CN107688172B - Multi-optical path cavity, detection device and detection method - Google Patents
Multi-optical path cavity, detection device and detection method Download PDFInfo
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- CN107688172B CN107688172B CN201710739407.XA CN201710739407A CN107688172B CN 107688172 B CN107688172 B CN 107688172B CN 201710739407 A CN201710739407 A CN 201710739407A CN 107688172 B CN107688172 B CN 107688172B
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- 238000012360 testing method Methods 0.000 abstract description 35
- 239000007788 liquid Substances 0.000 abstract 1
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Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
- G01S7/497—Means for monitoring or calibrating
Abstract
The invention relates to a multi-optical path cavity, a detection device and a detection method. A multiple optical path cavity, comprising: the incident light is reflected for multiple times and then emitted from the incident hole, the annular lens group comprises one or two annular spherical lenses, the incident hole is formed in one of the annular spherical lenses of the annular lens group, and the reflecting surface of the annular spherical lens is positioned on the inner side wall of the annular spherical lens. A kind of testing device, which is used to test the liquid, comprising the multi-optical path cavity. The detection method adopts the detection device to detect the optical ranging device to be detected. Through the cooperation of annular sphere mirror and entry hole and angle of incidence for incident light is regular polygon star and follows former entry hole and jets out in many optical path intracavity, under the prerequisite that reduces to occupy the test site, simulates the test environment that the optical ranging device that awaits measuring sent incident light to the test target, and receives the emission light after the reflection with less receiving angle.
Description
Technical Field
The invention relates to the technical field of radar quality detection and calibration, in particular to a multi-optical path cavity, a detection device and a detection method.
Background
At present, the range radar (the range can reach tens to hundreds meters) with longer range is mainly used for searching a corresponding long-distance test site indoors or outdoors, and the main defects are as follows: 1. each time, a large open field is needed to be found, so that the time and effort required by the test are increased; 2. for different product batches, the test conditions of a test space with a large area are difficult to be consistent, and standardized test and evaluation of the range radar are inconvenient; 3. environmental conditions such as sunlight, air temperature, water mist and the like are difficult to control, so that the industrial production is very unfavorable; 4. test conditions that differ significantly from the outdoor environment cannot be simulated.
Disclosure of Invention
The invention aims to provide a multi-optical path cavity, which enables incident light rays to be in a regular polygonal star shape in the multi-optical path cavity and to be emitted along an original incident hole through the matching of an annular spherical mirror, an incident hole and an incident angle, and simulates a test environment that an optical ranging device to be tested emits emitted light rays to a test target and receives reflected emitted light rays on the premise of reducing the occupied test field.
The invention aims to provide a detection device which realizes long-distance detection of an optical ranging device to be detected in a small test space through a multi-optical path cavity and a driving device, and is convenient to operate and accurate in test.
The invention aims to provide a detection method, which is used for adjusting the incidence angle of test light of an optical ranging device to be tested through a driving device, so that different long-distance measurement of the test light in a multi-optical path cavity is realized, the test space is reduced, and the test difficulty is reduced.
To achieve the purpose, the invention adopts the following technical scheme:
a multiple optical path cavity, comprising: the incident light is reflected for multiple times and then emitted from the incident hole, the annular lens group comprises one or two annular spherical lenses, the incident hole is formed in one of the annular spherical lenses of the annular lens group, and the reflecting surface of the annular spherical lens is positioned on the inner side wall of the annular spherical lens.
As one of the preferable schemes of the technical scheme, the multi-optical path cavity comprises an annular spherical mirror which is vertically symmetrical along the horizontal plane where the incident hole is positioned, the connecting line of the incident hole and the spherical center of the annular spherical mirror where the incident hole is positioned is an incident radius R, the included angle between the incident light and the incident radius is an incident angle theta, and when the light track of the incident light in the multi-optical path cavity is a positive P-star, the optical path length L of the incident light in the multi-optical path cavity is as follows 1 = (4k+3) ×2rcos θ, where p=4k+3, P is the number of sides of a regular polygonal star ray trace that an incident ray assumes in the multi-path cavity, θ=pi/(8k+6).
As one of the preferable schemes of the technical scheme, the multi-optical path cavity comprises two annular spherical mirrors which are overlapped and symmetrically arranged up and down, the incident hole is positioned on any one of the annular spherical mirrors, and after light is injected from the incident hole, light tracks with positive P-star top views are respectively formed in the two annular spherical mirrors and between the two annular spherical mirrors;
the connection line between the incident hole and the sphere center of the annular spherical mirror is an incident radius, the included angle between the incident light and the incident radius is an incident angle theta, and theta=pi/(8k+6), and the incident light is in multiple anglesOptical path cavity is of optical path length L 2 =3×4k+3×2rcos θ, p=4k+3, wherein k is a positive integer equal to or greater than 1.
