CN108507493A - A kind of test system of comprehensive more sensing three-dimensional optical gauge heads - Google Patents

Abstract

The invention discloses a test system for an all-round multi-sensing three-dimensional optical measuring head, which comprises a microscopic objective lens, an LED lighting source, an industrial CCD camera, an infrared beam splitter, a barrel lens, more than one collimating mirror, and a beam splitter , facade beam splitter, beam splitter grating, semiconductor laser LD, mirror, cylindrical mirror, four-quadrant detector, light guide fiber, focusing mirror, dichroic mirror and two-dimensional position sensitive detector PSD. The test module includes a two-dimensional microscopic imaging measurement module for measuring the shape of the article, a Z-axis distance sensing module for measuring the height of the article in the Z-axis direction, and a sensor for the X-Y plane angle of the article to realize the space position. The X-Y plane angle sensing module for posture positioning, and the X-Y plane angle sensing module is also connected to the omnidirectional vision platform. The invention improves detection precision.

Description

A test system for omnidirectional multi-sensing 3D optical probe

technical field

The invention relates to the technical field of vision measurement, in particular to a test system for an omnidirectional multi-sensing three-dimensional optical measuring head.

Background technique

Visual inspection is to use machines instead of human eyes for measurement and judgment. Visual inspection refers to converting the captured target into an image signal through machine vision products (that is, image capture device, divided into CMOS and CCD), and sending it to a dedicated image processing system. According to pixel distribution, brightness, color and other information, it is transformed into Digitized signals; the image system performs various operations on these signals to extract the characteristics of the target, and then controls the on-site equipment actions according to the results of the discrimination. It is primarily used in valuable mechanisms for production, assembly or packaging. It has inestimable value in the function of detecting defects and preventing defective products from being delivered to consumers, so it is widely used in the market, and with the development of visual measurement, two-dimensional images typified by image measuring instruments Measurement has been widely used and is becoming more and more complete, but the current visual measurement is measured through two-dimensional angles, resulting in relatively poor measurement accuracy for some three-dimensional measurement objects, and the measurement is not accurate enough. Adjusting the zoom manually leads to relatively complex measurements and therefore needs improvement.

Contents of the invention

The purpose of the present invention is to provide a comprehensive multi-sensing three-dimensional optical probe testing system in order to solve the above-mentioned deficiencies in the prior art. On the basis of the image measurement system, the Z-axis distance sensing and the X-Y plane angle sensing are skillfully combined, and with the help of the industrial intelligent omni-directional vision pan/tilt, the omni-directional on-site three-dimensional non-contact measurement of the workpiece is realized, and the realization based on automatic The three-dimensional shape measurement of the zoom principle can finally improve the measurement accuracy, measurement accuracy and greatly reduce the difficulty of measurement.

In order to achieve the above-mentioned purpose, a kind of all-round multi-sensing three-dimensional optical probe testing system designed by the present invention includes the use of microscope objective lens, LED lighting source, industrial CCD camera, infrared beam splitter, lens tube lens, more than one Collimating mirrors, beam splitters, vertical beam splitters, beam splitting gratings, semiconductor lasers LD, mirrors, cylindrical mirrors, four-quadrant detectors, light guide fibers, focusing mirrors, dichroic mirrors and two-dimensional position sensitive detectors A test module composed of PSD, the test module includes a two-dimensional microscopic imaging measurement module for measuring the shape of the article, a Z-axis distance sensing module for measuring the height of the article in the Z-axis direction, and a sensor for the X-Y plane angle of the article To realize the X-Y plane angle sensing module for space pose positioning, the X-Y plane angle sensing module is also connected to the omnidirectional vision platform, and the two-dimensional microscopic imaging module is composed of a microscopic objective lens, an LED lighting source and an industrial CCD camera The optical combination realizes that the white light emitted by the LED lighting source enters the microscopic objective lens through the first collimating mirror, the infrared beam splitter and the vertical beam splitting prism. After the dichroic prism, it is focused on the phase surface of the industrial CCD camera by the lens tube lens for two-dimensional imaging;

