Low cost laser range finder system architecture

• US 5,638,163 A
• Filed: 06/07/1995
• Issued: 06/10/1997
• Est. Priority Date: 06/07/1995
• Status: Expired due to Term

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Hughes Electronics Corporation (AT&T, Inc.)
• Inventors: Nourrcier, Charles E. Jr.
• Primary Examiner(s): Hellner, Mark
• Application Number:
  US08/476,922
• Time in Patent Office: 734 Days
• Field of Search: 356/5.01, 356/5.05, 356/6
• US Class Current: 356/5.01
• CPC Class Codes: G01S 17/18 wherein range gates are used
• CPC Class Codes: G01S 17/89 for mapping or imaging
• CPC Class Codes: G01S 7/484 Transmitters
• CPC Class Codes: G01S 7/486 Receivers
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating
• CPC Class Codes: G01S 7/51 Display arrangements

Abstract

A laser range finder including a receiver for detecting a return pulse and providing an output signal indicative thereof, a single integrated circuit digital range counter chip connected to receive the output signal from the receiver, a power supply unit for powering the receiver and range counter chip, and a single-chip microcontroller for selectively sequencing application of power to the receiver and to the range counter chip, for controlling laser firing, and for automatically recalibrating the receiver.

Claims

1. A laser range finder apparatus comprising:

receiver means including a detector and means for providing a plurality of output signals indicative of the state of said receiver means, said receiver means being responsive to at least one calibration signal to adjust the performance thereof; and

means for generating a laser pulse, for receiving a return pulse and supplying at least a portion of the return pulse to said detector;

power supply means for selectively supplying power to said means for generating said laser pulse, to said receiver means, and to said detector in response to a plurality of power control signals; and

programmed controller means responsive to said output signals for calibrating said receiver means by supplying said at least one calibration signal to said receiver means and for selectively supplying said power control signals to said power supply means.

2. The laser range finder apparatus of claim 1 further including digital circuit means including digital range counter means for generating a count representative of the time interval between firing of said laser pulse and detection of a return pulse by said receiver means, said controller means further controlling said power supply means to selectively supply power to said digital range counter means.

3. The laser apparatus of claim 2 wherein said digital circuit means further includes IFF counter means for generating a count indicative of the interval between a laser fire command and the actual firing of the laser and supplying said count to said controller means.

4. The laser apparatus of claim 2 wherein said digital circuit means further includes programmable range gate means for selecting an interval of time during which said range counter means is enabled to count.

5. The laser apparatus of claim 2 wherein said digital circuit means further includes delay line differentiator means for triggering operation of said range counter means.

6. The laser apparatus of claim 3 wherein said digital circuit means further includes programmable range gate means for selecting an interval of time during which said range counter means is enabled to count.

7. The laser apparatus of claim 6 wherein said digital circuit means further includes delay line differentiator means for triggering operation of said range counter means.

8. The laser range finder apparatus of claim 7 further including display means for displaying parameters related to operation of said laser range finder, said controller means further being operable to control the display provided by said display means.

9. The laser range finder apparatus of claim 1 wherein said controller means is field reprogrammable to vary selected parameters.

10. The laser range finder apparatus of claim 5 wherein said controller means include storage means for storing a plurality of said parameters, said storage means being partitioned into a table means for storing said parameters and a code storage means for storing executable program code.

11. The laser range finder apparatus of claim 1 wherein said output signals include a voltage offset signal and a voltage indicative of detector temperature and wherein said at least one calibration signal includes a calibration voltage.

12. The laser range finder apparatus of claim 11 wherein said receiver means is further responsive to calibration signals comprising up and down current control signals.

13. In a laser range finder apparatus comprising means for generating and outputting a laser pulse, a receiver means for receiving and detecting an optical return pulse and providing a signal indicative of the detection of a said return pulse, a range counter means for counting the interval between an output laser pulse and a return pulse, and power supply means for powering said generating means, receiver means, and range counter means, the improvement comprising:

means for sequencing the application of power to said receiver means and range counter means and for recalibrating said receiver means during a plurality of selected time intervals.

14. The laser range finder apparatus of claim 13 wherein said receiver means includes an optical detector requiring a bias voltage and wherein said recalibrating includes adjustment of said bias voltage.

15. The laser range finder apparatus of claim 13 wherein said recalibrating includes false alarm rate adjustment.

16. The laser range finder apparatus of claim 14 wherein said bias voltage adjustment is performed after detection of a selected change in temperature of said detector by said means for sequencing and recalibrating.

17. The laser range finder apparatus of claim 13 wherein said means for sequencing and recalibrating includes a programmed controller means.

18. A method of controlling laser range finder apparatus including a receiver comprising the steps of:

monitoring the state of said receiver under control of a stored program;

periodically recalibrating said receiver under control of said stored program; and

sequencing the application of power to said receiver and range counter under control of said stored program.

19. The method of claim 18 wherein said receiver includes an optical detector requiring a bias voltage and wherein said step of recalibrating includes the steps of:

setting said bias voltage at a selected level to cause an initially high false alarm rate; and

incrementally decreasing said bias voltage while monitoring said false alarm rate until a desired false alarm rate is achieved.

20. The method of claim 18 wherein said receiver includes an optical detector and wherein said step of recalibrating includes the steps of:

adjusting a calibration signal level with no light on the optical detector until an offset voltage level is equal to zero;

monitoring a false alarm rate; and

adjusting said calibration signal level until a selected false alarm rate is achieved.

21. The method of claim 20 wherein said step receiver includes a detector and said step of recalibrating includes the steps of:

monitoring the detector temperature; and

recalibrating said receiver in response to detection of a variation of said temperature from a reference temperature by a selected amount.

22. A laser range finder apparatus comprising:

receiver means for detecting a return pulse and providing an output signal indicative thereof;

a single integrated circuit chip connected to receive said signal from said receiver means and having a digital range counter and digital return storage circuitry fabricated therein;

a power supply means for powering said receiver means and integrated circuit chip; and

a single-chip programmed processor means for sequencing power to said receiver means and integrated circuit chip, for controlling laser firing, and for recalibrating said receiver means.

23. The laser range finder apparatus of claim 22 further including display means for displaying parameters related to operation of said laser range finder apparatus.