CN216083083U - Coaxial optical system for laser ranging - Google Patents
Coaxial optical system for laser ranging Download PDFInfo
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- CN216083083U CN216083083U CN202122146546.6U CN202122146546U CN216083083U CN 216083083 U CN216083083 U CN 216083083U CN 202122146546 U CN202122146546 U CN 202122146546U CN 216083083 U CN216083083 U CN 216083083U
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Abstract
The utility model relates to a coaxial optical system for laser ranging, which comprises a conical optical machine chamber, wherein a collecting lens is arranged at the upper part of the optical machine chamber, a central hole is formed in the center of the collecting lens, a collimating lens is arranged in the central hole of the collecting lens, the optical axis of the collecting lens is coaxial with the optical axis of the collimating lens, a collecting lens pressing ring for axially fixing the collecting lens is sleeved on the side surface of the collecting lens, extinction grains are arranged inside the optical machine chamber, a light return receiver is arranged at the lower part of the optical machine chamber, and an adjusting gasket is arranged at the lower part of the light return receiver. The utility model reduces the volume of the optical module, reduces the cost and reduces the workload of adjusting the position of the device.
Description
Technical Field
The present invention relates to coaxial optical systems, and more particularly to a coaxial optical system for laser ranging.
Background
The basic principle of pulsed laser ranging, also known as TOF ranging, is to measure the time of flight of a laser pulse from transmission to reception and thus the precise distance between the laser emitting device and the target location. As shown in fig. 1, the transmitter transmits a beam of working light pulses to the target object, and also provides a beam of reference light pulses to the system; after the receiver receives the backscattering echo pulse of the target object, the time difference t between the reference light pulse and the echo pulse is obtained through a system timerLThe distance S to the target point can be calculated as follows.
In the above formula, C is the speed of light.
The optical system for pulse ranging includes an emission optical system and a reception optical system. The laser beam emitted by the laser is not absolutely parallel, and generally has a divergence angle of a few milliradians, if the laser beam is directly emitted to the space without any optical system, the diameter of a light spot of the laser beam is very large when the laser beam reaches a distant target, and the shape of the light spot does not meet the requirement of a laser radar. The transmitting optical system is generally a group of lens systems, and the beam width and the sectional area of the laser beam are changed by compressing the divergence angle of the laser beam, so that the purpose of increasing the light radiation density is achieved, and the capability of the laser radar for illuminating a target is improved.
The receiving optical system has the function of converging laser energy reflected by a target to a detector as much as possible, and simultaneously properly limiting a receiving field of view and reducing the influence of stray light, thereby improving the signal-to-noise ratio of the receiving system.
An optical portion of a pulse laser ranging system in the prior art mainly comprises a pulse laser, a collimating mirror, a return light reflecting mirror, a condensing mirror, a reference light receiver, a return light receiver and a main body structure, as shown in fig. 2. The pulse laser outputs two optical fibers of working light and reference light, and the energy of the working light is generally far greater than that of the reference light. The reference optical fiber is directly interfaced to the reference optical receiver for providing initial time information. The working light fiber is connected to the collimating lens in an abutting mode, the collimating lens expands emergent light of the pulse laser and compresses a beam divergence angle of the pulse laser. The pulse laser, the working optical fiber and the collimating mirror form a transmitting system; the return reflector, the condenser and the return receiver form a receiving system.
The collimated working light is emitted to a target object, diffuse reflection is generated on the surface of the target object, part of the backscattered energy returns along the original path and reaches a condenser after being reflected by a return light reflector, the condenser focuses the backscattered energy and condenses and compresses the energy to a small area, and a return light receiver can recognize the return light. The reference light and the return light are subjected to photoelectric conversion by the reference light receiver and the return light receiver to obtain electric signals of the outgoing light and the return light. The round-trip flight time of the laser can be obtained by measuring the time difference of the two electric signals, so that the distance to be measured is calculated.
SUMMERY OF THE UTILITY MODEL
The utility model aims to provide a coaxial optical system for laser ranging, which reduces the volume of an optical module, reduces the cost and reduces the workload of device position adjustment.
The technical scheme adopted by the utility model for solving the technical problems is as follows: the utility model provides a structure a coaxial optical system for laser rangefinder, includes conical ray apparatus room, ray apparatus room upper portion is provided with the condensing lens, the centre bore has been seted up at the center of condensing lens, be provided with the collimating mirror in the centre bore of condensing lens, the condensing lens optical axis with the collimating mirror optical axis is coaxial, condensing lens side cover is equipped with and is used for the condensing lens clamping ring to the condensing lens axial fixity, the inside of ray apparatus room is provided with extinction line, ray apparatus room lower part is provided with back light receiver, back light receiver lower part is provided with adjusting shim.
