US 6,388,754 B1Granted

Shape measuring system and method

AssigneeFuji Xerox Co., Ltd.

InventorsOsamu Nishikawa, Yoshinori Yamaguchi, Kiwame Tokai

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Abstract

A shape measuring system reduced in size and cost and high in the light utilization efficiency, as well as a shape measuring method, are disclosed which can measure the distance up to an object accurately without being influenced by external conditions such as a change in reflectance of the surface of the object. A semiconductor laser emits an intensity-modulated illumination light. A plane sensor detects a combined light of both a reflected light from an object and a reference light and outputs a composite light detection signal. The semiconductor laser also emits an illumination light which is a stationary light not intensity-modulated. At this time, a shutter is closed. The plane sensor detects the reflected light from the object and outputs a detection signal thereof. For the composite light detection signal a distance calculator makes correction for eliminating the influence of reflectance of the object on the basis of a detection signal of a reflected stationary light and thereafter calculates the distance up to the object on the basis of the composite light detection signal after the correction.

Claims19

Dependent claims

A shape measuring system wherein a light having been intensity-modulated at a predetermined frequency is emitted toward an object and the distance up to said object is determined on the basis of a phase difference between reflected light from said object and said emitted light, said shape measuring system comprising:

a light emitting unit that emits said light having been intensity-modulated at said predetermined frequency and emits a stationary light not intensity-modulated toward said object;
a reflecting member that reflects in a predetermined direction a part of said light emitted from said light emitting unit and a part of said stationary light;
a detecting unit that receives said light reflected from said object and also receives said light reflected by said reflecting member and outputs a composite detection signal produced by combining both said received lights and with said phase difference reflected therein, said detecting unit further receiving the stationary light reflected by said object by said stationary light and outputting a reflected stationary light detection signal, said detecting unit further receiving the stationary light from said reflecting member and outputting a stationary light detection signal;
and
a calculating unit that, in accordance with said composite detection signal, said reflected stationary light detection signal and said stationary light detection signal, corrects for a change in reflectance of said object, and calculates said distance.

2 more elements

A shape measuring method wherein light having been intensity-modulated at a predetermined frequency is emitted toward an object and the distance up to said object is determined on the basis of a phase difference between reflected light from said object and said emitted light, said shape measuring method comprising:

a first step of emitting said light intensity-modulated at said predetermined frequency toward said object, detecting said reflected light and said emitted light, combining both said lights into a composite detection signal with said phase difference reflected therein, emitting a stationary light not intensity-modulated toward said object, detecting the stationary light reflected from the object, converting the reflected stationary light thus detected into a reflected stationary light detection signal, and detecting said stationary light and converting it into a stationary light detection signal;
and
a second step of correcting a change in reflectance of said object and calculating said distance, in accordance with said composite detection signal, said reflected stationary light detection signal and said stationary light detection signal.

Dependencies are inferred from the claim text.