Ladar transmitter with ellipsoidal reimager

Patent metadata

Field	Value
Publication number	US-12078798-B2
Application number	US-202318233033-A
Country	US
Kind code	B2
Filing date	Aug 11, 2023
Priority date	Feb 18, 2016
Publication date	Sep 3, 2024
Grant date	Sep 3, 2024

Abstract

Disclosed herein is a compact beam scanner assembly that includes an ellipsoidal reimaging mirror.

First claim

What is claimed is:

1. A ladar scanning system comprising:
a light source; and
an elliptical conjugate reflector (ECR) assembly that scans light from the light source into a scan area; and
wherein the ECR assembly comprises a first scan mirror, a second scan mirror, and an ellipsoidal mirror;
wherein the first scan mirror is rotatable about a first rotation axis;
wherein the second scan mirror is rotatable about a second rotation axis;
wherein the ellipsoidal mirror reimages light from the first scan mirror onto the second scan mirror;
wherein the ellipsoidal mirror has a reflective face that is shaped as a section of a hollow ellipsoid, wherein the hollow ellipsoid is rotationally symmetric about a symmetry axis, wherein the hollow ellipsoid defines an ellipse that lies in a plane that includes the symmetry axis, and wherein the ellipse exhibits a first focus and a second focus that lie on the symmetry axis;
wherein the light source is positioned to emit light onto the first focus, wherein the first rotation axis passes through the first focus, and wherein the second rotation axis passes through the second focus;
wherein the first scan mirror is positioned to receive and reflect the emitted light from the light source to scan light toward the reflective face of the ellipsoidal mirror as the first scan mirror rotates about the first rotation axis;
wherein the reflective face of the ellipsoidal mirror is positioned as an offset ellipsoidal reimager over the second scan mirror so that the reflective face of the ellipsoidal mirror receives and reflects the scanned light from the first scan mirror toward the second focus;
wherein the second scan mirror is positioned to receive and reflect the scanned light from the reflective face of the ellipsoidal mirror as the second scan mirror rotates about the second rotation axis; and
wherein the first and second rotation axes are arranged to produce scanning by the ECR assembly of the emitted light from the light source through different azimuths and elevations in the scan area in response to rotations of the first and second scan mirrors about the first and second rotation axes respectively.

2. The system of claim 1 wherein the first scan mirror is centered on the first focus, and wherein the second scan mirror is centered on the second focus.

3. The system of claim 1 wherein the reflective face of the ellipsoidal mirror is centered around a point on the hollow ellipsoidal that intersects with a line passing through the second focus that is perpendicular to the symmetry axis.

4. The system of claim 1 wherein the scanned light from the first scan mirror exhibits a first ray fan that is incident on the reflective face of the ellipsoidal mirror, wherein the ellipsoidal mirror produces a second ray fan in response the first ray fan, wherein the second ray fan is incident on the second scan mirror;
wherein the first ray fan is defined by rays of light that are coplanar with each other; and
wherein the second ray fan is defined by rays of light that are coplanar with each other.

5. The system of claim 4 wherein the ECR assembly scans through azimuths and elevations within the scan area according to a substantially rectilinear scan pattern.

6. The system of claim 1 wherein the ECR assembly scans through azimuths and elevations within the scan area according to a substantially rectilinear scan pattern.

7. The system of claim 1 wherein the first and second rotation axes are perpendicular to each other.

8. The system of claim 1 wherein the first rotation axis lies in the plane in which the ellipse lies, and wherein the second rotation axis is normal to the plane in which the ellipse lies.

9. The system of claim 1 wherein the ellipse has a major axis and a minor axis, and wherein the symmetry axis is the major axis of the ellipse.

10. The system of claim 1 wherein one of the first and second scan mirrors scans at a resonant frequency, and wherein the other of the first and second scan mirrors is step-scanned.

11. The system of claim 1 further comprising:
a processor configured to define a shot list for the system based on an intelligent selection of a subset of range points in the scan area for targeting with ladar pulse shots from the light source, wherein the ladar pulse shots are targeted toward the range points via reflections from the first scan mirror to the ellipsoidal mirror and from the ellipsoidal mirror to the second scan mirror as the first and second scan mirrors rotate about the first and second rotation axes respectively.

12. The system of claim 1 wherein the first scan mirror has a reflective face that exhibits an offset tilt angle α relative to the symmetry axis in the plane in which the ellipse lies, wherein the first rotation axis is also tilted at the offset tilt angle α relative to the symmetry axis in the plane in which the ellipse lies.

13. The system of claim 1 wherein an offset angle is imposed on the second scan mirror to facilitate exit of the scanned light from the ECR assembly.

14. The system of claim 1 further comprising:
a lens that is positioned optically between the light source and the first scan mirror, wherein the lens focuses the light from the light source onto the first scan mirror.

15. The system of claim 1 further comprising:
a ladar receiver that (1) receives a reflection of the scanned light from an object in the scan area and (2) processes the received reflection to determine a range to the object, and wherein the ECR assembly is offset from the ladar receiver so that an optical path of scanned light from the ECR assembly to the object and an optical path of the reflection from the object to the ladar receiver are different optical paths.

16. The system of claim 1 wherein the first scan mirror and the second scan mirror comprise MEMS mirrors.

17. The system of claim 1 wherein the first and second scan mirrors are positioned in a side-by-side arrangement.

18. The system of claim 1 further comprising:
an optical field splitter/inverter positioned optically downstream from the first and second scan mirrors to split and invert the scan area.

19. A ladar scanning system comprising:
a light source; and
an elliptical conjugate reflector (ECR) assembly that scans light from the light source into a scan area; and
wherein the ECR assembly comprises a first scan mirror, a second scan mirror, and an ellipsoidal mirror;
wherein the first scan mirror is rotatable about a first rotation axis;
wherein the second scan mirror is rotatable about a second rotation axis;
wherein the ellipsoidal mirror reimages light from the first scan mirror onto the second scan mirror;
wherein the ellipsoidal mirror has a reflective face that is shaped as a section of a hollow ellipsoid, wherein the hollow ellipsoid is rotationally symmetric about a symmetry axis, wherein the hollow ellipsoid defines an ellipse that lies in a plane that includes the symmetry axis, and wherein the ellipse exhibits a first focus and a second focus that lie on the symmetry axis;
wherein the light source is positioned to emit light onto the first focus, wherein the first rotation axis passes through the first focus, and wherein the second rotation axis passes through the second focus;
wherein the first scan mirror is positioned to receive and reflect the emitted light from the light source to scan light toward the reflective face of the ellipsoidal mirror as the first scan mirror rotates about the first rotation axis;
wherein the reflective face of the ellipsoidal mirror is

Assignees

• Aeye Inc

Inventors

• Dussan Luis Carlos
• Demmer David R
• Stockton John
• Steinhardt Allan
• Cook David

Classifications

• G02B27/141

  using dichroic mirrors · CPC title

• G02B27/14

  operating by reflection only · CPC title

• G01S7/497

  Means for monitoring or calibrating · CPC title

• G01S17/42

  Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) · CPC title

• G02B27/126

  The splitting element being a prism or prismatic array, including systems based on total internal reflection · CPC title