of 380 to 570 nm.

5. The method of claim 1, wherein the wavelength the wavelength is centered at 535 nm.

6. The method of claim 1, wherein the wavelength the wavelength corresponds to that of visible light.

7. The method of claim 1, wherein the wavelength the wavelength corresponds to at least one of red light, green light, blue light, and violet light.

8. The method of claim 1, wherein the wavelength is shorter than that of visible light.

9. A method for detecting features of a target object using a triangulation system, comprising:

producing a laser beam having a wavelength less than that of infrared radiation;

focusing the laser beam on an object;

detecting radiation reflected from the object due to impingement of the laser beam on the object;

based on the detecting, determining at least one dimension of at least one feature of the object; and

using the laser beam to produce a spot size that is equal to one which would be produced by a laser beam having an approximately infrared radiation wavelength, the spot size being produced by increasing an F# of optics of the triangulation system.

10. The method of claim 9, wherein the triangulation system is a laser beam scanning triangulation system.

11. The method of claim 9, wherein the wavelength is shorter than 830 nm.

12. The method of claim 9, wherein the wavelength is centered in a range of 380 to 660 nm.

13. The method of claim 9, wherein the wavelength is centered in a range of 380 to 570 nm.

14. The method of claim 9, wherein the wavelength is centered at 535 nm.

15. The method of claim 9, wherein the wavelength corresponds to that of visible light.

16. The method of claim 9, wherein the wavelength corresponds to at least one of red light, green light, blue light, and violet light.

17. The method of claim 9, wherein the wavelength is shorter than that of visible light.

18. A radiation beam scanning triangulation method, comprising:

producing a radiation beam;

focusing the radiation on an object;

reducing aberrations that cause field tilt and curvature;

detecting radiation reflected from the object due to impingement of the radiation beam on the object; and

determining, based on the detected radiation, at least one dimension of at least one feature of the object.

19. The method of claim 18, wherein the aberrations are reduced via a corrective component that includes at least one of tilted projection optics and a prism wavefront corrector.

20. The method of claim 18, wherein a wavelength of the radiation beam is shorter than 830 nm.