In the above scheme, the convex surface of the condenser lens is provided with a band-pass filter, and the band-pass filter is sleeved outside the collimating lens.
In the scheme, the plane end of the condenser lens is plated with a band-pass filter film.
In the above scheme, the collimating lens is fixedly arranged on the central hole of the collecting lens, the outer diameter of the collimating lens barrel is matched and matched with the diameter of the central hole of the collecting lens, and the collimating lens barrel is provided with a flange.
In the scheme, the convex end and the planar end of the condenser lens are plated with antireflection films.
In the above scheme, a return light receiver motherboard is arranged at the lower part of the return light receiver.
In the above scheme, the center of the band-pass filter is provided with a center hole, and the diameter size of the center hole of the band-pass filter is matched with the outer diameter of the collimating lens barrel.
In the above scheme, the light-sensitive surface of the return light receiver is arranged at the focus of the condenser lens.
In the scheme, the surface of the extinction pattern is coated with an adsorption coating of a working light wave band.
The coaxial optical system for laser ranging has the following beneficial effects:
1. according to the utility model, a return light reflector is omitted, so that an optical path L of return light is deformed into an I shape with coaxial light receiving and emitting, and the optical path of the return light is coaxial with an optical path of the emergent light, so that the imaging quality of the system for receiving light is optimized, the volume of an optical module is reduced, and the light weight is realized;
2. the center of the condenser is provided with the hole, the collimating lens is directly integrated in the center hole of the condenser, so that the optical axes of emergent light and returning light are coaxial, and on the basis, the position of the light-sensitive surface of the returning light receiver is adjusted to the focus of the condenser in the process of assembling and adjusting the optical device, so that the assembling and adjusting workload and the assembling and adjusting difficulty of the optical device of the system are greatly simplified;
3. the utility model abandons the return light reflector, avoids the reflection loss of the return light on the return light reflector and improves the distance measuring capability;
4. the front end of the condenser lens is provided with the band-pass filter, so that ambient light except the working light wavelength is cut off, and the ambient light is prevented from entering a photosensitive surface of the return light receiver, so that the optical background noise and the false alarm rate are lower;
5. the utility model adds the extinction lines in the optical machine room structure, and coats the absorption coating of the working light wave band on the surface of the extinction lines, which can effectively reduce the stray light of the working light wave band in the environment light from entering the return light receiver, thereby reducing the optical bottom noise and the false alarm rate.
Drawings
The utility model will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a pulsed laser ranging method;
FIG. 2 is a schematic diagram of a prior art pulsed laser ranging system;
FIG. 3 is a schematic diagram of the coaxial optical system for laser ranging according to the present invention;
FIG. 4 is a schematic view of a coaxial structure of a condenser and a collimator;
FIG. 5 is a schematic view of an extinction mark;
FIG. 6 is a half-sectional isometric view of the coaxial optical system for laser ranging of the present invention.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
As shown in fig. 3 to 6, the coaxial optical system for laser ranging of the present invention includes an optical machine room 5, a condenser 4 is disposed on an upper portion of the optical machine room 5, the condenser 4 is a receiving antenna for returning light, a center hole is opened in a center of the condenser 4, a collimator lens 1 is disposed in the center hole of the condenser 4, and the collimator lens 1 is a transmitting antenna for emitting light. The optical axis of the collimating lens 1 and the optical axis of the collecting lens 4 are coaxially arranged, the coaxial arrangement can simplify the light path, the structure is compact, and the quality of light spots received by the collecting lens 4 is good.