The Z-axis distance sensing module uses the laser emitted by the semiconductor laser LD to be divided into three beams by the splitting grating, that is, the 0-order light and the ±1-order diffracted light. At this time, the 0-order light is reflected by the beam splitter and the reflector , is collimated by the second collimator into a parallel beam, the parallel beam is reflected by the vertical dichroic prism and then enters the microscope objective lens, and then the beam reflected by the object to be measured returns to the beam splitter according to the original path, and then is focused by the cylindrical mirror On the four-quadrant detector, use the voltage signal output terminals of four A, B, C and D on the four-quadrant detector to output detection signals;

The X-Y plane angle sensing module uses the infrared laser light source on the side to emit laser light, and then uses the light guide fiber, the third collimating mirror and the focusing mirror to focus on the dichroic reflector, and the focal point and the microscope objective lens The focus coincides, and the dichroic reflector is located between the dichroic prism and the microscopic objective lens and has a positional relationship with the optical axis of 45°, so that the infrared laser is vertically reflected into the microscopic objective lens after passing through the dichroic reflector, and exits The parallel infrared laser beam is reflected back to the microscopic objective lens through the measured object, and then an infrared beam splitter located between the dichroic mirror and the microscopic objective lens is used to reflect the returned infrared laser beam to the two-dimensional position sensitive detector PSD Realize data measurement.

A band-rejection filter for filtering the laser light emitted by the semiconductor laser LD and preventing it from affecting white light imaging on the CCD is provided between the top of the facade dichroic prism and the barrel lens.

The microscopic objective lens is a non-contact laser scanning measuring head.

The central wavelength of the laser light emitted by the semiconductor laser LD is 650nm.

A test system for an all-round multi-sensing three-dimensional optical measuring head obtained by the present invention. The present invention is based on the establishment of a two-dimensional microscopic image measurement system based on a far-field correction long working distance microscopic objective lens, and the Z-axis distance sensor Ingenious combination of measurement and X-Y plane angle sensing, and with the help of industrial intelligent omnidirectional vision pan/tilt, realizes omnidirectional on-site 3D non-contact measurement of the workpiece, and realizes 3D shape measurement based on the principle of automatic zoom, and ultimately improves the measurement Precision, measurement accuracy and the difficulty of measurement are greatly reduced.

reference sign

Fig. 1 is the device connection diagram of the test module in the test system of a kind of all-round multi-sensing three-dimensional optical probe in embodiment 1;

Fig. 2 is a schematic module diagram of a test module of an omnidirectional multi-sensing three-dimensional optical measuring head in embodiment 1;

Fig. 3 is the normalized focus error signal test result in embodiment 1;

Fig. 4 is the test result of TFES and TNFES among the embodiment 1;

FIG. 5 is a schematic diagram of the focused beam of the microscope objective lens irradiating the inclined surface in Embodiment 1. FIG.

Among the reference signs: 1. Microscopic objective lens; 2. LED lighting source; 3. Industrial CCD camera; 4. Infrared beam splitter; 5. Collimating mirror; 5-1. First collimating mirror; 5-2. Two collimating mirrors; 5-3. The third collimating mirror; 6. Beam splitter; 7. Facade beam splitting prism; 8. Beam splitting grating; 9. Semiconductor laser LD; .Four-quadrant detector; 13. Light guide fiber; 14. Focusing mirror; 15. Dichroic mirror; 16. Two-dimensional position-sensitive detector PSD; 17. Two-dimensional microscopic imaging measurement module; 18. Z-axis distance Sensing module; 19. X-Y plane angle sensing module; 20. Band-stop filter; 21. Lens tube lens; 22. Omni-directional vision platform; 24. Infrared laser light source.

Detailed ways

Below in conjunction with embodiment the invention is described preferably.

