CN110186653B - Optical axis consistency calibration and split image fixed focus adjustment device and method for non-imaging system - Google Patents
Optical axis consistency calibration and split image fixed focus adjustment device and method for non-imaging system Download PDFInfo
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- CN110186653B CN110186653B CN201910455989.8A CN201910455989A CN110186653B CN 110186653 B CN110186653 B CN 110186653B CN 201910455989 A CN201910455989 A CN 201910455989A CN 110186653 B CN110186653 B CN 110186653B
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Abstract
The device comprises an attenuation system, a telescopic system, a quarter wave plate, a polarization splitting prism, a polarizer, an off-axis total reflection type optical fiber collimating mirror, an FC (fiber channel) optical fiber interface, a wide spectrum illumination light source, an all-dielectric interference filter, a primary imaging objective lens, a split image extraction and insertion device, a parallel flat plate, a split image focusing screen, a secondary imaging mirror group, a near infrared detector and a data processing system; the large-caliber telescopic system and the light path arrangement ensure that the posture of the device and the equipment to be tested is unchanged; the near infrared detector ensures the consistency of the measuring background; the wide-spectrum illumination light source arranged on the basis can emit full-aperture parallel light through the device, and is suitable for optical axis consistency measurement and adjustment of a non-imaging optical system within the aperture of the device.
Description
Technical Field
The invention belongs to the field of optical detection, and particularly relates to a device and a method for optical axis consistency calibration and split image fixed focus adjustment of a non-imaging system.
Background
With the development of optical sensing technology, the current sophisticated optoelectronic devices tend to be more and more complicated, and generally, large-scale optoelectronic devices are often composed of a plurality of optical subsystems. The whole device basically measures the same target, so that the consistency of optical axes of all systems of the device is ensured, and the premise that the detector is arranged on the optimal imaging surface to ensure the normal operation of the photoelectric device is met. For non-imaging optical systems such as a long-distance laser ranging system, a laser radar system, a space optical communication system and the like, non-imaging photoelectric detectors such as APDs and the like are utilized at a receiving end, the image processing capability is not available, and the functions of light spot position judgment and alignment cannot be realized, so that the optical axis consistency calibration is difficult to realize. At present, for the optical axis consistency adjustment of such optical systems, a common detection method needs a detection device to perform position adjustment for multiple times according to a certain rule or step length, the determination of an optical axis range is realized through the energy response of a detector, multiple groups of data are analyzed to calculate the specific position of a certain imaging point, and finally the optical axis deviation of a receiving axis and an aiming axis is obtained. Therefore, the problems of reduced precision and complicated detection process caused by the increase of error sources are the problems to be solved at present.
Chinese patent publication No.: the invention discloses a CN108508432A patent name of a portable optical axis detector and a method, and the detection steps of a transmitting shaft, a receiving shaft and a visible light shaft of a laser range finder are as follows, wherein the visible light shaft is aligned with the detector, and light emitted by the transmitting shaft is received by a CCD detector of the detector. And thirdly, the analog light source irradiates the APD detector at the receiving end, and the reflected light of the APD detector is received by the CCD detector of the detector. And processing the light spot data to obtain the optical axis parallelism deviation. The simulated light source is arranged in the laser range finder to be detected, so that the step of modifying equipment to be detected is added, and the detection process is complex. The simulated light source of the device is a 1064nm laser diode, and the light source has high temporal coherence and spatial coherence. A layer of protective glass is arranged on the APD detector, interference fringes can be generated on the front surface and the rear surface of the protective glass, and the interpretation of the CCD on the APD image position is influenced. The detection device is a system with short focal length and small caliber, and an oblique square prism is additionally adopted, so that the measurement precision is further reduced due to the limitation of the processing precision. Therefore, this invention cannot be used for the optical axis coincidence detection of a high-precision non-imaging optical system.
For defocus detection, a pinhole method, an astigmatism method, a foucault knife edge method, a critical angle method, and the like are commonly used at present. The method for quantitatively detecting the defocusing amount needs to build a complex test light path, is difficult to adjust, and is not suitable for online accurate measurement of products. The method in the prior art cannot be fused with parallelism detection equipment, and cannot realize simultaneous detection of the parallelism and the axial measurement.
Disclosure of Invention
The invention provides a device and a method for calibrating optical axis consistency and adjusting split image fixed focus of a non-imaging optical system, aiming at solving the problem that the prior art can not be applied to the optical axis consistency calibration of a high-precision non-imaging optical system. Meanwhile, the invention can realize the accurate on-line measurement of the defocusing amount of the optical equipment.
