Light receiving circuit of laser range finder

Details Light receiving circuit of laser range finder Light receiving circuit of laser range finder

2001-02-12

2003-01-28

Tarcza, Thomas H. (Department: 3662)

Optics: measuring and testing

Range or remote distance finding

With photodetection

Reexamination Certificate

active

06512574

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to a device of distance measurement based on laser, and more particularly to a light receiving circuit of the laser range finder.
BACKGROUND OF THE INVENTION
Laser range finder is one of the important devices for measuring the distance. Traditionally, a laser range finder employs a pulse type of the laser transmitter to transmit short laser pulse of about 20 ns onto a target. The reflected laser signal from the target is received by employing a low noise, high sensitivity laser receiver to evaluate the distance by the following formula:
T
d
=2
L/C,
  (1)
Where L is the distance, C is the speed of light, and T
d
is time delay between the firing laser pulse and received laser pulse. A precise distance can be obtained by measuring T
d
according to the formula (1). In order to precisely measure the time delay T
d
, it needs to increase the transmitted laser power as much as possible or to remove the noise induced by the sunlight in the optical receiver. U.S. Pat. No. 3,644,740 discloses that the signal-to-noise ratio of the receive circuit is improved by controlling the circuit bias on the receiver circuit to get a fixed false alarm. With reference to U.S Pat. No. 4,569,599, a timing control technique is disclosed to detect the distance signal. U.S. Pat. No. 4,770,526 further discloses a technique of amplifying time delay signal to increase the resolution of distance detection. A technique of digital ranging is also disclosed in U.S. Pat. No. 3,959,641 to reduce the threshold value of the optical receiver so as to increase the measured distance.
U.S. Pat. No. 5,612,779 uses an automatic noise threshold determining circuit to get a maximum sensitivity of the laser receiver. A fast charge and slow discharge circuit is also adopted to improve the distance resolution.
In this invention, we will propose a light receiving receiver with a bias stabilized main amplifier followed by a one-shot circuit to get a digital output signal with fixed pulse width. This light receiver circuit can provide a function of maximum sensitivity for the laser receiving circuit, therefore the ranging distance of the laser range finder can also be improved effectively.
SUMMARY OF THE INVENTION
The primary objective of the present invention is to provide a laser range finder with light receiving circuit capable of enhancing the sensitivity of the receiving laser signal.
The light-receiving circuit of the laser range finder of the present invention comprises a photosensitive element, a conversion amplifier, a main amplifier, and a one-shot circuit. The photosensitive element converts a received light signal into a current signal, which is then converted into a voltage signal by the conversion amplifier. A main amplifier to get amplification with very high gain then amplifies the output voltage signal of conversion amplifier. The one-shot circuit into a digital signal with fixed pulse width then shapes the output voltage of the main amplifier. This digital signal is then adopted for using in the range-finding process of the laser range finder.


REFERENCES:
patent: 3644740 (1972-02-01), Dobratz et al.
patent: 3959641 (1976-05-01), Miller, Jr. et al.
patent: 4569599 (1986-02-01), Bölkow et al.
patent: 4678323 (1987-07-01), Sato et al.
patent: 4681432 (1987-07-01), Kawabata et al.
patent: 4770526 (1988-09-01), Manhart et al.
patent: 5357331 (1994-10-01), Flockencier
patent: 5396510 (1995-03-01), Wilson
patent: 5612779 (1997-03-01), Dunne
patent: 5767953 (1998-06-01), McEwan
patent: 6103546 (2000-08-01), Lee
patent: 6115114 (2000-09-01), Berg et al.
patent: 6259321 (2001-07-01), Song et al.
patent: 6310682 (2001-10-01), Gavish et al.

Affiliated with

Also associated with

Rating

Light receiving circuit of laser range finder does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Light receiving circuit of laser range finder, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Light receiving circuit of laser range finder will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3016974