The middle part of ray machine room 5 is provided with conical extinction line 9, be provided with unevenness's line on extinction line 9's the inner wall, ray machine room 5 lower part is provided with back light receiver 6, the lower part of returning light receiver 6 is provided with back light receiver mother board 7, it sets up with 4 optical axes of condensing lens coaxial to return light receiver 6, it is located 4 focuses on the condensing lens to return light receiver 6's detection photosurface, it is used for receiving the light signal of return light and turning into the signal of telecommunication to return light receiver 6, because there is the error in the focus of condensing lens 4 and the encapsulation height of returning light receiver 6, be provided with adjusting shim 8 between returning light receiver mother board 7 and ray machine room 5, be used for correcting this error, adjusting shim 8 is with returning light receiver mother board 7 bed hedgehopping, make the focus of condensing lens 4 accurately fall on the photosurface of returning light receiver 6. The side cover of condenser 4 is equipped with and is used for 4 axial fixity's condenser clamping ring 3 to the condenser, and 4 convex surfaces of condenser are provided with band pass filter 2, and band pass filter 2 is arranged in cutting off the ambient light of non-work light wave band in the return light, avoids it to get into the sensitization face of returning light receiver 6, improves the SNR of system, and the outside at collimating mirror 1 is established to band pass filter 2 cover. Or the band-pass filter 2 is not arranged, and the band-pass filter film is directly plated at the plane end of the condenser 4, so that the same effect can be achieved. The center of the condenser 4 is provided with a central hole of the condenser 4, and the axis of the central hole of the condenser 4 is coaxial with the optical axis of the condenser 4. All optical devices in the system are directly or indirectly fixed on the optical machine chamber 5, the optical machine chamber 5 is of an integrated closed structure, and the rigidity of the optical machine chamber can ensure the stability of the adjusting position of each optical device.
The collimating lens 1 is fixedly arranged on a central hole in the center of the collecting lens 4, the outer diameter of the lens barrel of the collimating lens 1 is matched and matched with the diameter of the central hole of the collecting lens 4 and used for radial positioning of the collimating lens 1, and a flange flanging is arranged on the lens barrel of the collimating lens 1 and used for axial positioning of the collimating lens 1. The convex end and the plane end of the condenser lens 4 are plated with antireflection films for improving the working light wave band of the working light transmittance. The center of the band-pass filter 2 is provided with a center hole, the diameter size of the center hole is matched with the outer diameter of the lens barrel of the collimating mirror 1, and the collimating mirror 1 can penetrate out of the center hole. The light-sensitive surface of the return light receiver 6 is arranged at the focus of the condenser lens 4.
There are 2 optical axes in a typical laser ranging optical system, namely the optical axis of the transmitting antenna and the optical axis of the receiving antenna. When the two optical axes are not coaxial, the imaging quality of the received light may be degraded, and the distance measurement capability may be even impaired. The utility model directly integrates the transmitting antenna and the receiving antenna, and has coaxial layout, thereby not only enabling the receiving antenna to achieve the best imaging quality, but also reducing the occupied volume of optical devices and optical paths in the system to the greatest extent, and realizing miniaturization and light weight. According to the coaxial implementation method of the optical axis, a central hole is formed in the central area of the condenser lens 4, the axis of the central hole is coaxial with the optical axis of the condenser lens 4, and the diameter of the central hole is matched with the outer diameter of the lens barrel of the collimating lens 1 and used for radial positioning; a flange is reserved on the lens barrel of the collimating lens 1 and used for axially positioning the collimating lens 1. After the collimating lens 1 is inserted into the central hole of the collecting lens 4, only the freedom degree of the rotation direction exists, and the freedom degree does not influence the coaxiality of the optical axis.
The detection wavelength range of the return light receiver 6 is usually between several hundreds to thousands of nanometers, and the operating light wavelength of the system is a single wavelength, so that ambient light energy in a non-operating band outside the system enters the return light receiver 6 to cause a response, thereby generating a noise floor and even a false alarm. In the utility model, the convex end of the condenser lens 4 is provided with the band-pass filter 2, and the central wavelength of the band-pass filter 2 is the wavelength of the system working light. The center of the band-pass filter 2 is provided with a center hole, the diameter size of the center hole is matched with the outer diameter of the lens barrel of the collimating mirror 1, the collimating mirror 1 penetrates through the center hole of the band-pass filter 2, the working light energy can only pass through the band-pass filter 2 when returning, and the emergent energy cannot be weakened. The band-pass filter 2 is used for cutting off the ambient light of the non-working light wave band in the return light, reducing the optical background noise and the false alarm, and can effectively reduce the optical background noise and the false alarm rate. Emergent light can directly leave the system from the collimating mirror 1, energy loss caused by light passing through the light filter is avoided, external return light can enter the system only by passing through the light filter, and accordingly ambient light outside a working waveband is prevented from entering the system.