Example 1:

As shown in Fig. 1-Fig. 2, the testing system of a kind of all-round multi-sensing three-dimensional optical measuring head provided by this embodiment includes the use of microscope objective lens 1, LED lighting source 2, industrial CCD camera 3, infrared beam splitter 4 , barrel lens 21, more than one collimating mirror 5, beam splitter 6, facade beam splitting prism 7, beam splitting grating 8, semiconductor laser LD9, reflector 10, cylindrical mirror 11, four-quadrant detector 12, light guide fiber 13. A test module composed of a focusing mirror 14, a dichroic mirror 15 and a two-dimensional position sensitive detector PSD16, the test module includes a two-dimensional microscopic imaging measurement module 17 for measuring the shape of an item, and a Z The Z-axis distance sensing module 18 for axial height measurement, the X-Y plane angle sensing module 19 for spatial pose positioning by sensing the X-Y plane angle of the item, and the X-Y plane angle sensing module 19 is also connected with the omnidirectional vision platform 22 connect,

The two-dimensional microscopic imaging measurement module 17 is an optical combination that utilizes the microscopic objective lens 1, the LED lighting source 2 and the industrial CCD camera 3 to realize that the white light emitted by the LED lighting source 2 passes through the first collimating mirror 5-1, the infrared The beam splitter 4 and the vertical beam splitting prism 7 enter the microscopic objective lens 1, and the light beam focused by the microscopic objective lens 1 is reflected back by the surface to be tested, and after passing through the vertical beam splitting prism 7, it is focused by the barrel lens 21 to the industrial CCD camera 3 on the phase surface for two-dimensional imaging;

The Z-axis distance sensing module 18 uses the laser light emitted by the semiconductor laser LD9 to be divided into three beams by the splitting grating 8, that is, the 0-order light and the ±1-order diffracted light. At this time, the 0-order light passes through the beam splitter 6 and the reflector After the reflection of 10, it is collimated into a parallel beam by the second collimating mirror 5-2, and the parallel beam enters the microscopic objective lens 1 after being reflected by the vertical dichroic prism 7, and then the beam reflected by the object to be measured returns to the The beam splitter 6 is then focused onto the four-quadrant detector 12 through the cylindrical mirror 11, and utilizes four voltage signal output terminals of A, B, C and D on the four-quadrant detector 12 to output detection signals;

The X-Y plane angle sensing module 19 utilizes the infrared laser light source 24 on the side to emit laser light, and then focuses on the dichroic reflector 15 using the light guide fiber 13, the third collimating mirror 5-3 and the focusing mirror 14 , and the focal point coincides with the focal point of the microscopic objective lens 1, and the dichroic reflector 15 is positioned between the vertical dichroic prism 7 and the microscopic objective lens 1 and has a positional relationship of 45° with the optical axis, so that through the dichroic reflection After the mirror 15, the infrared laser is vertically reflected into the microscopic objective lens 1, and the outgoing parallel infrared laser beam is reflected back to the microscopic objective lens 1 through the object to be measured, and then a mirror located between the dichroic mirror 15 and the microscopic objective lens 1 is used to The infrared beam splitter 4 reflects the returned infrared laser beam to the two-dimensional position sensitive detector PSD16 to realize data measurement.

Between the top of the vertical dichroic prism 7 and the barrel lens 21, there is a band-stop filter 20 which filters out the laser light emitted by the semiconductor laser LD9 to prevent it from affecting white light imaging on the CCD.

The microscopic objective lens 1 is a non-contact laser scanning measuring head.

The center wavelength of the laser light emitted by the semiconductor laser LD9 is 650nm.

In this implementation, since the output of the four-quadrant detector 12 is a weak voltage signal, it is necessary to install a signal amplification circuit behind the four-quadrant detector 12, and the amplified output voltage signal can be correspondingly recorded as U _A , U _B , U _C and U _D , so the focus error signal is FES=(U _A +U _C )-( _UB + _UD ), and the normalized focus error signal is NFES=[(U _A +U _C )-( _UB +U _D )]/(U _A +U _B +U _C + _UD ).

Because the focal lengths of the cylindrical mirror 11 are different in the meridional direction and the sagittal direction, the focusing spot falling on the four-quadrant detector 12 introduces a geometric aberration, which is called astigmatism; When the focal plane is at the position, that is, the defocus displacement Δd=0, the focusing spot on the four-quadrant detector 12 is circular, and FES=0; are ellipses whose directions are perpendicular to each other, FES>0 and FES<0 respectively.