As one of the preferable schemes of the technical scheme, the sphere centers of the two annular spherical mirrors are symmetrically distributed between two reflecting light spot layers formed in the two annular spherical mirrors by incident light rays.
As one of the preferable schemes of the technical scheme, the height of the annular spherical mirror is H, and the height H of the spherical center of the annular spherical mirror 2 =3h/4, height of the entrance aperture H 1 =h/2, and the distance c between the centers of the two annular spherical mirrors is H/2.
As one of the preferable schemes of the present invention, after the incident light rays enter the corresponding annular spherical mirror from the entrance hole, the midpoint of each reflection line in the multi-optical path cavity is the focal point of the annular spherical mirror, and the focal length of the annular spherical mirror is f=r×cos θ.
As one of the preferable schemes of the technical scheme, the interval between two reflection facula layers formed in the two annular spherical mirrors after the incident light rays are incident from the incident holes is Y, and Y/R is more than 0 and less than or equal to 1/60.
As one of the preferable schemes of the technical scheme, a focusing optical element for converging incident light is arranged in front of the incidence hole, the incident light is injected into the corresponding annular spherical mirror from the incidence hole through the focusing optical element, and the midpoint of the tangent line of the incident light in the annular spherical mirror is the focus of the focusing optical element.
As one of the preferable embodiments of the present invention, the focusing optical element is a focusing lens or a focusing mirror, and an optical axis of the focusing lens coincides with the incident light.
As one of the preferable schemes of the technical scheme, the inner radius of the annular spherical mirror is R, the outer radius is R ', and the beam radius of the incident light is R, so that the diameter a of the incident hole is larger than 2r+ (R' -R) sin theta.
The optical detection device comprises a multi-optical path cavity and a driving device connected with the multi-optical path cavity or the optical ranging device to be detected, wherein the driving device drives the multi-optical path cavity or the optical ranging device to be detected to rotate so as to change an incident angle, each set incident angle is used as a detection point position, and the detection point positions are correspondingly used for recording the measured distance of incident light rays sent by the optical ranging device to be detected after passing through the multi-optical path cavity and comparing the measured distance with the real distance of the incident light rays.
As one of the preferable schemes of the technical scheme, an attenuation sheet is arranged on an incident light path and/or a receiving light path of the optical ranging device to be measured.
As one of the preferable schemes of the technical scheme, the optical distance measuring device to be measured comprises an emission light source for emitting measuring light and a receiving detector for receiving emergent light emitted from the multi-optical path cavity, wherein the distance between the emission light source and the receiving detector is d, the incident light is perpendicular to the connecting line of the emission light source and the receiving detector, and the distance between the center of the focusing lens and the emission light source of the distance measuring device to be measured is s 1 The distance between the center of the focusing lens and the entrance hole is s 2 The distance from the incident hole to the detector of the emergent light is s 3 The s is 2 =f-Rcos θ, said s 1 =（Rcosθcos（2θ）+s 2 ）*m/（Rcosθsin（2θ）），s 3 =d/arctan(d/(s 1 +s 2 ) When the multi-path cavity comprises a circular spherical mirror, the true distance of the incident ray a=s 1 +s 2 +s 3 +L 1 。
As one of the preferable schemes of the technical scheme, the optical distance measuring device to be measured comprises an emission light source for emitting incident light and a receiving detector for receiving emergent light emitted from the multi-optical path cavity, wherein the incident light is perpendicular to the connecting line of the emission light source and the receiving detector, the distance between the emission light source and the receiving detector is d, and the distance between the emission light source of the distance measuring device to be measured and the reflecting point of the focusing reflector is s 1 The distance between the reflecting point of the focusing reflecting mirror and the incident hole is s 2 The distance from the incident hole to the detector of the emergent light is s 3 The s is 2 =f-Rcos θ, said s 1 =（Rcosθcos（2θ）+s 2 ）*m/（Rcosθsin（2θ）），s 3 =d/arctan(d/(s 1 +s 2 ) When the optical path cavity comprises two annular spherical mirrors, then the true distance of the incident ray a=s 1 +s 2 +s 3 +L 2 。
The detection method adopts the detection device to detect the optical ranging device to be detected, and comprises the following specific steps:
step one, adjusting the position of an optical ranging device to be measured or a multi-optical path cavity through a driving device, and setting incident angles with different angles as detection points;
step two, the optical distance measuring device to be measured emits incident light rays at each set detection point to measure distance, and outputs measured distance or measured light intensity corresponding to each detection point;
step three the measured distance and the real distance or the measured light intensity and the real distance of each detection point are compared, so as to judge whether the optical ranging device to be measured is qualified or not.
As one of the preferable embodiments of the present technical solution, the method further includes the step four: and correcting and compensating the optical ranging device to be measured according to the comparison result of the measured distance and the real distance of each detection point or the measured light intensity and the real distance.