The technical scheme of the invention is as follows:
the device is characterized by comprising an attenuation system, a telescopic system, a quarter wave plate, a polarization splitting prism, a polarizer, an off-axis total reflection type optical fiber collimating mirror, an FC (fiber channel) optical fiber interface, a wide spectrum illumination light source, an all-dielectric interference light filter, a primary imaging objective lens, a split image extraction and insertion device, a parallel flat plate, a split image focusing screen, a secondary imaging mirror group, a near infrared detector and a data processing system; the attenuation system is arranged behind the transmitting end of the equipment to be tested and in front of the receiving aperture of the remote system; the telescope system, the quarter-wave plate, the polarization beam splitter prism, the primary imaging objective lens, the secondary imaging lens group and the near-infrared detector are coaxially arranged in sequence; the parallel flat plate and the split image focusing screen are arranged on the split image plugging device; the split image extraction and insertion device is arranged at the position of an image space focal plane of the primary imaging objective lens, and the parallel flat plate and the split image focusing screen are respectively positioned on the coaxial optical axes in the extraction and insertion processes; the polarizer and the off-axis total reflection type optical fiber collimating mirror are sequentially arranged in a reflection light path of the polarization beam splitter prism; the wide-spectrum illumination light source is connected with an FC optical fiber interface through a multimode optical fiber, the all-dielectric interference filter is placed at the front end of the illumination light source, and the FC optical fiber interface is arranged at the focus position of the off-axis total reflection type optical fiber collimating mirror; the data processing system is connected with the near-infrared detector through a data line; the near infrared detector is positioned at the image space focal plane of the secondary imaging lens group;
when the transmitting end of the device to be detected transmits laser, the light beam passes through the attenuation system, the attenuated light beam enters the telescope system, is reflected by the primary mirror and the secondary mirror in the telescope system and then is emitted, the emergent light passes through the quarter-wave plate and is changed into linearly polarized light in a P-wave form, and then the P light passes through the polarization beam splitter prism, the primary imaging objective lens, the split image extraction and insertion device and the secondary imaging mirror group in sequence and finally converges on the near infrared detector;
when the wide-spectrum illumination light source is turned on, light beams pass through the all-dielectric interference filter, then are emitted from the FC optical fiber interface and irradiate onto the off-axis total reflection type optical fiber collimating mirror, reflected parallel light passes through the polarizer and is changed into S wave, the S wave is reflected in the polarization splitting prism, then is changed into circularly polarized light through the quarter wave plate, and finally is emitted from the telescopic system and irradiates the visual aiming end of the equipment to be tested and the APD detector of the receiving end;
the light diffusely reflected by the APD detector at the receiving end of the device to be detected passes through the telescope system again, the circularly polarized light passes through the quarter wave plate and then becomes P light, and the P light can penetrate through the polarization beam splitter prism, then sequentially pass through the primary imaging objective lens, the split image extraction and insertion device and the secondary imaging lens group, and finally is received by the near infrared detector.
The optical axis consistency calibration and split image fixed focus adjustment method of the non-imaging system comprises the following steps:
firstly, turning on a broad spectrum illumination light source, removing an all-dielectric interference filter, preliminarily aligning to the tested equipment and a detection device, observing at a visual aiming end of the tested equipment, continuously adjusting the position of the tested equipment until the visual aiming end can observe a light spot image emitted by the illumination light source, and adjusting to the central position of a view field to serve as a visual reference axis in the whole test process;
step two, turning off the broad spectrum illumination light source, placing an attenuation system behind the emission end of the tested equipment, turning on the emission end of the tested equipment, adjusting the attenuation sheet group, and ensuring that light spots displayed by the data image processing system are clear and the light intensity is moderate;
thirdly, after a switch of an emission end of the tested device is turned on, emergent laser passes through an attenuation system, then passes through a telescopic system, and finally converges on a near-infrared detector after passing through a quarter-wave plate, a polarization beam splitter prism, a primary imaging objective lens, a parallel flat plate and a secondary imaging lens group; the near-infrared detector is connected with a computer through a data line, a data image processing program of the computer can display a light spot image and calculate the coordinates of the center position of a light spot at the transmitting end, namely the position coordinates of a transmitting shaft, and the deviation value A of the position of the light spot and a visual reference;
