Scanner for airborne laser system

• US 6,723,975 B2
• Filed: 02/05/2002
• Issued: 04/20/2004
• Est. Priority Date: 02/07/2001
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Saccomanno, Robert J.
• Primary Examiner(s): Smith, Zandra V.
• Application Number:
  US10/068,740
• Publication Number:
  US 20020149761A1
• Time in Patent Office: 805 Days
• Field of Search: 356/337-343, 356/446, 359/212-215, 250/201.1, 250/203--20, 250/203.6
• US Class Current: 250/203.6
• CPC Class Codes: G01C 5/005 altimeters for aircraft G01C5/02, G01C5/06 take precedence
• CPC Class Codes: G01P 13/025 indicating air data, i.e. flight variables of an aircraft, e.g. angle of attack, side slip, shear, yaw
• CPC Class Codes: G01P 5/20 using particles entrained by a fluid stream G01P5/22 takes precedence
• CPC Class Codes: G01P 5/26 by measuring the direct influence of the streaming fluid on the properties of a detecting optical wave
• CPC Class Codes: G01S 17/933 of aircraft or spacecraft
• CPC Class Codes: G01S 7/4811 common to transmitter and receiver
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

A multi-axis laser scanner and receiver capable of providing laser scanning in multiple fields of view using a microscanner and a fold mirror with a patterned aperture. The fold mirror has a transmissive central region and a periphery that is reflective. Such scanners can be employed in a helicopter to scan in the forward field of view for obstacle detection, and in an upward field of view for air data measurements. Additional fields of view can be added, for example, to provide downward scans to detect height above terrain and ground speed.

Claims

1. An apparatus for directing laser energy to a plurality of targets in multiple fields of view, and receiving the scattered returns therefrom, comprising:

a plurality of condensing optical elements for collecting said scattered returns;

a plurality of windows for allowing said laser energy to pass therethrough;

an optical enclosure being formed from a combination of said condensing optical elements and said windows;

a multiple-axis scanning mirror positioned to receive a laser beam, said multiple-axis scanning mirror directing said laser beam into one or more predetermined scan patterns; and

a fold mirror with patterned aperture positioned to intercept the laser scan pattern, from said scanning mirror, said fold mirror directing a first portion of said laser scan pattern along a first field of view and a second portion of said laser scan pattern along a second field of view.

2. The apparatus in accordance with claim 1 wherein said multiple-axis scanning mirror is located within said optical enclosure and receives said laser beam through an aperture in said optical enclosure.

3. The apparatus in accordance with claim 1 wherein said fold mirror further comprises:

a transmissive central region passing said first portion of said laser scan pattern therethrough; and

a periphery deflecting said second portion of said laser scan pattern in a direction along said second field of view.

4. The apparatus in accordance with claim 1 further comprising a plurality of detectors, each detector converting said scattered returns collected from a respective condensing optical element into electrical signals.

5. The apparatus of claim 1 wherein said condensing optical element is selected from the group consisting of imaging optical elements, non-imaging optical elements, reflective optical elements, refractive optical elements, diffractive optical elements, and holographic optical elements.

6. The apparatus of claim 1 wherein said periphery includes a light directing element selected from the group consisting of reflective elements, refractive elements, diffractive elements, and holographic elements.

7. The apparatus of claim 3 wherein said transmissive central region is selected from the group consisting of a physical hole, a holographic element, a partially-transparent refractive element, and a substantially-transparent refractive element.

8. The apparatus of claim 1 wherein said fold mirror is tilted at a predetermined angle with respect to the laser energy from said scanning mirror.

9. The apparatus of claim 8 wherein said fold mirror with patterned aperture comprises a plurality of holographic optical elements.

10. The apparatus of claim 8 wherein said fold mirror with patterned aperture comprises one or more electrically switchable holographic optical elements.

11. A laser scanner for directing laser energy to a plurality of targets in multiple fields of view, and receiving the scattered returns therefrom, comprising:

a plurality of condensing optical elements for collecting said scattered returns,

a plurality of windows for allowing said laser energy to pass therethrough;

an optical enclosure being formed from a combination of said condensing optical elements and said windows;

a multiple-axis scanning mirror located external to said optical enclosure and positioned to receive a laser beam, said multiple-axis scanning mirror directing said laser beam through an aperture into said optical enclosure and forming a laser scan pattern therefrom;

a fold mirror with patterned aperture located within said optical enclosure and positioned to intercept the laser scan pattern, said fold mirror comprising,

a transmissive central region passing a first portion of said laser scan pattern therethrough in a direction substantially along a first field of view, and

a periphery deflecting a second portion of said laser scan pattern in a direction along a second field of view; and

a plurality of detectors, each detector located proximal to said optical enclosure to convert said scattered returns collected from a respective condensing optical element into electrical signals.

12. The laser scanner of claim 11 further comprising beam expansion optics.