Distance measuring apparatus

• US 8,130,368 B2
• Filed: 05/23/2008
• Issued: 03/06/2012
• Est. Priority Date: 05/25/2007
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Topcon
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: Eno, Taizo, Momiuchi, Masayuki
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): Ratcliffe, Luke
• Application Number:
  US12/126,457
• Publication Number:
  US 20090052288A1
• Time in Patent Office: 1,383 Days
• Field of Search: 356 301- 315, 356 401- 41, 356 501- 515, 356 6- 22, 356/28, 356/28.5
• US Class Current: 356/5.01
• 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 17/87 Combinations of systems using electromagnetic waves other than radio waves
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/4813 Housing arrangements
• CPC Class Codes: G01S 7/4814 of transmitters alone
• CPC Class Codes: G01S 7/4817 relating to scanning

Abstract

A distance measuring apparatus for measuring a distance to a target point in a target area comprises a laser oscillator for generating a laser beam having a first wavelength, a nonlinear crystal into which the laser beam having the first wavelength generated by the laser oscillator enters, the nonlinear crystal generating a laser beam having a second wavelength, a collimator lens at which the laser beam having the first wavelength generated by the laser oscillator and the laser beam having the second wavelength generated by the nonlinear crystal are concentrated and are transformed into parallel light flux, a laser device provided with the laser oscillator, the nonlinear crystal, and the collimator lens, an output unit for outputting the laser beam having the first wavelength and the laser beam having the second wavelength at the same time, which are emitted by the laser device, while scanning the target area, a selective reflective mirror for selectively reflecting the laser beam having the first wavelength and the laser beam having the second wavelength that are reflected at the target point in the target area, a first light receiving unit which receives the laser beam having the first wavelength selected at the selective reflective mirror and outputs a first signal, a second light receiving unit which receives the laser beam having the second wavelength selected at the selective reflective mirror and outputs a second signal, and a signal processing unit for measuring the distance to the target point in the target area by selecting one of the first signal and the second signal.

Claims

1. A distance measuring apparatus for measuring distances to a target point in a target area, comprising:

a laser oscillator for generating a laser beam having a first wavelength;

a nonlinear crystal into which the laser beam having the first wavelength generated by the laser oscillator enters, the nonlinear crystal generating a laser beam having a second wavelength;

a collimator lens at which the laser beam having the first wavelength generated by the laser oscillator and the laser beam having the second wavelength generated by the nonlinear crystal are concentrated and are transformed into parallel light flux;

an output unit for outputting the parallel light flux of the laser beam having the first wavelength and the laser beam having the second wavelength at the same time, while scanning the target area;

a dichroic mirror provided with a first reflective surface and a second reflective surface, wherein the first reflective surface selectively reflects the laser beam having the first wavelength towards a target point in a target area, and the second reflective surface selectively reflects the laser beam having the second wavelength towards the target point in the target area;

a first light receiving unit that receives the laser beam having the first wavelength that was selectively reflected by the first reflective surface and outputs a first signal;

a second light receiving unit that receives the laser beam having the second wavelength that was selectively reflected by the second reflective surface and outputs a second signal; and

a signal processing unit for measuring a distance to the target point in the target area by selecting one of the first signal and the second signal and determining the distance based on information regarding the laser beam associated with which one of the first signal and the second signal is selected by the signal processing unit.

2. The distance measuring apparatus according to claim 1, wherein the laser beam having the first wavelength is infrared light having a longer wavelength, and the laser beam having the second wavelength is a second harmonic wave of the first wavelength and is visible light having a shorter wavelength.

3. The distance measuring apparatus according to claim 1, wherein the laser oscillator comprises a laser medium, and the laser medium comprises one of a crystal and a fiber doped with one of Nd³⁺ and Er³⁺.

4. The distance measuring apparatus according to claim 1, further comprising an operating unit, wherein the laser beam having the first wavelength is used in a first measurement range and the laser beam having the second wavelength is used in a second measurement range;

and

wherein the operating unit selects one of the first measurement range and the second measurement range.

5. The distance measuring apparatus according to claim 1, further comprising an operating unit for selecting a transparency of air in the target area, and wherein the signal processing unit measures the distance to the measuring unit in the target area by selecting one of the first signal and the second signal according to the transparency of the air in the target area selected by the operating unit.

6. The distance measuring apparatus according to claim 1, further comprising an image capturing unit for capturing an image of the target area and an image processing unit for separating the image, which is captured by the image capturing unit, into an image of three colors of red, green, and blue, and wherein the signal processing unit measures the distance to the measuring unit in the target area by selecting one of the first signal and the second signal according to the color components of the image in which colors are separated by the image processing unit.

7. The distance measuring apparatus according to claim 1, wherein the signal processing unit measures the distance to the measuring unit in the target area by selecting one of the first signal and the second signal according to the intensity of light received at the first light receiving unit and the second light receiving unit.

8. The distance measuring apparatus according to claim 1, wherein the information is a speed and time of flight of the laser beam associated with which one of the first signal and the second signal is selected by the signal processing unit.