turning off a switch of an emission end of the tested equipment, turning on a switch of a broad-spectrum illumination light source, and placing an all-dielectric interference filter at the front end of the illumination light source; light beams are filtered by an all-dielectric interference filter, then are emitted from an off-axis reflective optical fiber collimator, and are changed into S light after passing through a polarizer, the S light is changed into circularly polarized light after being reflected in a polarization beam splitter prism through a quarter wave plate, and finally is emitted from a telescopic system to illuminate an APD detector at a receiving end of a system to be detected, the light reflected in a diffused manner enters the telescopic system again, and is changed into P light after passing through the quarter wave plate, the P light enters a subsequent optical system through PBS and is finally imaged on a near infrared detector, a data processing system processes a light spot image received by the near infrared detector, and calculates the central position coordinate of the image at the moment, namely the position coordinate of a receiving shaft and a deviation value B from a visual standard, and simultaneously calculates a deviation value C between the position coordinate of the receiving shaft and the position coordinate of an emission shaft in step; in conclusion, by using the deviation value C of the image center positions of the transmitting end and the receiving end and the deviation value A, B of the image center positions of the transmitting end and the receiving end and the visual reference respectively, and combining the system focal length, the angle deviation among the transmitting shaft, the visual aiming shaft and the receiving shaft can be calculated, and the detection process of the consistency of all optical axes of the tested equipment is completed;
step five, keeping the emission end of the tested equipment in the step four closed, and turning on the broad spectrum illumination light source; only adjusting the split image plugging device to make the split image focusing screen in a common optical axis state, when the APD detector at the receiving end of the equipment to be tested diffusely reflects back light, as long as the imaging has out-of-focus amount, the image can be displayed as a staggered circular spot or a staggered APD detector image in the computer, and the computer data processing system can be represented by a split image out-of-focus relation according to the deviation of the central position of the staggered image:
Δ1＝0.02055D＝0.000411S
calculating the magnitude delta of defocus1(ii) a According to the magnitude delta of defocus1And the position of the APD detector at the receiving end of the device to be tested is moved back and forth, so that the device to be tested can be ensured to be arranged at an ideal image surface position, and the split image fixed-focus assembling and adjusting process is completed.
The invention has the beneficial effects that:
1. the large-caliber telescopic system and the light path arrangement ensure that the postures of the device and the equipment to be measured are unchanged when the positions of light spots at the transmitting end and the receiving end of the equipment to be measured are respectively measured. The near infrared detector is equivalent to time-sharing reception of the light spot image, namely consistency of the measurement background is guaranteed. On the basis, the wide-spectrum illumination light source arranged can emit full-aperture parallel light through the device, near-infrared wavelength illumination of the non-imaging optical system is realized, a near-infrared detector can receive a light spot image in real time, and interference of visible light on a test result is avoided, so that the device is suitable for optical axis consistency measurement and adjustment of the non-imaging optical system within the aperture of the device.
The front end of the illumination light source with the wide spectrum is provided with the all-dielectric interference filter, the transmission spectrum bandwidth is certain, the time coherence and the space coherence are greatly reduced, the light source can be changed into quasi-monochromatic light with the wavelength suitable for the equipment to be tested, and compared with a laser light source with good space coherence and time coherence, the interference fringes formed on the front surface and the rear surface of protective glass of an APD detector can be eliminated, and the precision of judging the image central point by a computer is improved.
The equipment adopts a large-caliber long-focus telescopic system, and can improve the sensitivity of optical axis deviation.
And all light beams in the measuring process pass through the same main channel, and data calculation is also carried out under the same coordinate system, so that the coordinate conversion process is omitted, and error sources are reduced. Finally, the device is subjected to a precision test experiment of single position measurement, and the uncertainty of the optical axis consistency measurement is better than 1'. Therefore, the device realizes high-precision measurement of the consistency of the optical axis of the non-imaging optical system.
2. The wide-spectrum illumination light source is arranged in the detection device, the non-imaging detector and the aiming end of the receiving end of the detected device in a non-working state can be illuminated without changing the detected device, and light beams reflected by the non-imaging detector can pass through the telescopic system and are received by the device to display images of the non-imaging detector, so that the wide-spectrum illumination light source is suitable for detecting the consistency of the optical axes of the non-imaging optical system.
After the alignment of the aiming end of the equipment to be tested is finished, the consistency of the optical axis of the high-precision equipment can be dynamically measured only by controlling the light source switch, and the testing process is simple and convenient.
The lighting light path and the testing light path of the device have the same path, so that the structure of the device is simplified.
And the illumination light source of the device can not only illuminate the receiving end detector, but also can be used as a light source target in the test to realize the alignment function.
3. The device is provided with a split image focusing screen at the focal plane of a primary imaging objective lens.
By using the active light source illumination scheme, the defocusing detection of the detector can be performed when the imaging or non-imaging optical system does not work.
The split image focusing screen has high alignment precision, and the device has high defocusing detection precision by combining the magnification relation of the system.
And on the basis of optical axis consistency detection, the split image focusing screen is adjusted to be in a public optical axis state. The defocusing amount of the detector can be displayed in real time, and the axial position of the detector at the receiving end can be adjusted and corrected. Simple structure principle and convenient operation.
