Laser operation for survey instruments

• US 20080084902A1
• Filed: 11/28/2007
• Published: 04/10/2008
• Est. Priority Date: 03/16/2004
• Status: Active Grant

• Current Assignee: Leica Geosystems AG (Hexagon AB)
• Original Assignee: Leica Geosystems AG (Hexagon AB)
• Inventors: Walsh, Gregory, Storz, Ralph
• Granted Patent: US 7,697,581 B2
• Time in Patent Office: Days
• US Class Current: 372/33
• CPC Class Codes: G01C 15/002 Active optical surveying means optical plumbing G01C15/105
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

The performance of a laser scanner is optimized in the field by automatically determining appropriate laser parameters for the scan location. A laser control system uses information such as the environmental temperature to select an appropriate range of start points for various laser parameters, such as pump temperature and laser currents. Test pulses over that range can be used to determine optimal operating parameters.

Claims

1. A method of automatically selecting operating parameters for a surveying instrument, comprising the steps of:

measuring a current environmental value for at least one environmental parameter outside the surveying instrument;

selecting a range of test values for at least one operating parameter using the current environmental value;

firing series of test pulses using test values selected from the range of test values;

measuring an average delay for each series of test pulses; and

using the average delay to select optimal test values and setting those optimal test values as the operating parameters for the surveying instrument.

2. A method according to claim 1, wherein:

the at least one environmental parameter is selected from the group consisting of temperature, pressure, and light level.

3. A method according to claim 1, wherein:

the first and second operating parameters include at least one parameter selected from the group consisting of idle current, pulse current, power, timing delay, pulse timing, pump temperature, laser temperature, pulse intensity, output wavelength, output power, and pulse stability.

4. A method according to claim 1, wherein:

selecting a range of test values includes selecting test values over a search space for the laser scanner.

5. A method of automatically selecting operating parameters for a surveying instrument, comprising the steps of:

positioning the surveying instrument near an object to be scanned;

firing at least one test pulse in order to determine a current operating value for at least one first operating parameter of the laser scanner;

measuring a current environmental value for at least one environmental parameter; and

using the current operating value and the current environmental value to automatically determine an optimal value for at least one second operating parameter.

6. A method according to claim 5, wherein:

using the current operating value and the current environmental value to automatically determine an optimal value includes using at least one search algorithm.

7. A system for automatically selecting operating parameters for a laser scanner, comprising:

an optical transceiver including a laser for emitting a scan pulse and a detector for receiving a reflected portion of the scan pulse;

a laser temperature detection device positioned relative to the laser to determine a current operating temperature of the laser;

a laser temperature regulation device positioned relative to the laser to adjust the current operating temperature of the laser;

an external temperature sensor operable to determine an environmental temperature about the laser scanner; and

a laser control device in communication with the optical transceiver, laser temperature regulation device, laser temperature detection device, and external temperature sensor, the laser control device operable to use the environmental temperature and operating temperature to automatically select an optimal operating temperature for the laser.

8. A system according to claim 7, wherein:

the laser temperature regulation device is a thermoelectric cooler.

9. A system according to claim 7, wherein:

the laser temperature detection device is a thermistor.

10. A system according to claim 7, wherein:

the laser includes a diode pump laser, whereby the laser temperature regulation device regulates the temperature of the diode pump laser and the laser temperature detection device measures the current operating temperature of the diode pump laser.

11. A system according to claim 7, wherein:

the laser control device is further operable to use only the environmental temperature to automatically select an optimal operating temperature for the laser.

12. A system for automatically selecting operating parameters for a laser scanner, comprising:

an optical transceiver including a laser for emitting a scan pulse and a detector for receiving a reflected portion of the scan pulse;

a laser parameter measurement device operable to determine a current operating value for at least one first laser operating parameter;

an environmental parameter measurement device operable to determine an environmental value for at least one environmental parameter; and

a laser control device in communication with the optical transceiver, laser parameter measurement device, and environmental parameter measurement device, the laser control device operable to use the environmental value and current operating value to automatically select an optimal value for at least one second operating parameter.

13. A system according to claim 12, wherein:

the at least one second operating parameter includes at least one of the at least one first operating parameters.