The beneficial effects are that: through the matching of the annular lens group, the incidence hole and the incidence angle, the incident light rays are in a regular polygonal star shape in the multi-optical path cavity and are emitted along the original incidence hole, under the premise of reducing the occupied test field, the test environment that the optical ranging device to be tested sends out the emission light to the test target and receives the reflected emission light is simulated, and parameters such as the light and the temperature of the test are further controlled, so that the test data are more accurate and reliable.
Drawings
FIG. 1 is a top view of a multiple optical path cavity provided in embodiment 1 of the present invention;
FIG. 2 is a front view of a multiple optical path cavity provided in embodiment 1 of the present invention;
FIG. 3 is a block diagram of a multiple optical path cavity provided in embodiment 2 of the present invention;
fig. 4 is a top view of a toroidal spherical mirror with multiple optical path cavities according to embodiment 2 of the present invention:
fig. 5 is a front view of a toroidal spherical mirror with multiple optical path cavities according to embodiment 2 of the present invention:
FIG. 6 is a schematic diagram of a ray trace of an incident ray in a multi-path cavity according to embodiment 2 of the present invention;
fig. 7 is a block diagram of a focusing optical element detecting device according to embodiment 1 of the present invention;
fig. 8 is a block diagram of a focusing optical element detecting device using a focusing mirror according to embodiment 1 of the present invention;
fig. 9 is a block diagram of a focusing optical element detecting device according to embodiment 2 of the present invention;
fig. 10 is a block diagram of a focusing optical element detecting device according to embodiment 2 of the present invention.
1. An annular spherical mirror; 2. an entry hole; 4. an attenuation sheet; 11. an entry hole; 12. a center of sphere; 21. an emission light source; 22. a detector; 31. a focusing lens; 32. a focusing mirror.
Description of the embodiments
It should be noted that, in the case of no conflict, the embodiments and features in the embodiments may be combined with each other.
In order to make the present application solution better understood by those skilled in the art, the following description will be made in detail and with reference to the accompanying drawings in the embodiments of the present application, it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by one of ordinary skill in the art based on the embodiments herein without making any inventive effort, shall fall within the scope of the present application.
Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The technical scheme of the invention is further described below by the specific embodiments with reference to the accompanying drawings.
Examples
The present invention provides a multi-path cavity, as shown in fig. 1-2, comprising: the incident light is reflected for many times and then is emitted from the incident hole 11, the annular lens group comprises an annular spherical lens 1, the incident hole 11 is formed on the annular spherical lens 1, the annular spherical lens 1 is vertically symmetrical along the horizontal plane where the incident hole 11 is positioned, the reflecting surface of the annular spherical lens 1 is positioned on the inner side wall of the annular spherical lens 1, the connecting line of the incident hole 11 and the spherical center 12 of the annular spherical lens 1 where the incident hole is positioned is an incident radius R, the included angle between the incident light and the incident radius is an incident angle theta, the light track of the incident light in the multi-path cavity is in a normal P-star shape, and the light path length L of the incident light in the multi-path cavity is equal to the incident radius R 1 = (4k+3) ×2rcos θ, where p=4k+3, P is the number of sides of a regular polygonal star ray trace where an incident ray is in the multi-path cavity, θ=pi/(8k+6), where k is a positive integer greater than or equal to 1. Through the cooperation of annular sphere mirror 1 and incident hole 11 and incident angle for incident light is regular polygon star and follows former incident hole 11 and jet out at many optical path intracavity light orbit, under the prerequisite that reduces to occupy the test place, simulates the test environment that await measuring range unit sent the emission light to the test target and received the emission light after the reflection, further control test environment's illumination, parameters such as temperature, make test data more accurate reliable.
In order to ensure that the incident light is refocused and then reflected after each reflection after entering the annular spherical mirror 1, and ensure the light intensity of the reflected light, the focal length of the annular spherical mirror 1 is f=r×cos θ, so that the midpoint of each reflection line of the incident light in the multi-optical path cavity is the focal point of the annular spherical mirror 1, and the refocusing of each reflection of the incident light in the multi-optical path cavity is achieved, and the incident light is circularly reflected, focused and reflected in the annular spherical mirror 1 until the incident light is emitted from the incident hole 11.
In specific implementation, the value range of the incident angle θ can be determined according to the value range of the optical path set for the multi-optical path cavity, and the median value is taken according to the value range of the incident angle θ to determine that the focal length of the annular spherical mirror 1 is a value of f=r×cos θ; or the value of the annular spherical mirror 1 can be obtained by specifying one or more most common values or average values in the value range of the incident angle theta and bringing the values into a calculation formula of F=R×cos theta of the annular spherical mirror 1.