Drawings
FIG. 1 is a schematic structural diagram of a non-imaging multi-optical axis uniformity calibration and split image fixed focus adjustment device.
Wherein: 1. the device to be tested comprises 1-1 parts of equipment to be tested, an emission end, 1-2 parts of a visual aiming end, 1-3 parts of a receiving end, 2 parts of an attenuation system, 3 parts of a telescopic system, 4 parts of a quarter wave plate, 5 parts of a polarization splitting Prism (PBS), 6 parts of a polarizer, 7 parts of an off-axis total reflection type optical fiber collimating mirror, 8 parts of an FC optical fiber interface, 9 parts of a wide spectrum illumination light source, 10 parts of an all-dielectric interference filter 11, a primary imaging objective lens, 12 parts of a split image extraction and insertion device, 13 parts of a parallel flat plate, 14 parts of a split image focusing screen, 15 parts of a secondary imaging mirror group, 16 parts of a near infrared detector, 17 parts of a.
Fig. 2 is a schematic structural diagram of the split image focusing screen according to the present invention.
Fig. 3 is a light spot display diagram of the split image focusing screen of the present invention, wherein: FIG. 3a shows the complete circular spot on the split focusing screen when the lens is not out of focus, and FIG. 3b shows the staggered circular spot on the split focusing screen when the lens is out of focus.
Detailed Description
The technical scheme of the invention is described in detail in the following with reference to the accompanying drawings.
As shown in fig. 1, the device for optical axis consistency calibration and split image fixed focus adjustment of a non-imaging optical system comprises an attenuation system 2, a telescopic system 3, a quarter wave plate 4, a Polarization Beam Splitter (PBS)5, a polarizer 6, an off-axis total reflection type optical fiber collimator 7, an FC optical fiber interface 8, a wide spectrum illumination light source 9, an all-dielectric interference filter 10, a primary imaging objective lens 11, a split image extraction and insertion device 12, a parallel flat plate 13, a split image focusing screen 14, a secondary imaging mirror group 15, a near infrared detector 16 and a data processing system 17. The parallel flat plate 13 and the split focusing screen 14 are installed on the split image extraction and insertion device 12.
The attenuation system 2 is arranged behind the transmitting end of the device to be tested 1 and in front of the receiving aperture of the far-looking system 3. The telescope system 3, the quarter-wave plate 4, the polarization beam splitter prism 5, the primary imaging objective lens 11, the secondary imaging mirror group 15 and the near-infrared detector 16 are coaxially arranged in sequence. The split image extraction and insertion device 12 is installed at the position of the image space focal plane of the primary imaging objective lens 11, and in the extraction and insertion processes, the parallel flat plate 13 and the split image focusing screen 14 are respectively positioned on the optical axis. The polarizer 6 and the off-axis total reflection type optical fiber collimating mirror 7 are both arranged in the reflection light path of the polarization beam splitter prism 5. The wide-spectrum illumination light source 9 is connected with the FC optical fiber interface 8 through a multimode optical fiber, the all-dielectric interference filter 10 is placed at the front end of the illumination light source 9, and the FC optical fiber interface 8 is arranged at the focus position of the off-axis total reflection type optical fiber collimating mirror 7. The data processing system 17 is connected to the near-infrared detector 16 via a data line. The near infrared detector 16 is located at the image focal plane of the secondary imaging lens group 15.
When the emitting end 1-1 of the device to be detected 1 emits laser, the light beam passes through the attenuation system 2, the attenuated light beam enters the telescope system 3, is reflected by the primary mirror and the secondary mirror therein and then is emitted, the emergent light passes through the quarter wave plate 4 and is changed into P-wave-shaped linearly polarized light, and then the P light passes through the polarization beam splitter prism 5, the primary imaging objective lens 11, the split image extraction and insertion device 12 and the secondary imaging mirror group 15 in sequence and finally converges on the near infrared detector 16.
When a wide-spectrum illumination light source 9 is turned on, light beams are emitted from an FC optical fiber interface 8 after passing through an all-dielectric interference filter 10 and then irradiate on an off-axis total reflection type optical fiber collimating mirror 7, the reflected parallel light is changed into S wave after passing through a polarizer 6, the S wave is reflected in a polarization beam splitter prism 5, then is changed into circularly polarized light through a quarter wave plate 4, and finally is emitted from a telescopic system to irradiate APD detectors of a visual aiming end 1-2 and a receiving end 1-3 of the device to be tested 1.
