阅读说明：本技术 能在测量中进行测量功能转换的激光测量装置及测试方法 (Laser measuring device capable of performing measurement function conversion during measurement and test method ) 是由 张涛 黄伟 尹伯彪 于 2019-09-29 设计创作，主要内容包括：本发明公开了能在测量中进行测量功能转换的激光测量装置,包括热稳频He-Ne激光器(1)、测量单元(16)、信号处理系统,热稳频He-Ne激光器(1)发出的光经过测量单元(16)后发送给信号处理系统,经处理得到测量结果,其特征在于,测量单元(16)中包括位置可变的反射镜(24)和遮光板(23)；当用于绝对测距功能时,靶镜(4)返回的光束经过反射镜(24)反射后,再经过偏振片(5)和雪崩管(6)；当用于绝对测距功能时,反射镜(24)改变位置,不位于靶镜(4)返回的光束的光路上,靶镜(4)返回的光束经过偏振片(11)由雪崩管(12)接收；遮光板(23)转换位置位于偏振分光镜(8)和角锥镜(10)之间,遮挡从偏振分光镜(8)透射光束的光路。(The invention discloses a laser measuring device capable of converting a measuring function in measurement, which comprises a thermal frequency stabilization He-Ne laser (1), a measuring unit (16) and a signal processing system, wherein light emitted by the thermal frequency stabilization He-Ne laser (1) is transmitted to the signal processing system after passing through the measuring unit (16) and is processed to obtain a measuring result, and the laser measuring device is characterized in that the measuring unit (16) comprises a position-variable reflecting mirror (24) and a light shielding plate (23); when the device is used for the absolute distance measurement function, the light beam returned by the target mirror (4) is reflected by the reflector (24) and then passes through the polaroid (5) and the avalanche pipe (6); when the device is used for the absolute distance measurement function, the reflector (24) changes the position and is not positioned on the light path of the light beam returned by the target mirror (4), and the light beam returned by the target mirror (4) is received by the avalanche pipe (12) through the polarizing plate (11); the switching position of the light shielding plate (23) is positioned between the polarizing beam splitter (8) and the conical mirror (10) and shields the light path of the light beam transmitted by the polarizing beam splitter (8).)

1. The laser measuring device capable of converting the measuring function in the measurement comprises a heat frequency stabilizing He-Ne laser (1), a measuring unit (16) and a signal processing system, wherein light emitted by the heat frequency stabilizing He-Ne laser (1) passes through the measuring unit (16) and then is sent to the signal processing system, and a measuring result is obtained through processing, and the laser measuring device is characterized in that the measuring unit (16) comprises a position-variable reflecting mirror (24) and a light shielding plate (23);

when the device is used for the absolute distance measurement function, the light beam returned by the target mirror (4) is reflected by the reflector (24) and then passes through the polaroid (5) and the avalanche pipe (6);

when the heat frequency stabilizing He-Ne laser is used for an absolute distance measuring function, the reflector (24) changes the position and is not positioned on the light path of a light beam returned by the target mirror (4), so that the light beam emitted by the heat frequency stabilizing He-Ne laser (1) is transmitted to the target mirror (4) through the beam splitter prism (3), and the polaroid (25) forms a measuring arm; the position of a light shielding plate (23) is changed, so that a light beam emitted by the heat frequency stabilization He-Ne laser (1) is reflected by a beam splitter prism (3) and then reaches a reflecting mirror (7), a polarization beam splitter (8) and an angle cone mirror (9) to form a reference arm; the light beam passing through the reference arm and the light beam passing through the measuring arm are converged and then received by the avalanche pipe (12) to form a measuring signal.

2. The laser measuring device capable of performing measurement function conversion during measurement according to claim 1, wherein the light shielding plate (23) and the reflecting mirror (24) are rotated under computer control to change positions.

3. The laser test method capable of performing measurement function conversion during measurement is characterized by comprising the following steps of:

s1, when the absolute distance measuring function is converted into the interference measuring function, the subsequent distance measuring value is the sum of the absolute distance measuring value before the function conversion and the subsequent precise interference measuring counting value;

s2: when the function is converted into the absolute ranging function from the interferometric function, the measurement starts with the last interferometric measurement data, and the subsequent distance measurement value is the sum of the precise interferometric value before the function conversion and the subsequent absolute ranging value.

Technical Field

The invention relates to the technical field of laser ranging, in particular to a laser measuring device and a laser measuring method capable of converting absolute ranging and interference measurement functions in measurement.