Taking the range of incidence angle theta as an example, the range of incidence angle theta is smaller than or equal to pi/14 and larger than 0, the range of cos theta is larger than or equal to 0.97437 and smaller than 1; that is, as the angle of θ becomes smaller, the value of cos θ approaches 1 infinitely, that is, the focal length of the annular spherical mirror 1 approaches R infinitely, and in order to obtain a longer optical path during testing, the smaller the value of θ is, the better the value is, so that in manufacturing, the focal length of the annular spherical mirror 1 is set to R, so that the midpoint of each reflection line of an incident ray in the annular spherical mirror 1 approaches the focal point of the annular spherical mirror 1 infinitely.
In order to converge the incident light rays each time, the incident light rays are prevented from being diverged after being reflected in the annular spherical mirror 1 for a plurality of times, a focusing optical element for converging the incident light rays and changing the angle of the emergent light rays is arranged in front of the incident hole 11, the incident light rays are emitted into the corresponding annular spherical mirror 1 from the incident hole 11 through the focusing optical element, and the midpoint of a tangent line of the incident light rays in the annular spherical mirror 1 is the focal point of the focusing optical element. The focusing optical element is a focusing lens 31 or a focusing mirror 32, and the optical axis of the focusing lens 31 coincides with the incident light.
The annular spherical mirror 1 has a certain thickness, in order to ensure that incident light smoothly enters the annular spherical mirror 1 from the incident hole 11, the inner radius of the annular spherical mirror 1 is R, the outer radius of the annular spherical mirror 1 is R ', the beam radius of the incident light is R, then the diameter a of the incident hole 11 is greater than 2r+ (R' -R) ×sin θ, and the aperture of the incident hole 11 is determined according to the range of incident angles and the sizes of the inner radius and the outer radius of the annular spherical mirror 1, so that the incident light in the set or theoretical incident angle range can enter the multi-optical path cavity, and the accuracy of test data is ensured.
The invention also provides an optical detection device, as shown in fig. 7-8, comprising the multi-optical path cavity and a driving device connected with the multi-optical path cavity or the optical distance measuring device 2 to be detected, wherein the driving device drives the multi-optical path cavity or the optical distance measuring device 2 to be detected to rotate so as to change an incident angle, the optical distance measuring device 2 to be detected takes each set incident angle as a detection point position, and the detection distance of the incident light emitted by the optical distance measuring device 2 to be detected after passing through the multi-optical path cavity is recorded corresponding to each detection point position and is compared with the real distance of the incident light.
In order to ensure the stability of the multi-optical path cavity and prevent the small error caused by the rotation of the driving device from affecting the optical path of the incident light, the driving device is connected to the optical ranging device 2 to be measured, the driving device adjusts the value of the incident angle theta according to the set detection points, the optical ranging device 2 to be measured measures each detection point and outputs the measured distance or the measured light intensity of each detection point, and the measured distance or the measured light intensity of each detection point is compared with the real distance corresponding to each detection point to determine the measurement accuracy of the optical ranging device 2 to be measured and judge whether the measured accuracy or not is qualified.
In order to further simulate the scene of light intensity attenuation of incident light caused by weather, environment and other factors in the actual measurement environment, the incident light is attenuated by the attenuation sheet 4 on the incident light path and the receiving light path. The attenuation sheet 4 is arranged between the optical distance measuring device 2 to be measured and the focusing optical element. Preferably, the attenuation amount of the attenuation sheet 4 is adjustable.
The optical distance measuring device 2 to be measured comprises an emitting light source 21 for emitting incident light and a receiving detector 22 for receiving the emergent light emitted from the multi-path cavity, wherein the distance between the emitting light source 21 and the receiving detector 22 is d, and the incident light is perpendicular to the connection line between the emitting light source 21 and the receiving detector 22, and when the focusing optical element is a focusing lens 31, as shown in fig. 7, the center of the focusing lens 31 is spaced from the emitting light source 21 of the optical distance measuring device 2 to be measuredSeparation of is s 1 The distance between the center of the focusing lens 31 and the incident hole 11 is s 2 The distance from the incident hole 11 to the detector 22 is s 3 The focal length of the focusing lens 31 is f; the s is 2 =f-Rcos θ, said s 1 =（Rcosθcos（2θ）+s 2 ）*m/（Rcosθsin（2θ）），s 3 =d/arctan(d/(s 1 +s 2 ) True distance a=s) of incident light 1 +s 2 +s 3 +L 1 。
As shown in fig. 8, when the focusing optical element is the focusing mirror 32, the distance between the emission light source 21 of the optical ranging device 2 to be measured and the reflection point of the focusing mirror 32 is s 1 The distance between the reflecting point of the focusing mirror 32 and the incident hole 11 is s 2 The distance from the incident hole 11 to the detector 22 is s 3 The focal length of the focusing mirror 32 is f; the s is 2 =f-Rcos θ, said s 1 =（Rcosθcos（2θ）+s 2 ）*d/（Rcosθsin（2θ）），s 3 =d/arctan(d/(s 1 +s 2 ) True distance a=s) of incident light 1 +s 2 +s 3 +L 1 。
The invention also provides a detection method, which adopts the detection device to detect the optical ranging device 2 to be detected, and comprises the following specific steps:
step one, adjusting the position of an optical ranging device 2 to be measured by a driving device, and taking the set incident angles with different angles as detection points;
step two, the optical distance measuring device 2 to be measured sends out incident light rays at each set detection point location to measure distance, and outputs the measured distance or measured light intensity of each detection point location;
and thirdly, comparing the measured distance and the real distance or the measured light intensity and the real distance of each detection point to judge whether the optical ranging device 2 to be detected is qualified or not.