The light diffusely reflected by the APD detector at the receiving end 1-3 of the device 1 to be detected passes through the telescopic system 3 again, the circularly polarized light passes through the quarter-wave plate 4 and then becomes P light, and the P light can pass through the polarization splitting prism 5, then sequentially pass through the primary imaging objective lens 11, the split image plugging device 12 and the secondary imaging mirror group 15, and finally is received by the near infrared detector 16.
The attenuation system 2 is an adjustable attenuation sheet group and is composed of three attenuation sheets with attenuation multiplying factors of 10, 100 and 1000 respectively. The models are OD1, OD2 and OD3 respectively. In order to prevent the laser intensity at the emitting end of the device to be tested 1 from being too high and damaging the near infrared detector 16, the combination of OD1, OD2 and OD3 is selected firstly. If the light spot received by the near infrared detector 16 is weak in brightness, the attenuation sheets are properly reduced, and the combination of the attenuation sheets is adjusted until the light spot is proper in brightness.
The telescope system 3 is a Cassegrain reflection telescope system, the light transmission caliber of which is 280mm, and the focal length of which is 1500 mm. The optical axes of the transmitting end 1-1, the aiming end 1-2 and the receiving end 1-3 of the tested device 1 are ensured to be in the same receiving caliber, so that the three optical axes of the tested device 1 are measured in the same background, and errors caused by data coordinate conversion do not exist. Under the same clear aperture, the longer the focal length is, the higher the coaxial detection precision of the system is, and the optical system with the focal length of 1500mm belongs to a long-focus system. Therefore, the device is suitable for detecting the consistency of the optical axis of high-precision equipment.
The half bandwidth of the transmission spectrum of the all-dielectric interference filter 10 is +/-20 nm. The light emitted by the broad spectrum light source 9 can be filtered into a quasi-monochromatic light source, the coherence of the light source is low, the wavelength requirement of the equipment to be tested can be met, and interference fringes generated on the front surface and the rear surface of APD protective glass of a non-imaging detector can be eliminated.
The split image plugging device 12 is provided with a split image focusing screen 14 and a parallel flat plate 13, when the parallel flat plate 13 is on a common optical axis, no split image effect exists, an image received by a near infrared detector 16 keeps integrity, and the position information of the image can be measured. When the split image focusing screen 14 is on the common optical axis, the split image effect is generated on the defocused image, and the split image effect is used for measuring the defocused amount information of the image.
As shown in fig. 2, the split image focusing screen 14 is formed by gluing two semicircular wedge-shaped flat plates with the same size, wherein the inclined angle of any one of the flat plates is 12 degrees, and the diameter of the flat plate is 20 mm.
The thickness of the intersection point of the centers of the two flat plates is 5 mm. The intersection point of the two flat plates of the split image focusing screen 13 is the ideal focal position of the optical system, and when the light beam convergence point is not defocused, the light spot received by the near infrared detector 16 is a complete circular spot, as shown in fig. 3 a. When the light beam convergence point is out of focus, the light spot received by the near infrared detector 16 is two staggered semicircular light spots, namely a split image, as shown in fig. 3 b.
The wavelength range of the near infrared detector 16 is 950-1700 nm, and the resolution is 640 multiplied by 512 pixels. For receiving the image of the spot entering the reflective telescopic system 3. And transmits the data to the image processing system 17 through a data line.
The image processing system 17 is a computer image processing program. The image received by the near infrared detector 16 is processed. The image processing system 17 can calculate the coordinates of the center position of the images and the center position deviations between different images, and thus the angular deviations of the different optical axes, given the focal length of the system. When the processing system processes the split image, the circle center position of the single semicircular light spot and the split image deviation D between the circle centers of the two semicircles can be identified. The focal point from an APD detector of the equipment to be tested to the split image screen can be obtained according to an axial magnification formula:
defocus delta at split-image focusing screen2Relationship to actual split image deviation y:
y＝2Δ2(n-1)
from the split image focusing screen focus to the near infrared detector, the vertical axis magnification formula shows that:
the split image deviation D received by the near infrared detector and the defocusing amount delta of the APD detector at the receiving end of the equipment to be tested1The relationship of (1) is:
wherein f is1Is the focal length, f, of the receiving end 1-3 of the system under test2Is the focal length of the telescopic system 3, n is the refractive index of the split image focusing screen 14, is the vertex angle degree of the inclined plane of the split image focusing screen, β is the vertical axis magnification of the secondary imaging lens group 15, and D is the split image deviation of the image received by the near infrared detector 16.
