VCSEL based low coherence emitter for confocal 3D scanner

• US 9,660,418 B2
• Filed: 08/27/2014
• Issued: 05/23/2017
• Est. Priority Date: 08/27/2014
• Status: Active Grant

• Current Assignee: Align Technology Incorporated
• Original Assignee: Align Technology Incorporated
• Inventors: Atiya, Yossef, Verker, Tal
• Primary Examiner(s): STAFIRA, MICHAEL PATRICK
• Application Number:
  US14/470,832
• Publication Number:
  US 20160064898A1
• Time in Patent Office: 1,000 Days
• CPC Class Codes: A61C 9/0053 Optical means or methods, e.g. scanning the teeth by a laser or light beam
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: G01B 11/0608 Height gauges
• CPC Class Codes: G01B 11/24 for measuring contours or curvatures
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G02B 27/0961 Lens arrays lens arrays per se G02B3/0006
• CPC Class Codes: H01S 2301/02 ASE (amplified spontaneous emission), noise; Reduction thereof
• CPC Class Codes: H01S 2301/04 Gain spectral shaping, flattening
• CPC Class Codes: H01S 2301/206 Top hat profile
• CPC Class Codes: H01S 5/005 Optical components external to the laser cavity, specially adapted therefor, e.g. for homogenisation or merging of the beams or for manipulating laser pulses, e.g. pulse shaping H01S5/026, H01S5/18388 take precedence
• CPC Class Codes: H01S 5/0071 for beam steering, e.g. using a mirror outside the cavity to change the beam direction
• CPC Class Codes: H01S 5/06817 Noise reduction
• CPC Class Codes: H01S 5/183 having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
• CPC Class Codes: H01S 5/42 Arrays of surface emitting lasers
• CPC Class Codes: H01S 5/423 having a vertical cavity

Abstract

Methods and apparatus for measuring objects comprise a plurality of light sources to generate a plurality of light beams directed toward a spot generator array comprising a plurality of spot generating lenses. The plurality of light sources is separated from the spot generator array with a separation distance sufficient to overlap the plurality of light beams at each of the spot generating lenses. The overlap of each of the beams at each of the spot generating lenses provides smoothing of the energy profile of the light energy incident on the spot generating lenses. The spot generator array generates focused spots comprising overlapping focused beams. The overlapping beams may comprise overlapping beams of a vertical cavity surface emitting laser (VCSEL) array, and the overlapping focused beams can decrease optical artifacts.

Claims

1. An apparatus to measure an object, the apparatus comprising:

a plurality of light sources arranged to generate a plurality of light beams; and

a plurality of spot generating lenses to focus the plurality of beams to a plurality of focused spots, each of the plurality of focused spots comprising a focused portion of each of the plurality of light beams, said focused portion of each of the plurality of beams overlapping with other focused portions of other beams in order to define said each of the plurality of focused spots and inhibit noise, wherein the plurality of spot generating lenses is separated from the plurality of light sources with a separation distance sufficient to overlap the plurality of light beams at each of the spot generating lenses.

2. An apparatus as in claim 1, wherein the apparatus comprises a scanning confocal apparatus to measure topography of the object in response to scanning of said each of the plurality of focused spots.

3. An apparatus as in claim 1, wherein said each of the plurality of lenses comprises a focal length, and said each of the plurality of light sources comprises a spacing distance from adjacent sources of the plurality of light sources and wherein said separation distance, said focal length and said spacing distance are arranged to overlap said focused portion of each of the plurality of beams with other focused portions of other beams near the focal length in order to inhibit noise.

4. An apparatus as in claim 1, wherein the plurality of light sources is arranged in a light source array and the plurality of spot generating lenses is arranged in a spot generator microlens array and wherein the light source array and the spot generator microlens array are arranged to provide an extended light source and inhibit Talbot noise.

5. An apparatus as in claim 1, wherein one or more wavelengths of said each of the plurality of light sources overlaps with one or more wavelengths of other light sources of the plurality of light sources.

6. An apparatus as in claim 5, wherein said each of the plurality of light sources comprises a full width half maximum bandwidth of wavelengths overlapping with full width half maximum of wavelengths of other light sources of the plurality of light sources.

7. An apparatus as in claim 6, wherein said each of the plurality of light sources comprises a full width half maximum bandwidth of no more than about 2 nm overlapping with said full width half maximum bandwidth of said other light sources of the plurality.

8. An apparatus as in claim 1, wherein wavelengths of said each of the plurality of light sources does not overlap with wavelengths of other light sources of the plurality.

9. An apparatus as in claim 1, the apparatus further comprising:

a plurality of homogenizing microlenses aligned with the plurality of light sources to homogenize an energy distribution profile of said each of the plurality of light beams at the microlens array.

10. An apparatus as in claim 9, wherein each of the plurality of homogenizing microlenses comprises an optical surface shaped to homogenize the energy distribution profile, the optical surface comprising one or more of an aspheric refractive optical surface, a diffractive optical surface or a holographic optical surface.

11. An apparatus as in claim 9, wherein the energy distribution profile comprises a substantially uniform energy profile comprising a maximum value and a minimum value within about 25% of a mean value of the energy profile distribution provided to the plurality of spot generating lenses.

12. An apparatus as in claim 11, wherein the maximum value and the minimum value are within about 10% of the mean value of the energy profile distribution.

13. An apparatus as in claim 1, wherein each light source of the plurality comprises a similar polarization angle to within about 10% of other light sources of the plurality.

14. An apparatus as in claim 1, further comprising:

a detector array; and

circuitry coupled to the plurality of light sources and the detector array, wherein the circuitry comprises instructions to generate the plurality of light beams at predetermined time intervals.

15. A method of measuring an object, the method comprising:

generating a plurality of light beams; and

focusing the plurality of light beams to a plurality of focused spots with a plurality of spot generating lenses separated from the plurality of light sources with a separation distance sufficient to overlap the plurality of light beams at each of the spot generating lenses, wherein each of the plurality of focused spots comprises a focused portion of each of the plurality of light beams, said focused portion of each of the plurality of beams overlapping with other focused portions of other beams in order to define said each of the plurality of focused spots and inhibit noise.

16. A method as in claim 15, wherein said each of the plurality of lenses comprises a focal length, said each of the plurality of light sources comprises a spacing distance from adjacent sources of the plurality of light sources and wherein said separation distance, said focal length and said spacing distance are arranged to overlap said focused portion of each of the plurality of beams with other focused portions of other beams near the focal length in order to inhibit noise.