CN1142407C

CN1142407C - Method for making auxiliary measurement by using back light to irradiate line array CCD

Info

Publication number: CN1142407C
Application number: CNB021102910A
Authority: CN
Inventors: 金以丰; 陈苏民
Original assignee: Shanxi University
Current assignee: Shanxi University
Priority date: 2002-04-12
Filing date: 2002-04-12
Publication date: 2004-03-17
Anticipated expiration: 2022-04-12
Also published as: CN1380530A

Abstract

The present invention discloses an auxiliary method for measuring CCD by using back light to irradiate a linear array, which is characterized in that a uniform back light source is arranged in a CCD probe. Local or total CCD is irradiated by the light source, and signal level is moved, so the correlation signal level in an optical image of any object to be measured tends to be equal or different. The intensity of illumination of the back light source is adjusted finely, so a signal processing circuit which is composed of a comparison amplifier, a gate circuit and a trigger can be simplified. Afterwards, sampling and data processing are operated by a microprocessor, so noise can be suppressed, a system can operate more stably, and the measuring result can be adjusted finely during the measuring time.

Description

A kind of method of making auxiliary measurement by using back light to irradiate line array CCD

Technical field: the present invention relates to a kind of photoelectric measurement of physics, particularly a kind of method with making auxiliary measurement by using back light to irradiate line array CCD.

Background technology: be with a branch of directional light irradiation CCD in industrial the most frequently used measuring method at present, and place measured body in light field, measured body is between the two, can obtains unidimensional shade and corresponding echo signal on CCD, its output signal promptly is a square-wave pulse, exactly because most of CCD unit is by rayed, the noise that has suppressed CCD makes its work comparatively stable, and simple in structure, allow measured body slowly to move, make this method be applicable to most of kinetic measurement.And its shortcoming be from the source of parallel light to CCD between close together, when measurement environment is relatively poor, do not have the leeway of flexible on the structure.Another kind method is with the lens amplification or dwindles measured body, and imaging promptly gets the image that is several times as much as measured body on CCD.Signal Processing from CCD output as shown in Figure 1, makes noise filtering by wave filter, through shaping circuit signal is enlarged into square-wave signal, is added on the computer chip microprocessor through gate circuit and trigger again, carries out data acquisition and processing (DAP).The result is presented on the display among Fig. 1.Also having power unit is whole probe power supply.But under many situations, the design of shaping circuit can be met difficulty.Ccd signal instability for example, the square wave that shaping obtains is also just unstable, noise is strong excessively, amplify and the interference square wave that does not originally have, perhaps several signals of handling together are on the different level, these make all that treatment circuit is complicated and make the data instability or the mistake of computer output easily, bring puzzlement will for maintainer and user.

Summary of the invention: based on above-mentioned situation, the objective of the invention is must be weak and zone that noise is stronger obtains under the situation of echo signal from light intensity on the CCD, a kind of simplification signal processing circuit is provided, and makes CCD export stable a kind of method with making auxiliary measurement by using back light to irradiate line array CCD.

In order to achieve the above object, the present invention adopts following technical scheme.As shown in Figure 2: (1) is provided with even straight line bias light light source in the CCD probe, by this light source irradiation Local C CD, under the constant situation of original output waveform, move the level of this Local C CD signal, make that the correlation signal levels in the optical image of any concrete measured body is tending towards equal or different.(2) in the CCD probe, another homogeneous background radiant is set, shines whole CCD, obtain the fine setting of measurement result simultaneously, play the effect of calibration.Finely tune above-mentioned two kinds of bias light illumination intensity of light source, and obtain echo signal, do sampling and data processing with microprocessor again with the signal processing circuit that comparison amplifier, gate circuit and trigger constitute.(3) the I/O mouth of microprocessor is received the electric switch of above-mentioned local irradiation bias light light source, with Microprocessor Interface circuit expansion D/A converter, the bias light intensity of the whole CCD of output voltage control irradiation can be carried out programmed control with above-mentioned irradiation to CCD; Hand adjustment or program control above-mentioned two kinds of bias lights, and, do sampling and data processing with microprocessor again with the signal processing circuit acquisition echo signal that comparison amplifier, gate circuit and trigger constitute.The light source of described irradiation Local C CD is that the diaphragm by the device of the integrated circuit of adjusting irradiation brightness and straight line uniformly light-emitting and restriction field of illumination constitutes.The light source of the whole CCD of described irradiation is the bias light of the adjustable light intensity that obtains by diffusing of penetrating of diffuser or transmitted light or from fibre bundle.

The present invention's advantage and good effect compared with prior art is: be provided with the light source that can produce homogeneous background light in the magazine of original CCD probe, local or whole sections of irradiation CCD, to reach the simplification signal processing circuit, suppress the CCD noise, obtain reliable and stable echo signal and stable measuring system.Shine whole CCD, obtain the fine setting of measurement result simultaneously, play the effect of calibration.