Combining the relation between the coordinate deviation S and the split image deviation D displayed by software and the actual parameters of the device, finally obtaining the defocusing amount delta of the APD receiving end of the receiving end 1-3 of the device to be tested and S1The split image defocus relation is as follows:
Δ1＝0.02055D＝0.000411S
in the actual adjusting process, the numerical value delta of the APD defocusing amount of the equipment to be measured can be calculated according to the coordinate deviation S displayed by the software1The axial positions of the APD detectors of the receiving ends 1-3 are finely adjusted from front to back until the imaging point is located at the ideal image surface, so that the function of auxiliary fixed-focus installation and adjustment can be realized.
The optical axis consistency calibration and split image fixed focus adjustment method of the non-imaging system comprises the following steps:
firstly, turning on a broad spectrum illumination light source 9, removing an all-dielectric interference filter 10, and preliminarily aligning the device to be detected 1 and a detection device. And observing at a visual aiming end 1-2 of the tested equipment, and continuously adjusting the position of the tested equipment until the visual aiming end 1-2 can observe a facula image emitted by the illumination light source and adjust to the central position of a visual field to be used as a visual reference axis in the whole testing process.
And step two, the broad spectrum illumination light source 9 is closed, and the attenuation system 2 composed of OD1, OD2 and OD3 is placed behind the emission end 1-1 of the tested device to prevent the emitted light intensity from being too high and damaging the near infrared detector 16. The transmitting terminal 1-1 of the device under test 1 is turned on. And the attenuation sheet group 2 is adjusted to ensure that light spots displayed by the data image processing system are clear and the light intensity is moderate.
And step three, after a switch of the emission end 1-1 of the tested device is turned on, the emergent laser passes through the attenuation system 2, then passes through the telescopic system 3, and then passes through the quarter-wave plate 4, the PBS5, the primary imaging objective lens 11, the parallel flat plate 13 and the secondary imaging lens group 15, and the split image focusing screen 14 is not in the common optical axis at the moment. The beam is finally focused on the near infrared detector 16. The near infrared detector 16 is connected to a computer through a data line, and a data image processing program 17 of the computer displays the light spot image. And calculating the position coordinates of the center of the light spot at the transmitting end, namely the position coordinates of the transmitting shaft, and the deviation value A of the position of the light spot and the visual reference.
And step four, turning off a switch of the emission end 1-1 of the tested equipment, turning on a switch of the broad spectrum illumination light source 9, and placing an all-dielectric interference filter 10 at the front end of the illumination light source 9. The light beam is filtered by the all-dielectric interference filter 10, then is emitted from the off-axis reflective optical fiber collimator 7, is changed into S light after passing through the polarizer 6, is reflected in the polarization beam splitter prism PBS5, is changed into circularly polarized light through the quarter-wave plate 4, and finally is emitted from the telescopic system 3 to illuminate the APD detectors of the receiving ends 1-3 of the system to be tested. The light reflected by the light source enters the telescope system 3, and then passes through the quarter-wave plate 4 to become P light, and the P light passes through the PBS to enter the subsequent optical system and finally forms an image on the near-infrared detector 16. The data processing system 17 processes the light spot image received by the near infrared detector, and calculates the center position coordinate of the image at the moment, namely the position coordinate of the receiving shaft and the deviation value B from the visual reference, and simultaneously calculates the deviation value C between the position coordinate of the receiving shaft and the position coordinate of the transmitting shaft in the step three; in summary, the deviation value C of the image center positions of the transmitting end and the receiving end and the deviation value A, B of the visual reference are utilized, and the angular deviation between the transmitting shaft, the visual aiming shaft and the receiving shaft can be calculated by combining the system focal length, so that the detection process of the consistency of each optical axis of the tested equipment is completed.
Step five, keeping the emission end 1-1 of the tested equipment in the step four closed, and turning on the broad spectrum illumination light source 9. Only the split image extraction and insertion device 12 is adjusted to enable the split image focusing screen 14 to be in a common optical axis state. When the APD detector at the receiving end 1-3 of the device to be tested diffusely reflects back light, as long as the image has a defocus amount, the image can be displayed as a staggered circular spot or a staggered APD detector image in the computer, and the computer data processing system 17 can calculate the defocus amount according to the deviation of the central position of the staggered image by the split image defocus relation. According to the defocusing amount, the position of the APD detector of the receiving end 1-3 of the equipment to be tested is moved back and forth, and the detector of the equipment to be tested can be guaranteed to be installed at an ideal image surface position. Thus, the process of split image fixed focus adjustment is completed.
The device of the invention has the following precision testing process:
the device is used for directly detecting different light spot position information and analyzing the result to obtain the single light spot position detection precision of the device.
The image acquisition of the device is high-frequency real-time acquisition, and the dynamic coordinates of the image position can be obtained. Therefore, a plurality of groups of coordinate data of a certain position are directly recorded, and data analysis is carried out, so that the detection precision of the light spot position of the device can be obtained. During the experiment, the position coordinates (x, y) of the light spot within 1 second are taken once, the data value of each position measurement is about 100 to 300 groups, 5 times of measurement are carried out, and the measurement results are shown in table 1.
