Athermal Optical Assembly

Patent metadata

Field	Value
Publication number	US-2020064584-A1
Application number	US-201615769916-A
Country	US
Kind code	A1
Filing date	Oct 21, 2016
Priority date	Oct 22, 2015
Publication date	Feb 27, 2020
Grant date	—

Abstract

This disclosure describes optical assemblies that generate output with substantial stability over a wide variation in temperature. The optical assemblies can be integrated, for example, as part of array generators arranged to project an array or other pattern of dots onto an object or projection plane.

First claim

1 . A hybrid optical assembly comprising:
a first transmissive substrate; a first aspherical lens on a first side of the first transmissive substrate; a second hybrid diffractive/refractive lens on a second side of the first transmissive substrate; a second transmissive substrate separated from the first transmissive substrate; a third aspherical lens on a first side of the second transmissive substrate; and a fourth aspherical lens on a second side of the second transmissive substrate; wherein the third aspherical lenses lens faces the second hybrid diffractive/refractive lens, and wherein the output of the hybrid optical assembly exhibits substantial stability over a temperature range of 20° C.-100° C.

2 . The hybrid optical assembly of claim 1 wherein the first and second transmissive substrates are separated from one another by a distance in a range of 4 mm-10 mm.

3 . The hybrid optical assembly of claim 1 wherein the first and second transmissive substrates are composed of clear borosilicate glass and the first, second, third and fourth lenses are composed of epoxy.

4 . An optical pattern generator comprising:
an array of light emitting elements; and a hybrid optical assembly according to claim 1 , wherein the array of light emitting elements is disposed such that light generated by the light emitting elements passes through the fourth lens, the third lens, the second lens and the first lens of the hybrid optical assembly, in that order, so as to project a pattern of optical dots corresponding to the arrangement of the light emitting elements.

5 . The optical array generator of claim 4 wherein the light emitting elements are VCSELs.

6 . A method of generating a pattern of optical dots, the method comprising:
emitting light from a plurality of light emitting elements arranged in an array or other pattern; passing the emitted light through a hybrid optical assembly comprising three aspherical lenses and a hybrid diffractive/refractive lens; and projecting the light that passed through the hybrid optical assembly onto an object or plane, wherein the projected light forms a pattern of dots.

7 . (Currently amended The method of claim 6 including passing the emitted light through the hybrid optical assembly.

8 . The hybrid optical assembly according to claim 1 , wherein the first aspheric lens has a focal-length-normalized curvature of 9.21, the second hybrid diffractive/refractive lens has a focal-length-normalized curvature of 2.85, the third aspheric lens has a focal-length-normalized curvature of 0.34, and the fourth aspheric lens has a focal-length-normalized curvature of 0.78.

9 . The hybrid optical assembly according to claim 1 , wherein the first aspheric lens, the second hybrid diffractive/refractive lens, the third aspheric lens, and the fourth aspheric lens have focal-length-normalized diameters of 0.49, 0.49, 0.35, and 0.29, respectively.

10 . The hybrid optical assembly according to claim 1 , wherein the first aspheric lens, the second hybrid diffractive/refractive lens, the third aspheric lens, and the fourth aspheric lens have focal-length-normalized thicknesses of 0.0044, 1.048, 0.067, and 0.067, respectively.

11 . The hybrid optical assembly according to claim 8 having an aspect ratio of 0.356.

12 . The hybrid optical assembly according to claim 8 , the first, third and fourth aspherical lenses have the following coefficients, respectively:

1 st aspheric
3 rd aspheric
4 th aspheric

Coefficient (r)
lens
lens
lens

Fourth-order
−0.103
0.114
0.382

Sixth-order
0
2.4032
3.544

Eighth-order
0
−41.19
−62.281

Tenth-order
0
324.92
523.773

Twelfth-order
0
−1203.11
−1930.264

Fourteenth-order
0
1694.44
2348.243

and wherein the second hybrid diffractive/refractive lens has the following coefficients:

2 nd hybrid

diffractive/refractive

Coefficient (ρ)
lens

Aspheric Fourth-order
−0.115

Aspheric Sixth-order
−0.859

Aspheric Eighth-order
5.705

Aspheric Tenth-order
−17.849

Aspheric Twelfth-order
28.092

Aspheric Fourteenth-order
−17.554

Diffractive-phase Second-order
−525.287

Diffractive-phase Fourth-order
71.546

Diffractive-phase Sixth-order
−30.983

13 . The hybrid optical assembly according to claim 8 having an aspect ratio of 0.224.

14 . The hybrid optical assembly according to claim 8 , wherein the first, third and fourth aspheric lenses have the following coefficients, respectively:

Assignees

• Heptagon Micro Optics Pte Ltd

Inventors

• Engelhardt Kai
• Rossi Markus

Classifications

• G02B13/18

  with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration {(G02B13/002 takes precedence)} · CPC title

• G02B7/008 Primary

  with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation · CPC title

• G02B7/028 Primary

  with means for compensating for changes in temperature or for controlling the temperature; thermal stabilisation · CPC title

• G02B5/1876

  Diffractive Fresnel lenses; Zone plates; Kinoforms (G02B5/1842, G02B5/1847 take precedence; optical systems having diffractive correction means G02B27/0037; Fresnel lenses operating by refraction G02B3/08) · CPC title

• G02B27/0037

  with diffracting elements (G02B27/0056 takes precedence; holographic optical elements G02B5/32; zone systems G02B5/1876) · CPC title