And step four, correcting and compensating the optical ranging device 2 to be measured according to the comparison result of the measured distance and the real distance or the measured light intensity and the real distance of each detection point.
Examples
Unlike embodiment 1, as shown in fig. 3, the annular lens group includes two annular spherical lenses 1 disposed symmetrically in an up-down overlapping manner, the incident hole 11 is located on any one of the annular spherical lenses 1, incident light is reflected between the two annular spherical lenses 1 and the two annular spherical lenses 1 after entering from the incident hole 11 to form a light track with a top view of a normal P-star shape, the connection line between the incident hole 11 and the spherical center 12 of the annular spherical lens 1 is an incident radius R, the angle between the incident light and the incident radius is an incident angle θ, and the optical path length L of the incident light in the multi-optical path cavity 2 =3×4k+3×2rcos θ. Wherein, p=4k+3, P is the number of sides of a regular polygon star when the incident light ray trace in the multi-path cavity is seen from the top, K is a positive integer greater than or equal to 1, and θ=pi/(8k+6). Compared with the structure of one annular spherical mirror 1 in the embodiment 1, the structure of two annular spherical mirrors 1 further increases the reflection times of the incident light rays between the annular spherical mirrors 1, and the optical path of the incident light rays in the multi-path cavity is improved in multiple.
A schematic diagram of a top view of a ray trace of incident light in the multi-path cavity is a positive 15-pointed star, as shown in FIG. 6, the reflection number in the lower annular spherical mirror 1 is A n The number of the reflection point in the upper annular spherical mirror 1 is B n Taking the incident hole 11 arranged on the lower annular spherical mirror 1 as an example, after the incident light enters from the incident hole 11, 15 reflection points are respectively A on the lower annular spherical mirror 1 1 -A 15 . At A 1 45 th reflection at point A 2 Point 17 and 32 reflections occur at A 3 Point 4 th reflection at A 4 The 21 st and 36 th reflections at point A 5 Point 8 th reflection at A 6 The 25 th reflection and 40 th reflection occur at point A 7 Point 12 th reflection at A 8 The 29 th and 44 th reflections at point A 9 Point 1 st and 16 th reflections, at A 10 Point 33 th reflection at A 11 Point occurrence of 5 th reflection and 20 th reflectionShooting, at A 12 Point 37 th reflection, at A 13 The 9 th reflection and 24 th reflection occur at point A 14 Point 41 st reflection at A 15 The 13 th reflection and the 28 th reflection of the dot occur.
The incident light has 15 reflection points on the upper annular spherical mirror 1, respectively B 1 -B 15 . At B 1 Point 15 th and 30 th reflections, at B 2 Point 2 nd reflection at B 3 Point 19 th and 34 th reflections occur at B 4 Point 6 th reflection at B 5 Point 23 and 38 reflections occur at point B 6 Point 10 th reflection at B 7 Point 27 th and 42 th reflections occur at B 8 Point 14 th reflection at B 9 Point 31 st reflection at B 10 Point 3 rd and 18 th reflections occur at B 11 Point 35 th reflection at B 12 Point 7 th and 22 th reflections occur at B 13 Point 39 th reflection, at B 14 Point 11 th and 26 th reflections occur at B 15 The 43 rd reflection of the spot occurs.
In order to ensure that the incident light is reflected between the two annular spherical mirrors 1, the centers 12 of the two annular spherical mirrors 1 are symmetrically distributed between two reflective spot layers formed by the incident light in the two annular spherical mirrors 1.
In order to ensure that the incident light is reflected again after being refocused after each reflection of the incident light is incident into the annular spherical mirror 1, and ensure the light intensity of the reflected light, when the structure of the annular spherical mirror 1 meets the requirements, the focal length f=r×cos θ of the annular spherical mirror 1, when the number of sides of the regular polygon star is larger, the smaller the angle of the incident angle θ is, and the r×cos θ is more approximate to R, each reflection of the incident light in the annular spherical mirror 1 is infinitely close to the spherical center 12 of the annular spherical mirror 1, so that the condensation of the light in the annular spherical mirror 1 is ensured, the incident light is reflected in the annular spherical mirror 1 according to the set optical path, no scattering and no diffusion are caused, and the probability of stray light noise in the test is reduced.