TABLE 1
In table 1, the measured point deviation value is the square root of the sum of the squares of the standard deviations in the x and y directions for that point. Thereby characterizing the position measurement accuracy. The maximum measurement point position deviation value is 0.1460, which is calculated as follows;
i.e., a single measurement with a maximum angle error of 0.0001115 degrees, which is approximately 0.4014 ". The uncertainty of the single light spot position measurement of the device is better than 0.5 'and the uncertainty of the optical axis consistency measurement is better than 1' under the good experimental environment.
Claims (7)
1. The device is characterized by comprising an attenuation system (2), a telescopic system (3), a quarter wave plate (4), a polarization splitting prism (5), a polarizer (6), an off-axis total reflection type optical fiber collimating mirror (7), an FC (fiber channel) optical fiber interface (8), a wide spectrum illumination light source (9), an all-dielectric interference filter (10), a primary imaging objective lens (11), a split image extraction and insertion device (12), a parallel flat plate (13), a split image focusing screen (14), a secondary imaging mirror group (15), a near infrared detector (16) and a data processing system (17);
the attenuation system (2) is arranged behind the transmitting end of the equipment to be tested (1) and in front of the receiving aperture of the far-looking system (3);
the telescope system (3), the quarter-wave plate (4), the polarization beam splitter prism (5), the primary imaging objective lens (11), the secondary imaging lens group (15) and the near infrared detector (16) are coaxially arranged in sequence; the parallel flat plate (13) and the split image focusing screen (14) are arranged on the split image extraction and insertion device (12); the split image extraction and insertion device (12) is arranged at the position of an image focal plane of the primary imaging objective lens (11), and in the extraction and insertion processes, the parallel flat plate (13) and the split image focusing screen (14) are respectively positioned on the coaxial optical axes;
the polarizer (6) and the off-axis total reflection type optical fiber collimating mirror (7) are sequentially arranged in a reflection light path of the polarization beam splitter prism (5); the wide-spectrum illumination light source (9) is connected with an FC optical fiber interface (8) through a multimode optical fiber, the all-dielectric interference filter (10) is placed at the front end of the illumination light source (9), and the FC optical fiber interface (8) is arranged at the focus position of the off-axis total reflection type optical fiber collimating mirror (7); the data processing system (17) is connected with the near infrared detector (16) through a data line; the near infrared detector (16) is positioned at the image focal plane of the secondary imaging lens group (15);
when the transmitting end (1-1) of the device to be tested (1) transmits laser, the light beam passes through the attenuation system (2), the attenuated light beam enters the telescope system (3) and is reflected by the primary mirror and the secondary mirror in the telescope system to be emitted, the emergent light passes through the quarter wave plate (4) to be changed into P-wave linearly polarized light, and then the P light passes through the polarization beam splitter prism (5), the primary imaging objective lens (11), the split image extraction and insertion device (12) and the secondary imaging mirror group (15) in sequence and finally converges on the near infrared detector (16);
when a wide-spectrum illumination light source (9) is turned on, light beams pass through an all-dielectric interference filter (10), then are emitted from an FC (fiber channel) optical fiber interface (8) and irradiate onto an off-axis total reflection type optical fiber collimating mirror (7), reflected parallel light passes through a polarizer (6) and then is changed into S wave, the S wave is reflected in a polarization splitting prism (5), then is changed into circularly polarized light through a quarter-wave plate (4), and finally is emitted from a telescopic system to irradiate APD (avalanche photo diode) detectors) of a visual aiming end (1-2) and a receiving end (1-3) of equipment to be tested (1);
the light diffusely reflected by the APD detector of the receiving end (1-3) of the device to be tested (1) passes through the telescopic system (3) again, the circularly polarized light passes through the quarter-wave plate (4) and then becomes P light, the P light can penetrate through the polarization splitting prism (5), then passes through the primary imaging objective lens (11), the split image extraction and insertion device (12) and the secondary imaging mirror group (15) in sequence, and finally is received by the near infrared detector (16).
2. The optical axis consistency calibration and split image fixed focus adjustment device of the non-imaging optical system according to claim 1, wherein the attenuation system (2) is an adjustable attenuation sheet group and is composed of three attenuation sheets with attenuation multiplying powers of 10, 100 and 1000; the models are OD1, OD2 and OD3 respectively.
3. The optical axis consistency calibration and split image fixed focus adjustment device of the non-imaging optical system according to claim 1, wherein the telescope system (3) is a Cassegrain reflection telescope system, the clear aperture of which is 280mm, and the focal length of which is 1500 mm.