Background

The accurate measurement of the length and the contour shape of a large-size manufactured part is actually applied in ① Liguangyun mapping report 1998 (10) 'the latest progress of an industrial three-dimensional coordinate measuring system', an absolute distance measuring method is introduced, an industrial photoelectric measuring system which takes an electronic theodolite, a total station, a digital camera and the like as sensors can measure the measured distance at one time, and the accurate measurement method is characterized in that the technology is mature, the cost is low and the requirement on the use environment is low, but the accuracy is generally not high, a measured point needs to be preset with a cooperative target, the measurement can be carried out only point by point, the contour shape of a large-size workpiece cannot be measured by using a tracking technology, the contour measuring process is long and complicated.

From the above, it can be seen that the two practical application modes of precision measurement of the length and the outline shape of the large-size manufactured part have respective advantages and disadvantages, and the applicant has obtained the invention patent-the large-size part non-guide rail measuring device and the testing method thereof, wherein a high-precision absolute distance measuring system is disclosed, and the principle is shown in fig. 1. The measuring system is a novel measuring system which can measure the accurate distance without a guide rail and any large machine parts and only by aiming at a target lens at a measured point. The laser measuring system based on the absolute distance measuring technology not only brings great convenience to field operation because the laser beam is allowed to be shielded in the distance measuring process without influencing the measuring result, but also has wide application prospect in the fields of long-time monitoring and timing sampling measurement, such as framework deformation monitoring, seismic research and the like.

Therefore, the absolute distance measuring system is redesigned into a device capable of randomly converting the absolute distance measuring function mode and the interference measuring function mode in measurement, so that the device has the advantages of the precise measuring methods of the length and the outline shape of the two large-size manufactured parts, is quick and convenient to convert, and more importantly, lays a technical foundation for a laser tracker system with Chinese proprietary intellectual property rights.

Disclosure of Invention

The invention aims to provide a laser measuring device and a laser measuring method which can convert absolute distance measurement and interference measurement functions in measurement, and simultaneously have the advantages of two precise measuring methods for the length and the outline shape of a large-size manufactured part in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme:

the operation principle of the present invention is shown in fig. 2(a) and 2 (b). It is clear that, compared with the high-precision absolute ranging system shown in fig. 1, the positions of the 45 ° polarizer 5 and the avalanche pipe 6 for generating and outputting the node discrimination signal in the optical paths shown in fig. 2(a) and 2(b) are adjusted, and the direction is perpendicular to the original direction; at the same time, a position-variable reflector 24 and a light shielding plate 23 are additionally arranged, and the reflector and the light shielding plate are linked and can be controlled by a computer to act. The linkage mechanism has two positions, one position state is: the reflector 24 hangs down 45 degrees, and the shading plate 23 faces upwards; the other position state is: the mirror 24 is raised up to a horizontal position and the shutter 23 is lowered.

Specifically, the slide plate can be provided with a rotating mechanism, the reflector 24 and the light shielding plate 23 are both arranged on the rotating mechanism, and the computer controls the rotating mechanism to rotate, so that the reflector 24 and the light shielding plate 23 are controlled to change positions.

The absolute ranging function mode is the state shown in fig. 2 (a): the reflector 24 droops by 45 degrees and reflects the returned laser beam to the polarizing plate 5 and the avalanche pipe 6 which are installed by 45 degrees, and the light shielding plate 23 faces upwards and does not shield the light path. Laser beams emitted by the double longitudinal mode thermal frequency stabilized laser 1 are upwards reflected by the spectroscope 2 (with the transmittance of 80 percent), pass through the polaroid 13 arranged on the crystal axis at 45 degrees, so that vectors of the lasers with orthogonal polarization planes in the 45-degree direction are mutually interfered, and the avalanche tube 14 picks up reference signals required by frequency mixing. The beam splitter prism 3, the target mirror 4, the reflector 24, the polarizing plate 5 arranged at 45 degrees and the avalanche pipe 6 on the sliding plate form a light path for searching and judging the node position. The light reflected by the beam splitter prism 3 passes through a reflector 7, a polarization beam splitter 8, a pyramid 9, a pyramid 10 fixed outside the slide plate, a polarizing plate 11 installed at 45 degrees and a avalanche diode 12 to form an auxiliary interferometer. The distance from the measured point (the vertex of the target mirror 4) to the nearest node is automatically measured by the auxiliary interferometer. The reference and auxiliary interferometer measurement signals and the node discrimination signals output by the avalanche tube 14, the avalanche tube 12 and the avalanche tube 6 are respectively sent to a subsequent signal processing system, and absolute distance measurement results are obtained after processing. At the moment, the requirement of absolute ranging by beat frequency interference is completely met, and the whole optical path is a high-precision beat frequency absolute ranging system.

