Light-wave rangefinder using a pulse method

• US 6,665,055 B2
• Filed: 12/16/2002
• Issued: 12/16/2003
• Est. Priority Date: 12/18/2001
• Status: Active Grant

• Current Assignee: Topcon KK
• Original Assignee: Kabushiki Kaisha Topcon
• Inventors: Ohishi, Masahiro, Tokuda, Yoshikatsu
• Primary Examiner(s): Buczinski, Stephen C.
• Application Number:
  US10/320,234
• Publication Number:
  US 20030142287A1
• Time in Patent Office: 365 Days
• Field of Search: 356/5-1-, 342/134, 342/135, 342/203, 342/202, 342/204
• US Class Current: 356/5.01
• CPC Class Codes: G01C 3/08 Use of electric radiation detectors
• CPC Class Codes: G01S 17/14 wherein a voltage or current pulse is initiated and terminated in accordance with the pulse transmission and echo reception respectively, e.g. using counters
• CPC Class Codes: G01S 7/487 Extracting wanted echo signals , e.g. pulse detection
• CPC Class Codes: G01S 7/4873 by deriving and controlling a threshold value
• CPC Class Codes: G01S 7/497 Means for monitoring or calibrating

Abstract

The present invention relates to a light-wave rangefinder using a pulse method, which can reduce a measurement error, in which a tuned amplifier converts an electric signal of a light receiving unit into a damped oscillation waveform and thereby an arithmetic processing means can calculate a distance from a measuring position to a reflecting object on the basis of the damped oscillation waveform of the tuned amplifier. An optical noise sampling unit samples an optical noise produced in the rangefinder; an optical-noise storage unit stores sampling data of the optical-noise sampling unit; an arithmetic processing means reduces a measurement error caused by an optical noise on the basis of the sampling data of the optical-noise storage unit; and thereby a distance, a measurement error of which is reduced, can be calculated.

Claims

1. A light-wave rangefinder using a pulse method, comprising:

a light-emitting unit for emitting pulsed measuring luminous flux toward a target to be measured;

a light receiving unit for receiving the luminous flux reflected by the target to be measured, and converting the luminous flux into an electric signal;

a tuned amplifier for converting the electric signal of the light receiving unit into a damped oscillation waveform;

an arithmetic processing means for calculating a distance from a measuring position to a reflecting object on the basis of the damped oscillation waveform of the tuned amplifier;

an optical-noise sampling unit for sampling an optical noise produced in the light-wave rangefinder; and

an optical-noise storage unit for storing sampling data of the optical-noise sampling unit;

wherein said arithmetic processing means reduces a measurement error caused by the optical noise on the basis of the sampling data of the optical-noise storage unit, and thereby calculates a distance, a measurement error of which is reduced.

2. A light-wave rangefinder using a pulse method according to claim 1, wherein said arithmetic processing means comprises:

a sampling unit for sampling a damped oscillation waveform of the tuned amplifier at given sampling intervals;

a storage unit for storing sampling data of the sampling unit; and

a distance calculating unit for calculating a distance from a measuring position to a reflecting object on the basis of the sampling data of the storage unit,

said sampling unit and said storage unit being also used as the optical-noise sampling unit and the optical-noise storage unit, respectively.