4. The optical axis uniformity calibration and split image fixed focus adjustment device of non-imaging optical system according to claim 1, wherein the transmission spectrum half bandwidth of said all-dielectric interference filter (10) is ± 20 nm.
5. The optical axis consistency calibration and split image fixed focus adjustment device of the non-imaging optical system according to claim 1, wherein the split image focusing screen (14) is formed by gluing two semicircular wedge-shaped flat plates with the same size, and the inclined plane of any one of the flat plates has an inclination angle of 12 degrees and a diameter of 20 mm.
6. The optical axis consistency calibration and split image fixed focus adjustment device of the non-imaging optical system according to claim 1, wherein the wavelength range of the near infrared detector (16) is 950-1700 nm, and the resolution is 640 x 512 pixels.
7. The method for optical axis consistency calibration and split image fixed focus adjustment of a non-imaging system using the device of claim 1, comprising the steps of:
firstly, turning on a broad spectrum illumination light source (9), moving away an all-dielectric interference filter (10), preliminarily aligning a tested device (1) and a detection device, observing at a visual aiming end (1-2) of the tested device, continuously adjusting the position of the tested device until the visual aiming end (1-2) can observe a light spot image emitted by the illumination light source and adjust to the center position of a view field to serve as a visual reference axis in the whole test process;
step two, closing the broad spectrum illumination light source (9), placing the attenuation system (2) behind the emission end (1-1) of the tested equipment, starting the emission end (1-1) of the tested equipment (1), adjusting the attenuation sheet group (2), and ensuring clear light spots displayed by the data image processing system and moderate light intensity;
step three, after a switch of an emission end (1-1) of the tested equipment is turned on, emergent laser passes through an attenuation system (2), then passes through a telescopic system (3), and then passes through a quarter-wave plate (4), a polarization beam splitter prism (5), a primary imaging objective lens (11), a parallel flat plate (13) and a secondary imaging mirror group (15), and light beams finally converge on a near-infrared detector (16); the near infrared detector (16) is connected with a computer through a data line, a data image processing program (17) of the computer displays a light spot image, and calculates the first light spot center position coordinate of the transmitting end (1-1), namely the position coordinate of a transmitting shaft, and the deviation value A of the light spot position and a visual reference;
turning off a switch of an emission end (1-1) of the tested equipment, turning on a switch of a broad spectrum illumination light source (9), and placing an all-dielectric interference filter (10) at the front end of the illumination light source; light beams are filtered by an all-dielectric interference filter (10), emitted from an off-axis reflective optical fiber collimator (7), changed into S light by a polarizer (6), reflected in a polarization beam splitter prism (5), changed into circularly polarized light by a quarter wave plate (4), emitted from a telescopic system (3), and used for illuminating an APD detector of a receiving end (1-3) of a system to be detected, the light reflected in a diffused manner enters the telescopic system (3), changed into P light by the quarter wave plate (4), transmitted by the polarization beam splitter prism (5), enters a subsequent optical system and finally imaged on a near infrared detector (16), a data processing system (17) processes a light spot image received by the near infrared detector, and calculates the central position coordinate of the image at the moment, namely the position coordinate of a receiving axis and a deviation value B from a visual reference, meanwhile, calculating a deviation value C between the position coordinate of the receiving shaft and the position coordinate of the transmitting shaft in the step three; in conclusion, the angle deviation among the transmitting shaft, the visual aiming shaft and the receiving shaft can be calculated by utilizing the deviation value C of the image center positions of the transmitting end (1-1) and the receiving end (1-3) and the deviation value A, B of the image center positions and the visual reference respectively and combining the system focal length, so that the process of detecting the consistency of all optical axes of the tested equipment is completed;
step five, keeping the emission end (1-1) of the tested equipment in the step four closed, and turning on the broad spectrum illumination light source (9); only adjusting the split image extraction and insertion device (12) to enable the split image focusing screen (14) to be in a common optical axis state, when the APD detector of the receiving end (1-3) of the device to be tested diffusely reflects back light, as long as the imaging amount is out of focus, the image can be displayed as a staggered circular spot or a staggered APD detector image in the computer, and the computer data processing system (17) can be represented by a split image out-of-focus relational expression according to the deviation of the central position of the staggered image:
Δ1＝0.02055D＝0.000411S
calculating the magnitude delta of defocus1According to the magnitude of defocus Δ1And the position of the APD detector at the receiving end (1-3) of the equipment to be tested is moved back and forth, so that the detector of the equipment to be tested can be ensured to be arranged at an ideal image surface position, and the split image fixed-focus assembly and adjustment process is completed.
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