Taking the distance Δd between the surface of the measured object and the focal plane of the microscope objective lens 1 as the horizontal axis, and taking the focus error signal FES or normalized focus error signal NFES as the vertical axis, the S-curve of the astigmatic autofocus system is obtained, and the zero point of the curve is The position is the position of accurate focus, and the middle section of the curve has a good linear relationship, which can be used to measure the displacement of the surface of the measured object in the Z-axis direction, as shown in Figure 3.

In actual measurement, due to the non-monotonicity of FES and NFES curves, the position of the target object will be uncertain. In Fig. 4, however, when FES is at the zero crossing, the sum signal SS reaches a maximum value, and the shape of the SS curve is symmetrical about the maximum value. According to this characteristic, a threshold can be set in the sum signal SS to truncate FES and NFES to make it monotonic. If the sum signal SS is greater than the threshold, a gate signal GS is set to logic true (ie high voltage value); otherwise, it is set to logic false.

After FES and NFES are logically ANDed by the gate signal GS, a truncated focus error signal TFES and a truncated normalized focus error signal TNFES are obtained. The test results are shown in FIG. 3 .

During the operation of the X-Y plane angle sensing module 19, in order to avoid the mutual influence of the beam for autofocus and the beam for sensing inclination, the measuring head uses a red laser as a light source for autofocus, and uses an infrared laser as a light source for sensing inclination. Therefore, the probe uses finite far-infrared apochromatically corrected microscope objectives that are chromatically corrected for the visible to near-infrared band.

As shown in Figure 5, if the surface of the measured object has an inclination angle in the Y direction, the reflected infrared laser beam will have a position change in the Y direction of the two-dimensional PSD; similarly, if the measured object surface has an inclination angle in the X direction If the inclination angle is different, the reflected infrared laser beam will also change its position in the X direction of the two-dimensional position sensitive detector PSD16. Therefore, any inclination angle on the surface of the measured object can be sensed by the position of the light spot on the two-dimensional position sensitive detector PSD16.

The space pose positioning during the operation of the X-Y plane angle sensing module 19, the space pose positioning function of the probe is based on the X-Y plane angle sensing function, and is realized by means of the omnidirectional vision platform 22. As can be seen from the above, The X-Y plane angle sensing function module and the omnidirectional vision platform 22 can form a closed-loop adjustment mechanism for space pose correction of the in-situ optical measuring head. The basic workflow of spatial pose positioning includes the following steps:

The first step is to sense the inclination of the measured surface of the workpiece;

In the second step, the measured value is sent to the omnidirectional vision platform 22, and its movement is controlled to drive the spatial posture of the measuring head to change, so that the optical axis tends to be perpendicular to the surface to be measured;

In the third step, because the working distance between the probe and the surface to be measured changes, it is necessary to perform the autofocus operation again.

In actual work, it is often necessary to execute the above workflow several times. In addition, if you want to realize all-round in-situ 3D non-contact measurement of the workpiece, then use the intelligent guidance of the CAD model of the workpiece to quickly guide the probe to the target position according to the position parameters of the measured features provided by the CAD model, and initially determine the position. posture.

The present invention is based on the establishment of a two-dimensional microscopic image measurement system based on the far-field correction long working distance microscopic objective lens, and cleverly combines the Z-axis distance sensing and the X-Y plane angle sensing, and uses industrial intelligent omnidirectional vision The pan/tilt realizes all-round on-site three-dimensional non-contact measurement of the workpiece, and realizes three-dimensional shape measurement based on the principle of automatic zoom, which ultimately improves the measurement accuracy, measurement accuracy and greatly reduces the difficulty of measurement.

