Rangefinder with a laser-like light source

• US 10,175,343 B2
• Filed: 12/03/2015
• Issued: 01/08/2019
• Est. Priority Date: 12/04/2014
• Status: Active Grant

• Current Assignee: Hexagon Technology Center GmbH (Hexagon AB)
• Original Assignee: Hexagon Technology Center GmbH (Hexagon AB)
• Inventors: Stutz, Reto, Hinderling, Jurg
• Primary Examiner(s): Bolda, Eric L
• Application Number:
  US14/958,777
• Publication Number:
  US 20160161598A1
• Time in Patent Office: 1,132 Days
• CPC Class Codes: G01S 17/10 using transmission of interrupted, pulse-modulated waves determination of distance by phase measurements G01S17/32
• CPC Class Codes: G01S 17/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S17/46
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/4818 using optical fibres
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: H01S 3/06754 Fibre amplifiers H01S3/06708 takes precedence
• CPC Class Codes: H01S 5/3031 Si

Abstract

Some embodiments of the invention may relate to a rangefinder, in particular for a laser scanner, laser tracker, profiler, theodolite, or a total station. In a special embodiment of the invention, the light source of the rangefinder—provided for the emission of pulsed light signals—is configured here as an optical fiber amplifier (e.g. an EDFA, i.e. erbium-doped fiber amplifier) which is optically pumped by a superluminescent diode (SLD) operated in a pulsed manner.

Claims

1. An electro-optical rangefinder comprising:

light emission means for emitting at least one light signal, in particular for emitting a pulsed light signal, the light emission means comprising;

a spectrally broadband light source as primary light source, and

an optical amplifier disposed downstream of the primary light source, in particular wherein an actively pumped medium of the optical amplifier serves as a light amplifier without a resonator, in particular wherein the optical amplifier is provided and embodied precisely to be operated with a modulation sequence with a short and/or long duty cycle;

a receiver for detecting the light signal scattered back from a target object; and

a control and evaluation component for determining a distance to the target object, in particular wherein the determination is based upon the pulse time-of-flight measurement method.

2. The rangefinder according to claim 1, wherein the rangefinder comprises at least one of a laser scanner, laser tracker, profiler, theodolite, and a total station.

3. The rangefinder according to claim 1, wherein:

the primary light source is operable in a single pulse mode.

4. The rangefinder according to claim 1, wherein:

the primary light source is operated in a burst mode.

5. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a superluminescent diode (SLD).

6. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a superluminescent diode (SLD) with a spectral emission width between 7 nm and 50 nm.

7. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a combination of a plurality of superluminescent diodes (SLDs).

8. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a high radiance LED.

9. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a semiconductor laser diode which emits a plurality of modes and polychromatic light with a plurality of spectral lines.

10. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a broad stripe laser diode or VCSEL (vertical cavity surface emitting laser) laser diode which emits spatially multimode and polychromatic light, in particular with a spatial emission width of between 10 μ

m and 300 μ

m.

11. The rangefinder according to claim 1, wherein:

the primary light source is embodied as a superluminescent diode (SLD) and is directly modulable by sub-nanosecond pulses.

12. The rangefinder according to claim 1, wherein:

the optical amplifier disposed downstream of the primary light source is embodied as a fiber amplifier, in particular as a glass fiber amplifier, doped with a rare earth metal such as Y, Yb, Pr, Ho, Tm, Er, or any combinations thereof.

13. The rangefinder according to claim 12, wherein:

the fiber amplifier has a fiber core diameter that is greater than the diffraction limit.

14. The rangefinder according to claim 12, wherein:

the fiber amplifier has a fiber core diameter that is greater than the diffraction limit comprising a so-called “

large core”

fiber.

15. The rangefinder according to claim 1, wherein:

the optical amplifier disposed downstream of the primary light source is embodied as a Raman amplifier.

16. The rangefinder according to claim 1, wherein:

the optical amplifier disposed downstream of the primary light source is embodied as an SiO2 fiber amplifier.

17. The rangefinder according to claim 1, wherein:

the optical amplifier disposed downstream of the primary light source is embodied as a semiconductor amplifier.

18. The rangefinder according to claim 1, wherein:

the optical amplifier disposed downstream of the primary light source is embodied as a semiconductor amplifier based on a material such as SOA.

19. The rangefinder according to claim 1, wherein:

the area of the reception aperture (RXA) of the receiver is at least 50 times larger than the cross-sectional area of the transmission beam.

20. The rangefinder according to claim 1, wherein:

the area of the reception aperture (RXA) of the receiver is at least 50 times greater than the cross-sectional area of the transmission beam incident on the target object.

21. The rangefinder according to claim 1, wherein:

the receiver is equipped with a reception diode comprising a plurality of segments.

22. The rangefinder according to claim 1, wherein:

the receiver comprises a reception diode having a multi-segment PIN diode or APD.

23. The rangefinder according to claim 1, wherein:

the receiver compromises an autofocus.