In specific implementation, the value range of the incident angle θ can be determined according to the value range of the optical path set for the multi-optical path cavity, and the median value is taken according to the value range of the incident angle θ to determine that the focal length of the annular spherical mirror 1 is a value of f=r×cos θ; or the value of the annular spherical mirror 1 can be obtained by specifying one or more most common values or average values in the value range of the incident angle theta and bringing the values into a calculation formula of F=R×cos theta of the annular spherical mirror 1.
Taking the range of incidence angle theta as an example, the range of incidence angle theta is smaller than or equal to pi/14 and larger than 0, the range of cos theta is larger than or equal to 0.97437 and smaller than 1; that is, as the angle of θ becomes smaller, the value of cos θ approaches 1 infinitely, that is, the focal length of the annular spherical mirror 1 approaches R infinitely, and in order to obtain a longer optical path during testing, the smaller the value of θ is, the better the value is, so that in manufacturing, the focal length of the annular spherical mirror 1 is set to R, so that the midpoint of each reflection line of an incident ray in the annular spherical mirror 1 approaches the focal point of the annular spherical mirror 1 infinitely.
Preferably, as shown in fig. 4-5, the height of the annular spherical mirror 1 is H, taking the annular spherical mirror 1 arranged at the lower layer as an example, and the height of the spherical center 12 of the annular spherical mirror 1 is H 2 The H is 2 Equal to 3H/4, that is, the sphere center 12 is positioned at the H/4 position of the height of the annular spherical mirror 1, and the distance c between the sphere centers 12 of the two annular spherical mirrors 1 is H/2. The height of the inlet hole 11 is H 1 The H is 1 Equal to H/2, i.e. the entrance aperture 11 is located at 1/2 of the annular spherical mirror 1. The sphere center 12 is positioned at the H/4 position of the height of the annular spherical mirror 1, the inlet hole 11 is positioned at the H/2 position of the annular spherical mirror 1, and the height difference between the sphere center 12 and the inlet hole 11 ensures that the incident light can still be tightly attached to the sphere center 12 for multiple reflections between the two annular spherical mirrors 1 according to a set path when the value of the angle theta is maximum.
The interval between the two reflection spot layers formed in the two annular spherical mirrors 1 after the incident light is incident from the incident hole 11 is Y, and in theory, when Y < R >, the setting is fully satisfied that the focus point of the reflection of the incident light within the annular spherical mirror 1 is approximately equal to the focus of the annular spherical mirror 1. In a specific test process, when Y is more than 0 and less than or equal to 1/60, and when Y meets the conditions, the focusing point of reflection of incident light rays in the annular spherical mirror 1 is close to the focus of the annular spherical mirror 1, it is ensured that every reflection of the incident light ray in the annular spherical mirror 1 is focused close to the centre of sphere 12.
In order to ensure the collimation of the incident light and ensure the convergence of the incident light at the incident hole 11, a focusing optical element for converging the incident light and changing the angle of the emergent light is arranged in front of the incident hole 11, the incident light is injected into the corresponding annular spherical mirror from the incident hole 11 through the focusing optical element, and the midpoint of the tangent line of the incident light in the annular spherical mirror is the focus of the focusing optical element.
Preferably, the focusing optical element is a focusing lens 31 or a focusing mirror 32, the optical axis of the focusing lens 31 coincides with the incident light.
Since the annular spherical mirror 1 has a certain thickness, in order to ensure that the incident light is smoothly injected into the annular spherical mirror 1 from the incident hole 11, the inner radius of the annular spherical mirror 1 is R, the outer radius of the annular spherical mirror 1 is R ', and the beam radius of the incident light is R, the diameter a of the incident hole 11 is greater than 2r+ (R' -R) ×sin θ.
The invention also provides an optical detection device, as shown in fig. 9-10, comprising the multi-optical path cavity and a driving device connected with the multi-optical path cavity or the optical distance measuring device 2 to be detected, wherein the driving device drives the multi-optical path cavity or the optical distance measuring device 2 to be detected to rotate so as to change an incident angle, the optical distance measuring device 2 to be detected takes each set incident angle as a detection point position, and the detection distance of the incident light emitted by the optical distance measuring device 2 to be detected after passing through the multi-optical path cavity is recorded corresponding to each detection point position and is compared with the real distance of the incident light.
In order to ensure the stability of the multi-optical path cavity and prevent the small error caused by the rotation of the driving device from affecting the optical path of the incident light, the driving device is connected to the optical ranging device 2 to be measured, the driving device adjusts the value of the incident angle theta according to the set detection points, the optical ranging device 2 to be measured measures each detection point and outputs the measured distance or the measured light intensity of each detection point, and the measured distance or the measured light intensity of each detection point is compared with the real distance corresponding to each detection point to determine the measurement accuracy of the optical ranging device 2 to be measured and judge whether the measured accuracy or not is qualified.
