Lidar scanning with expanded scan angle
In described examples of a system for outputting a patterned light beam, the system includes: an illumination source; a positive optical element positioned to receive light from the illumination source and to output converging light; a reflective element positioned to receive the converging light from the positive optical element, the reflective element configured to reflect the converging light to form a scan beam; and a negative optical element to receive the scan beam from the reflective element, the negative optical element configured to output the scan beam to a field of view.
1. A system comprising:
an illumination source configured to generate light;
an optical modulator;
a positive optical element configured to receive the light from the illumination source and to focus the light towards the optical modulator as converging light; and
a negative optical element;
the optical modulator configured to reflect the converging light, to form a scan beam directed towards the negative optical element; and
the negative optical element configured to receive the scan beam from the optical modulator, the negative optical element configured to output the scan beam to scan a scanning field of view, wherein the negative optical element is configured to increase the scanning field of view.
2. The system of claim 1 , wherein the optical modulator is an analog MEMS mirror.
3. The system of claim 1 , wherein the optical modulator is a phase spatial light modulator (PSLM).
4. The system of claim 3 , wherein the PSLM is a digital micromirror device.
5. The system of claim 1 , wherein the optical modulator is a liquid crystal on silicon (LCoS) reflective device.
6. The system of claim 1 , wherein the optical modulator is a digital micromirror device (DMD).
7. The system of claim 1 , wherein the optical modulator is a digital micromirror device (DMD) comprising an array of micromirrors configured to display diffraction patterns that create at least one patterned light beam.
8. The system of claim 7 , wherein the diffraction patterns include corrected diffraction patterns corrected to compensate for distortion.
9. The system of claim 8 , wherein the corrected diffraction patterns are determined by computing a two dimensional polynomial.
10. The system of claim 9 , wherein computing the two dimensional polynomial includes computing:
H ( x,y )= A exp( j φ( x,y )),
where H(x, y) is the corrected diffraction pattern in two dimensions, and
jφ(x, y) is a correction factor in two dimensions for each micromirror at a position x, y.
11. The system of claim 8 , wherein the corrected diffraction patterns include diffraction patterns corrected to compensate for astigmatism in the system.
12. The system of claim 8 , further comprising a processor configured to provide diffraction patterns for display using the digital micromirror device and to control the illumination source.
13. The system of claim 12 , further comprising a diffraction pattern memory configured to store diffraction patterns for display using the digital micromirror device.
14. The system of claim 12 , wherein the processor is configured to perform a real time diffraction pattern-generating algorithm, comprising a correction algorithm for outputting corrected diffraction pattern data to the digital micromirror device to display diffraction patterns.
15. The system of claim 1 , wherein the positive optical element and the negative optical element together form one of a reverse refractive telescope or a reverse afocal lens.
16. A system, comprising:
an optical modulator;
a positive optical element configured to receive coherent light and to focus the coherent light towards the optical modulator as converging light; and
a negative optical element;
the optical modulator configured to receive the converging light and to reflect the converging light towards the negative optical element as reflected light; and
the negative optical element configured to receive the reflected light from the optical modulator and to output a scan beam having a scanning field of view in accordance with the reflected light, wherein the negative optical element is configured to increase the scanning field of view.
17. The system of claim 16 , wherein the optical modulator is a digital micromirror device (DMD), an analog MEMS mirror, a phase spatial light modulator (PSLM), or a liquid crystal on silicon (LCoS) device.
18. The system of claim 16 , wherein the optical modulator is a digital micromirror device, and the system further comprising:
a processor coupled to display diffraction patterns using the digital micromirror device; wherein the diffraction patterns are corrected diffraction patterns corrected to compensate for geometric distortion in the digital micromirror device.
19. The system of claim 18 , wherein the corrected diffraction patterns are computed using a two dimensional polynomial including a correction factor.
20. The system of claim 19 , wherein computing the two dimensional polynomial includes computing:
H ( x,y )= A exp( j φ( x,y )),
where H(x, y) is the corrected diffraction pattern in two dimensions, and
jφ(x, y) is a correction factor in two dimensions for each micromirror at a position x, y.
21. A vehicle comprising:
a roof; and
a lidar system mounted on the roof, the lidar system comprising:
an illumination source configured to generate light;
an optical modulator;
a positive optical element configured to receive the light from the illumination source and to focus the light towards the optical modulator as converging light; and
a negative optical element;
the optical modulator configured to reflect the converging light to direct a scan beam towards the negative optical element; and
the negative optical element configured to receive the scan beam from the optical modulator, the negative optical element configured to output the scan beam to a scanning field of view, wherein the negative optical element is configured to increase the scanning field of view.
22. The vehicle of claim 21 , wherein the optical modulator is a digital micromirror device (DMD), an analog MEMS mirror, a phase spatial light modulator (PSLM), or a liquid crystal on silicon (LCoS) device.
23. The vehicle of claim 21 , wherein the optical modulator is a digital micromirror device, and the lidar system further comprising:
a processor coupled to display diffraction patterns using the digital micromirror device; wherein the diffraction patterns are corrected diffraction patterns corrected to compensate for geometric distortion in the digital micromirror device.
24. The vehicle of claim 23 , wherein the corrected diffraction patterns are computed using a two dimensional polynomial including a correction factor.
25. The vehicle of claim 24 , wherein computing the two dimensional polynomial includes computing:
H ( x,y )= A exp( j φ( x,y )),
where H(x, y) is the corrected diffraction pattern in two dimensions, and
jφ(x, y) is a correction factor in two dimensions for each micromirror at a position x, y.
26. The vehicle of claim 21 , wherein the positive optical element and the negative optical element together form one of a reverse refractive telescope or a reverse afocal lens.