VCSEL based low coherence emitter for confocal 3D scanner

• US 10,148,066 B2
• Filed: 04/18/2017
• Issued: 12/04/2018
• 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): Park, Kinam
• Application Number:
  US15/490,531
• Publication Number:
  US 20170222404A1
• Time in Patent Office: 595 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. A light source for illuminating an optical system, comprising:

an array of VCSELs operatively connectable to a power source; and

a homogenizing lens array comprising a plurality of homogenizing lenses, each VCSEL emitter having a respective homogenizing lens of the plurality in registry therewith, the homogenizing lens array and array of VCSELs configured to generate a far field homogenized pattern of overlapping light beams at a spot generator microlens array.

2. The light source as in claim 1, wherein the array of VCSELs comprises a single substrate and a common light emitting material in order to provide similar overlapping wavelengths for each laser of the array, and wherein each laser comprises a full width half maximum wavelength bandwidth overlapping with at least about 50% of a full width half maximum of each other laser of the array.

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

4. The light source as in claim 3, wherein the array of VCSELs comprises a plurality of VCSELs, wherein one or more wavelengths of each VCSEL of the plurality of VCSELs overlaps with one or more wavelengths of other VCSELs of the plurality of VCSELs.

5. The light source as in claim 4, wherein said each of the plurality of VCSELs comprises a full width half maximum bandwidth of wavelengths overlapping with full width half maximum of wavelengths of other VCSELs of the plurality of VCSELs.

6. The light source as in claim 5, wherein said each of the plurality of VCSELs 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 VCSELs of the plurality.

7. The light source as in claim 3, wherein wavelengths of said each of the plurality of VCSELs does not overlap with wavelengths of other VCSELs of the plurality.

8. The light source as in claim 1, wherein the array of VCSELs comprises a plurality of VCSELs to emit a plurality of light beams and wherein the homogenizing lens array comprises a plurality of homogenizing microlenses aligned with the plurality of VCSELs to homogenize an energy distribution profile at the spot generator microlens array.

9. The light source as in claim 8, 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.

10. The light source as in claim 8, 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.

11. The light source as in claim 10, wherein the maximum value and the minimum value are within about 10% of the mean value of the energy profile distribution.

12. The light source as in claim 1, wherein each of the plurality of VCSELs comprises a similar polarization angle to within about 10% of other VCSELs of the plurality.

13. The light source as in claim 12, wherein the substantially similar polarization angle is within about 5% of other VCSELs of the plurality.

14. The light source as in claim 1, further comprising:

circuitry coupled to the plurality of VCSELs, wherein the circuitry comprises instructions to generate the plurality of light beams at predetermined time intervals.

15. A intraoral scanning system, comprising:

a handheld intraoral scanner;

an optical system within the intraoral scanner; and

a light source within the scanner that produces an array of light beams, the light source including;

an array of VCSELs operatively connectable to a power source; and

a homogenizing lens array comprising a plurality of homogenizing lenses, each VCSEL emitter having a respective homogenizing lens of the plurality in registry therewith, the homogenizing lens array and array of VCSELs configured to generate a far field homogenized pattern of overlapping light beams at a spot generator microlens array.

16. The intraoral scanning system of claim 15, further comprising:

a sensor array including a matrix of sensing elements for measuring a characteristic of reflected light of the array of light beams.

17. The intraoral scanning system of claim 16, wherein the characteristic is intensity.

18. The intraoral scanning system of claim 16, further comprising a processing unit configured to reconstruct the surface topography of the intraoral cavity based on the measured intensity of returning light of the array of light beams.

19. The intraoral scanning system of claim 15, wherein a plurality of spot generating lenses is arranged in a the spot generator microlens array and wherein the array of VCSELs and the spot generator microlens array are arranged to provide an extended light source and inhibit Talbot noise.

20. The intraoral scanning system of claim 15, wherein the array of VCSELs comprises a plurality of VCSELs, wherein one or more wavelengths of each VCSEL of the plurality of VCSELs overlaps with one or more wavelengths of other VCSELs of the plurality of VCSELs.