In order to further simulate the scene of light intensity attenuation of incident light caused by weather, environment and other factors in the actual measurement environment, the incident light is attenuated by the attenuation sheet 4 on the incident light path and the receiving light path. The attenuation sheet 4 is arranged between the optical distance measuring device 2 to be measured and the focusing optical element. Preferably, the method comprises the steps of, the attenuation amount of the attenuation sheet 4 is adjustable.
The optical distance measuring device 2 to be measured comprises an emitting light source 21 for emitting incident light and a receiving detector 22 for receiving emergent light emitted from the multi-path cavity, wherein the distance between the emitting light source 21 and the receiving detector 22 is d, and when the focusing optical element is a focusing lens 31, as shown in fig. 9, the distance between the center of the focusing lens 31 and the emitting light source 21 of the optical distance measuring device 2 to be measured is s 1 The center of the focusing lens 31 a distance s from the incident hole 11 2 The distance from the incident hole 11 to the detector 22 is s 3 The focal length of the focusing lens 31 is f; the s is 2 =f-Rcos θ, said s 1 =（Rcosθcos（2θ）+s 2 ）*m/（Rcosθsin（2θ）），s 3 =d/arctan(d/(s 1 +s 2 ) True distance a=s) of incident light 1 +s 2 +s 3 +L 2 。
When the focusing optical element is the focusing mirror 32, as shown in fig. 10, the distance between the emission light source 21 of the distance measuring device and the reflection point of the focusing mirror 32 is s 1 The distance between the reflecting point of the focusing mirror 32 and the incident hole 11 is s 2 The distance from the incident hole 11 to the detector 22 is s 3 The focal length of the focusing mirror 32 is f; the s is 2 =f-Rcos θ, said s 1 =（Rcosθcos（2θ）+s 2 ）*d/（Rcosθsin（2θ）），s 3 =d/arctan(d/(s 1 +s 2 ) True distance a=s) of incident light 1 +s 2 +s 3 +L 2 。
The invention also provides a detection method, which adopts the detection device to detect the optical ranging device 2 to be detected, and comprises the following specific steps:
step one, adjusting the position of an optical ranging device 2 to be measured by a driving device, and taking the set incident angles with different angles as detection points;
step two, the optical distance measuring device 2 to be measured sends out incident light rays at each set detection point location to measure distance, and outputs the measured distance or measured light intensity of each detection point location;
and thirdly, comparing the measured distance and the real distance or the measured light intensity and the real distance of each detection point to judge whether the optical ranging device 2 to be detected is qualified or not.
And step four, correcting and compensating the optical ranging device 2 to be measured according to the comparison result of the measured distance and the real distance or the measured light intensity and the real distance of each detection point.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, one skilled in the art may make modifications and equivalents to the specific embodiments of the present invention, and any modifications and equivalents not departing from the spirit and scope of the present invention are within the scope of the claims of the present invention.
Claims (13)
1. A multiple optical path cavity, comprising: the annular lens group is used for emitting incident light rays from an incident hole after multiple reflections, the annular lens group comprises one or two annular spherical lenses, the incident hole is formed in one of the annular spherical lenses of the annular lens group, and the reflecting surface of the annular spherical lens is positioned on the inner side wall of the annular spherical lens;
the multi-optical path cavity comprises an annular spherical mirror, the annular spherical mirror is vertically symmetrical along the horizontal plane where an incident hole is located, the connection line between the incident hole and the spherical center of the annular spherical mirror is an incident radius R, then the included angle between an incident ray and the incident radius is an incident angle theta, the ray track of the incident ray in the multi-optical path cavity is a positive P-star, the optical path length L1= (4k+3) 2Rcos theta of the incident ray in the multi-optical path cavity, wherein P=4k+3, P is the number of sides of the positive multi-star ray track of the incident ray in the multi-optical path cavity, and theta=pi/(8k+6), wherein k is a positive integer greater than or equal to 1;
or the multi-optical path cavity comprises two annular spherical mirrors which are vertically overlapped and symmetrically arranged, the incident hole is positioned on any one of the annular spherical mirrors, incident light rays are reflected in the two annular spherical mirrors and between the two annular spherical mirrors after entering from the incident hole to form a light ray track with a top view of a positive P-star shape, the connecting line of the incident hole and the spherical center of the annular spherical mirror where the incident hole is positioned is an incident radius, then the included angle between the incident light rays and the incident radius is an incident angle theta, and theta=pi/(8k+6), and the optical path length L2 = 3 (4k+3) of the incident light rays in the multi-optical path cavity is 2Rcos theta, and P=4k+3, wherein k is a positive integer greater than or equal to 1.
