Coaxial distance measurement via folding of triangulation sensor optics path

• US 10,112,258 B2
• Filed: 03/30/2012
• Issued: 10/30/2018
• Est. Priority Date: 03/30/2012
• Status: Active Grant

• Current Assignee: View Incorporated
• Original Assignee: View Incorporated
• Inventors: Baxter, Bruce, Mullins, Dennis
• Primary Examiner(s): Chou, Jimmy
• Application Number:
  US13/436,387
• Publication Number:
  US 20130256285A1
• Time in Patent Office: 2,405 Days
• Field of Search: 21912167, 21912168, 21912183, 21912172, 356623, 356631, 356602, 356 313, 356 301, 356 31
• CPC Class Codes: B23K 26/048 by controlling the distance between laser head and workpiece
• CPC Class Codes: B23K 26/364 for making a groove or trench, e.g. for scribing a break initiation groove
• CPC Class Codes: G01S 17/48 Active triangulation systems, i.e. using the transmission and reflection of electromagnetic waves other than radio waves
• CPC Class Codes: G01S 7/481 Constructional features, e.g. arrangements of optical elements

Abstract

This disclosure provides apparatus and methods for scribing a substrate. In one aspect, an apparatus includes optics for focusing a scribe beam onto a substrate and a beam focus adjustment mechanism for adjusting the optics. A triangulation-based distance sensor determines a distance between the triangulation-based distance sensor and the substrate, with the triangulation-based distance sensor being positioned at a location offset from the scribe beam. Reflecting elements are positioned to reflect an incident beam from the triangulation-based distance sensor'"'"'s source to the substrate and then back to the triangulation-based distance sensor'"'"'s detector. The beam focus adjustment mechanism adjusts the optics based on the distance between the triangulation-based distance sensor and the substrate so that the scribe beam is focused at a desired position on the substrate.

Claims

1. An apparatus configured for scribing an optical coating on a transparent substrate having a first side and a second side with the optical coating disposed on one of the first side and the second side, the apparatus comprising:

a stage having one side and an opposing side, and an aperture through the stage;

a scribe laser having a focus lens, a scribe laser beam from the scribe laser, wherein the scribe laser is located on one side of the stage and the transparent substrate is located to the opposing side of the stage, wherein the scribe laser beam is configured to pass through the aperture in the stage to impinge upon the transparent substrate substantially orthogonally, and wherein the scribe laser beam is further configured to ablate the optical coating;

a first mirror attached to the opposing side of the stage;

a second mirror attached to the opposing side of the stage; and

a triangulation-based distance sensor attached to the opposing side of the stage and comprising a triangulation laser and a detector, the triangulation-based distance sensor configured such that a triangulation laser beam from the triangulation laser is emitted substantially parallel to the transparent substrate, impinges on and is reflected from the first mirror to impinge on the transparent substrate at a first acute angle of incidence measured with respect to a normal to the transparent substrate, is reflected from the transparent substrate at a second acute angle measured with respect to the normal to the transparent substrate to the second mirror, and is reflected from the second mirror to the detector,

wherein the apparatus determines a distance between the one of a first side and a second side of the transparent substrate with the optical coating and the focus lens of the scribe laser based on a measured position of the reflected triangulation laser beam on the detector, and

wherein a span of the first acute angle and the second acute angle is a third acute angle which is bisected by the scribe laser beam passing through the aperture in the stage.

2. The apparatus of claim 1, wherein the triangulation-based distance sensor and the scribe laser are located on a same side of the transparent substrate with the optical coating.

3. The apparatus of claim 1, wherein the triangulation laser beam is reflected to the detector in a direction substantially parallel to the transparent substrate.

4. The apparatus of claim 1, wherein the scribe laser has an output power of greater than 500 mW for the scribe laser beam.

5. The apparatus of claim 1, wherein the scribe laser beam and the triangulation laser beam have different wavelengths.

6. The apparatus of claim 1, wherein the triangulation laser beam is configured to intersect the scribe laser beam at a nominal focal plane.

7. The apparatus of claim 1, wherein the triangulation-based distance sensor is configured to determine a position of an interface between the optical coating and the transparent substrate.

8. The apparatus of claim 1, wherein the focus lens is configured to adjust a focal point of the scribe laser beam to an interface between the optical coating and the transparent substrate.

9. The apparatus of claim 7,

further comprising a processor, wherein the processor is configured to position the focus lens to adjust a focal point of the scribe laser beam to the interface determined by the triangulation-based distance sensor.

10. The apparatus of claim 1, wherein the detector is a charge-coupled device.

11. The apparatus of claim 1, wherein the third acute angle formed between incidence and reflection of the triangulation laser beam at the transparent substrate is between about 5 degrees and about 45 degrees.

12. The apparatus of claim 1, wherein the third acute angle formed between incidence and reflection of the triangulation laser beam at the transparent substrate is between about 8 degrees and about 20 degrees.

13. The apparatus of claim 1, wherein the normal to the transparent substrate is coaxial to an optical path of the scribe laser beam.

14. The apparatus of claim 1,

wherein the triangulation-based distance sensor is configured to measure a distance between the triangulation-based distance sensor and the optical coating of the transparent substrate,

and wherein the distance is measured along an axis that is a coaxial to an optical path of the scribe laser beam.

15. The apparatus of claim 14,

wherein the distance is measured to a point at the optical coating,

and wherein the point is located within plus or minus 5 millimeters from an intersection of the scribe laser beam with the optical coating.

16. The apparatus of claim 1, wherein the scribe laser beam is configured to impinge upon the optical coating from the second side of the transparent substrate.

17. The apparatus of claim 1, wherein the scribe laser beam is configured to impinge upon the optical coating from the first side of the transparent substrate.

18. The apparatus of claim 1, wherein the scribe laser is configured to provide the scribe laser beam with a depth of focus of ±

100 μ

m or less.

19. The apparatus of claim 1, wherein the scribe laser is configured to provide the scribe laser beam with a depth of focus of ±

50 μ

m or less.

20. The apparatus of claim 1, wherein the triangulation-based distance sensor and the scribe laser are located, during operation, on an opposite side of the transparent substrate from the optical coating.