The basic principles and main features of the present invention and the advantages of the present invention have been shown and described above. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and without departing from the spirit or basic principles of the present invention. The present invention can be implemented in other specific forms without any specific features. Accordingly, the embodiments should be regarded in all points of view as exemplary and not restrictive, the scope of the invention being defined by the appended claims rather than the foregoing description, and it is therefore intended that the scope of the invention be defined by the appended claims rather than by the foregoing description. All changes within the meaning and range of equivalents of the elements are embraced in the present invention. Any reference sign in a claim should not be construed as limiting the claim concerned.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (5)

1. a kind of test system of comprehensive more sensing three-dimensional optical gauge heads, it is characterised in that：Including the use of microcobjective (1), LED illumination light source (2), industrial CCD camera (3), infrared beamsplitter (4), tube lens (21), more than one collimating mirror (5), Spectroscope (6), facade Amici prism (7), spectro-grating (8), semiconductor laser LD (9), speculum (10), cylindrical mirror (11), 4 quadrant detector (12), light-conductive optic fibre (13), focus lamp (14), dichroic mirror (15) and two-dimensional position-sensitive The test module of detector PSD (16) compositions, the test module include that the two-dimentional micro-imaging of topography measurement is carried out to article Measurement module (17) carries out article the Z axis distance sensing module (18) of Z-direction elevation carrection, to the X-Y plane angle of article Degree sensing come realize spatial pose positioning X-Y plane angle sensing modules (19), X-Y plane angle sensing modules (19) also with Omni-directional visual platform (22) connects,

The two dimension micro-imaging measurement module (17) is to utilize microcobjective (1), LED illumination light source (2) and industrial CCD phase The optical combination that machine (3) is constituted realizes that the white light that LED illumination light source (2) is sent out passes through the first collimating mirror (5-1), infrared spectroscopy Mirror (4) and facade Amici prism (7) enter microcobjective (1), and the light beam after microcobjective (1) focusing is anti-by surface to be measured It is emitted back towards and, after facade Amici prism (7), the upper progress of practising physiognomy of industrial CCD camera (3) is focused on by tube lens (21) Two-dimensional imaging；

The Z axis distance sensing module (18) is that the laser sent out using semiconductor laser LD (9) is split grating (8) point At three light beams, i.e. 0 grade of light and ± 1 order diffraction light, 0 grade of light is by the anti-of spectroscope (6) and speculum (10) at this time After penetrating, collimated light beam is collimated by the second collimating mirror (5-2), which enters after facade Amici prism (7) reflection Microcobjective (1) then then passes through cylindrical mirror by the light beam of object under test reflection according to backtracking to spectroscope (6) (11) it focuses on 4 quadrant detector (12), the voltage signal using four A, B, C and D on 4 quadrant detector (12) is defeated Outlet output detection signal；

The X-Y plane angle sensing modules (19) are to send out laser using the infrared laser light source (24) of side, then sharp Focused on dichroic mirror (15) with light-conductive optic fibre (13), third collimating mirror (5-3) and focus lamp (14), and the focus with The focus of microcobjective (1) overlaps, using dichroic mirror (15) be located at facade Amici prism (7) and microcobjective (1) it Between and the position relationship at 45 ° with optical axis so that infrared laser is vertically reflected into after dichroic mirror (15) aobvious In speck mirror (1), the parallel infrared laser beam of outgoing is reflected back microcobjective (1) by testee, then using positioned at two The infrared laser beam of return is reflected into two to an infrared beamsplitter (4) between color speculum (15) and microcobjective (1) DATA REASONING is realized on dimension Position-Sensitive Detector PSD (16).

2. a kind of test system of comprehensive more sensing three-dimensional optical gauge heads according to claim 1, which is characterized in that Being equipped between the top and tube lens (21) of facade Amici prism (7) will be filtered by the laser that semiconductor laser LD (9) are sent out It removes, the band resistance filter (20) for avoiding it from being impacted to white light imaging on CCD.

3. a kind of test system of comprehensive more sensing three-dimensional optical gauge heads according to claim 1, which is characterized in that institute The microcobjective (1) stated is non-contact laser scanning feeler.

4. a kind of test system of comprehensive more sensing three-dimensional optical gauge heads according to claim 1 or 2, feature exist In the centre wavelength 650nm for the laser that the semiconductor laser LD (9) sends out.

5. a kind of test system of comprehensive more sensing three-dimensional optical gauge heads according to claim 3, which is characterized in that institute State the centre wavelength 650nm for the laser that semiconductor laser LD (9) is sent out.