Description of drawings: Fig. 1 is the block diagram that ccd signal is handled

Fig. 2 is a principle schematic of the present invention

Fig. 3 is the CCD waveform synoptic diagram of diffraction when calibrating

Fig. 4 is illuminated back, diffraction the 3rd a dark space waveform synoptic diagram

Fig. 5 be CCD after by full illumination waveform and be shaped as the waveform synoptic diagram of square wave

Fig. 6 is program control ccd signal and the output synoptic diagram of relatively amplifying

Fig. 7 adds local background's light and program control amplification CCD and output synoptic diagram

Embodiment: the preparation method of bias light light source of the present invention is: (1) is provided with linear pattern uniformly light-emitting led light source in the CCD probe, and is provided with diaphragm at the LED place, by this light source irradiation Local C CD.(2) in the CCD probe, another bias light light source is set, shines whole CCD.This light source can be a linear pattern uniformly light-emitting led light source; Or the bias light light source of the adjustable light intensity that obtains with diffusing of penetrating of diffuser or transmitted light or from fibre bundle.Calibrating with diffraction below is that embodiment is illustrated:

When shining a filament, beyond certain distance, place the CCD of band driving circuit, and make the central clear zone of its diffraction pattern be positioned at outside the end of CCD with beam of laser.The output signal that then available oscillograph is seen CCD as shown in Figure 3.Among the figure: 1,2,3 is respectively the 1st in the diffraction pattern, the 2nd, the 3rd dark space.Its central clear zone is outside the leftmost side of CCD.As a whole, along with away from central clear zone, just deepening thereupon of brightness; Thereby signal level raises to the upper right side.In order to record the diameter of silk, can survey the spacing between the 2nd, the 3rd dark space.But from Fig. 3, the protruding waveform of these two dark space correspondences is not but on same level.This makes troubles for the design of shaping circuit.The the 2nd, the 3rd dark space waveform all is in darker position simultaneously, and the poor stability of waveform, the square wave after the shaping are also unstable, can not do precision measurement.

By the present invention, CCD goes up the part that produces dark space 3 with the LED uniform irradiation.The waveform of the 3rd dark space correspondence is obviously descended, but keep original waveform constant, and be tending towards with high, referring to Fig. 4 with the waveform of the 2nd dark space.A suitable comparative level can be set like this, after the one-level comparison amplifier amplifies, obtain two pulses easily, just can provide the spacing of the 2nd, the 3 two dark space again through the one-level trigger; The stability of the waveform of two dark spaces also greatly improves simultaneously.

If establish above-mentioned the 2nd kind of bias light light source of a uniform irradiation whole CCD again, gained CCD waveform will be as shown in Figure 5: the waveform above among the figure is the output signal of CCD, be the stable square wave after shaping below, as can be seen from the figure: 2nd, the waveform that moves down into the 1st dark space of the waveform of the 3rd dark space correspondence is bordering on high, can obtain the square wave of three dark space correspondences with a comparison amplifier, this just brings great convenience to shaping, and their output waveform becomes very stable.With such bias light irradiation, and the signal after according to said method handling just lays the foundation for doing precision measurement.

Above-mentioned measurement also can followingly be carried out with microprocessor program control: the ccd signal of Fig. 3 is added to comparison amplifier, and comparative level hands over waveform in the P point, gets square wave as shown in Figure 6 after oppositely amplifying.Repeatedly sample and data processing by microprocessor, get its width.Next step of program connected the electric switch of the background light source of irradiation dark space 2, and the waveform of dark space 2 is descended, and draws back big gap with the waveform of dark space 3.And then once oppositely relatively amplify, get waveform as shown in Figure 7.Repeatedly sample and data processing, a width again by microprocessor again.The two subtracts each other, the spacing of the 2nd, the 3rd dark space, can be through tabling look-up or calculating the diameter of filament.

Claims

1. the method for a making auxiliary measurement by using back light to irradiate line array CCD, it is characterized in that: (1) is provided with even straight line bias light light source in the CCD probe, by this light source irradiation Local C CD section, under the constant situation of original output waveform, move the level of this Local C CD signal, make that the correlation signal levels in the optical image of any concrete measured body is tending towards equal or different; (2) in the CCD probe, another bias light light source is set, shines whole CCD; Obtain the fine setting of measurement result simultaneously, play the effect of calibration; Finely tune above-mentioned two kinds of bias light illumination intensity of light source, and obtain echo signal, do sampling and data processing with microprocessor again with the signal processing circuit that comparison amplifier, gate circuit and trigger constitute; (3) the I/O mouth of microprocessor is received the electric switch of above-mentioned local irradiation bias light light source; With Microprocessor Interface circuit expansion D/A converter, the bias light intensity of the whole CCD of output voltage control irradiation can be carried out programmed control with above-mentioned irradiation to CCD; Hand adjustment or program control above-mentioned two kinds of bias lights, and, do sampling and data processing with microprocessor again with the signal processing circuit acquisition echo signal that comparison amplifier, gate circuit and trigger constitute.

2. the method for a kind of making auxiliary measurement by using back light to irradiate line array CCD according to claim 1, the light source that it is characterized in that described irradiation Local C CD are that the diaphragm by the device of the integrated circuit of adjusting irradiation brightness and straight line uniformly light-emitting and restriction field of illumination constitutes.

3. the method for a kind of making auxiliary measurement by using back light to irradiate line array CCD according to claim 1, the light source that it is characterized in that the whole CCD of described irradiation are the bias lights of the adjustable intensity that obtains by diffusing of penetrating of diffuser or transmitted light or from fibre bundle.