The interferometric functional mode is the state shown in fig. 2 (b): the mirror 24 is raised up to a horizontal position, the returning laser light passes to the beam splitter prism 3, and the light blocking plate 23 blocks the laser beam directed to the pyramid mirror 10 downward. Laser beams emitted by the double longitudinal mode thermal frequency stabilized laser 1 are upwards reflected by the spectroscope 2 (with the transmittance of 80 percent), pass through the polaroid 13 arranged on the crystal axis at 45 degrees, so that vectors of the lasers with orthogonal polarization planes in the 45-degree direction are mutually interfered, and the avalanche tube 14 picks up a reference signal required by the interferometer. The light beam transmitted by the spectroscope 2 is split by the spectroscope 3, and the reflected light forms a reference arm of a light path of the dual-frequency laser interferometer through the reflector 7, the polarization spectroscope 8 and the pyramid mirror 9; the light of the transmission part forms a measuring arm of a double-frequency laser interferometer light path through the target mirror 4 and the polaroid 25; the two paths of light are converged at the beam splitter prism 3, and vectors of the laser orthogonal to the polarization plane in the 45-degree direction are interfered with each other through a polaroid 11 arranged at a crystal axis in a 45-degree mode, and a avalanche tube 12 picks up a measurement signal required by an interferometer. And respectively sending the reference signal and the measurement signal to a subsequent signal processing system, and processing to obtain a precise interference measurement result. At the moment, the device is in a state when the dual-frequency laser interferometer works, and the whole optical path becomes a typical dual-frequency laser interferometer system.

When the absolute distance measurement is converted into the interference measurement, firstly, the reflector 24 and the light shielding plate 23 are turned to the position shown in fig. 2(b) according to the computer instruction, the distance value is obtained by adding the absolute distance measurement value before the function conversion and the numerical value of the precise interferometer, and one of the main purposes is to meet the requirement of using the laser tracking method for rapid profile measurement. On the contrary, when the interferometric measurement is converted into the absolute ranging, the reflector 24 and the light shielding plate 23 are firstly turned to the positions shown in fig. 2(a) according to the computer instructions, the measurement starts from the last interferometric measurement data, and the following automatic operation is completely the same as the absolute ranging. Specifically, when the absolute ranging function is converted into the interference measurement function, the subsequent distance measurement value is the sum of the absolute ranging value before the function conversion and the subsequent precise interference measurement count value; when the function is converted into the absolute ranging function from the interferometric function, the measurement starts with the last interferometric measurement data, and the subsequent distance measurement value is the sum of the precise interferometric value before the function conversion and the subsequent absolute ranging value.

It is worth to be noted that the high carrier frequency has no practical limit to the measurement speed in the precise interference measurement function mode, the light source frequency difference of the laser interferometer is the carrier frequency of the measurement system, the frequency difference of the double longitudinal mode laser light source of the invention is 780MHz, the maximum allowable moving speed can theoretically reach more than 150 m/s, and the frequency difference is not practical used so fast, because too fast, strong vibration and other problems can be caused.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention brings great convenience to the measurement of large-size parts, for example, when a certain section is measured and curved surface precise contour measurement is needed, the curved surface precise contour measurement is converted into smooth contour measurement with high resolution of the traditional laser interferometer through computer operation. All the fine-tuned critical components are not moved during the switching process, so that no new tuning of the beam path is required. Since the reference light is too strong (short path) in the conventional interferometer, the light loss at this time has no practical influence, and the conversion does not cause errors because the absolute distance measurement function allows the light beam to be blocked in the measurement interval.

(2) The interferometer can be converted and can be independently used as a distance meter or a dual-frequency interferometer, and has important significance for the universal applicability of high-value instruments.

Drawings

Fig. 1 is a schematic diagram of a high-precision absolute ranging system in the prior art.

Fig. 2(a) is an optical path diagram of the absolute distance measuring function mode of the device of the present invention.

FIG. 2(b) is an optical path diagram of the interferometer of the present invention.

Wherein the reference numerals are as follows:

the device comprises a 1 thermal frequency stabilizing He-Ne laser, 2 and 7 spectroscopes, 3 spectroscope prisms, 4 target mirrors, 5, 11, 13 and 25 polaroids, 6, 12 and 14 avalanche transistors, 8 polarizing spectroscopes, 9 and 10 pyramid mirrors, 15 sliding plates, 16 measuring units, 17 and 18 power dividers, 19 and 20 mixers, a 21 node identification circuit, a 22 computer, 23 shading plates and 24 reflectors.

Detailed Description

The present invention is further illustrated by the following figures and examples, which include, but are not limited to, the following examples.