2. The multiple optical path cavity of claim 1, wherein the centers of the two annular spherical mirrors are symmetrically disposed between two reflective spot layers formed by incident light rays within the two annular spherical mirrors.
3. The multiple optical path cavity according to claim 2, wherein the height of the annular spherical mirrors is H, the height of the centers of spheres of the annular spherical mirrors h2=3h/4, the height of the entrance aperture h1=h/2, and the distance of the centers of spheres of the two annular spherical mirrors c=h/2.
4. A multipass cavity according to any of claims 1 to 3, wherein the midpoint of each reflection line in the multipass cavity after an incident ray enters the corresponding annular spherical mirror from the entrance aperture is the focal point of the annular spherical mirror, and the focal length of the annular spherical mirror is F = R x cos θ.
5. A multipass cavity according to any of claims 1 to 3, wherein the spacing between two reflective spot layers formed in two of said annular spherical mirrors after incidence of incident light from the incidence aperture is Y,0 < Y/r.ltoreq.1/60.
6. A multi-path cavity according to any one of claims 1 to 3, wherein a focusing optical element for converging incident light is provided in front of the entrance aperture, the incident light is incident from the entrance aperture through the focusing optical element into a corresponding annular spherical mirror, and a midpoint of a tangent of the incident light within the annular spherical mirror is a focal point of the focusing optical element.
7. The multiple optical path cavity according to claim 6, wherein the focusing optical element is a focusing lens or a focusing mirror, and an optical axis of the focusing lens coincides with the incident light.
8. A multipass cavity according to any of claims 1 to 3, wherein the annular spherical mirror has an inner radius R, the annular spherical mirror has an outer radius R ', and the incident light beam has a beam radius R, and the diameter of the entrance aperture a > 2r+ (R' -R) sin θ.
9. An optical detection device, comprising a multi-optical path cavity as claimed in any one of claims 1 to 8, and a driving device connected to the multi-optical path cavity or the optical distance measuring device to be detected, wherein the driving device drives the multi-optical path cavity or the optical distance measuring device to be detected to rotate so as to change the incident angle of incident light, and the optical distance measuring device to be detected uses each set incident angle as a detection point, and records the measured distance of the incident light emitted by the optical distance measuring device to be detected after passing through the multi-optical path cavity corresponding to each detection point and compares the measured distance with the real distance of the incident light.
10. The optical detection device according to claim 9, wherein an attenuation sheet is arranged on an incident light path and/or a receiving light path of the optical ranging device to be measured.
11. The optical detection device according to claim 9 or 10, wherein the optical ranging device to be detected comprises an emission light source for emitting incident light and a receiving detector for receiving outgoing light from the multi-path cavity, the incident light is perpendicular to a connection line between the emission light source and the receiving detector, a focusing optical element for converging the incident light is arranged in front of the entrance hole, the incident light enters a corresponding annular spherical mirror from the entrance hole through the focusing optical element, a midpoint of a tangent line of the incident light in the annular spherical mirror is a focal point of the focusing optical element, the focusing optical element is a focusing lens or a focusing mirror, an optical axis of the focusing lens coincides with the incident light, a distance between the emission light source and the receiving detector is d, a focal length of the focusing lens or the focusing mirror is f, a distance between a center of the focusing lens or a reflection point of the focusing mirror and the emission light source of the ranging device to be detected is s1, a distance between a center of the focusing lens or a reflection point of the focusing mirror and the entrance is s2, a distance between the outgoing light from the entrance hole and the detector is 3 s = s-2 s/(s-s = 2 s +s (s = 2 s +2 s/(s 2 s = s + s2 s);
when the multi-path cavity comprises a circular spherical mirror, the true distance a=s1+s2+s3+l1 of the incident ray; when the optical path cavity comprises two annular spherical mirrors, the true distance a=s1+s2+s3+l2 of the incident light ray.
12. A detection method, characterized in that an optical detection device according to any one of claims 9-11 is used for detecting an optical distance measuring device to be detected, comprising the following steps:
step one, adjusting the position of an optical ranging device to be measured or a multi-optical path cavity through a driving device, and taking the set incident angles with different angles as detection points;
step two, the optical distance measuring device to be measured emits incident light rays at each set detection point to measure distance, and outputs measured distance or measured light intensity corresponding to each detection point;
and thirdly, comparing the measured distance and the real distance or the measured light intensity and the real distance of each detection point to judge whether the optical ranging device to be detected is qualified or not.
13. The method of detecting according to claim 12, further comprising the steps of:
and step four, correcting and compensating the optical ranging device to be measured according to the comparison result of the measured distance and the real distance or the measured light intensity and the real distance of each detection point.
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| CN112540360B (en) * | 2019-09-23 | 2023-10-13 | 北醒（北京）光子科技有限公司 | Radar and angle adjusting device |
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