In order to ensure that the received light of the system achieves the optimal imaging quality, two points are required to be achieved: firstly, in design, the diameter of a convergent focal spot of the condenser 4 must be smaller than the diameter of a photosensitive surface of the return light receiver 6; second, when the return light receiver 6 is installed, its light-sensing surface must be accurately placed at the focal point of the condenser lens 4. On the other hand, errors exist in the focal length of the condenser lens 4 and the packaging height of the return light receiver 6, and the errors cause the return light receiver motherboard 7 to be required to be adjusted in the depth of focus direction of the condenser lens 4 when being installed in the optical machine chamber 5. The axial dimension of the optical machine room 5 (i.e. the dimension from the plane end of the condenser lens 4 to the installation surface of the return light receiver motherboard 7) is set to negative tolerance, and an adjusting gasket 8 is added between the optical machine room 5 and the return light receiver motherboard 7. The thickness of the adjusting shim 8 is determined by measuring the distance from the focal point of the condenser lens 4 to the mounting surface of the return light receiver motherboard 7.
In the utility model, the optical machine room 5 is designed integrally, so that enough rigidity is ensured, and the mutual position relation between the precisely-adjusted optical devices is reliably ensured. The openings at the two ends of the optical machine room 5 are closed by the band-pass filter 2 and the light return receiver mother board 7, and the whole ranging system forms a closed structure. The closed structure can effectively prevent external dust, impurities or water vapor from entering the ranging system to pollute or block the optical surfaces of the condenser lens 4 and the return light receiver 6.
The arrangement of the band-pass filter 2 can effectively reduce the amount of ambient light energy in a non-working waveband outside the system entering the ranging system. However, stray light in the operating light band is also present in the ambient light, and the bandpass filter 2 cannot cut off this energy. In the utility model, an extinction stripe 9 is arranged on the light converging part of the optical machine chamber 5, namely between the plane end of the condenser lens 4 and the return light receiver 6. The light eliminating lines 9 are uneven lines processed on the conical inner wall of the optical machine chamber 5, so that stray light entering the working optical band of the optical machine chamber 5 can enter the light returning receiver 6 only by diffuse reflection for more times, and the energy of the stray light is weakened continuously along with the increase of the times of the diffuse reflection, thereby greatly reducing the optical bottom noise and the false alarm rate of the system. The surface of the extinction line 9 is coated with an adsorption coating of a working light wave band, when stray light of the working light wave band is reflected on the surface of the adsorption coating, more than 90% of energy is absorbed by the coating, and the energy of diffuse reflection is reduced, so that the optical background noise and the false alarm rate of the system are further reduced.
While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the utility model as defined in the appended claims.
Claims (8)
1. The utility model provides a coaxial optical system for laser rangefinder, its characterized in that, includes conical light machine room, light machine room upper portion is provided with the condensing lens, the centre bore has been seted up at the center of condensing lens, be provided with the collimating mirror in the centre bore of condensing lens, the condensing lens optical axis with the collimating mirror optical axis is coaxial, condensing lens side cover is equipped with and is used for the condensing lens clamping ring to the condensing lens axial fixity, the inside of light machine room is provided with the extinction line, light machine room lower part is provided with back light receiver, back light receiver lower part is provided with adjusting shim.
2. The coaxial optical system for laser ranging according to claim 1, wherein the convex surface of the condenser lens is provided with a band-pass filter, and the band-pass filter is sleeved outside the collimating lens.
3. The coaxial optical system for laser ranging according to claim 1, wherein the collimating lens is fixedly arranged on a central hole of the collecting lens, an outer diameter of the collimating lens barrel is matched and matched with a diameter of the central hole of the collecting lens, and a flange is arranged on the collimating lens barrel.
4. The coaxial optical system for laser ranging according to claim 1, wherein the convex end and the planar end of the condenser lens are coated with antireflection films.
5. The coaxial optical system for laser ranging according to claim 1, wherein a return light receiver motherboard is provided at a lower portion of the return light receiver.
6. The coaxial optical system for laser ranging according to claim 1, wherein a center hole is formed in the center of the band pass filter, and the diameter of the center hole of the band pass filter is matched with the outer diameter of the collimating lens barrel.
7. A coaxial optical system for laser ranging as claimed in claim 1, wherein the light sensing surface of the return light receiver is disposed at a focal point of a condenser lens.
8. The coaxial optical system for laser ranging of claim 1, wherein the extinction mark surface is coated with an absorptive coating of an operating optical band.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202122146546.6U CN216083083U (en) | 2021-09-06 | 2021-09-06 | Coaxial optical system for laser ranging |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202122146546.6U CN216083083U (en) | 2021-09-06 | 2021-09-06 | Coaxial optical system for laser ranging |
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| CN216083083U true CN216083083U (en) | 2022-03-18 |
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| CN202122146546.6U Active CN216083083U (en) | 2021-09-06 | 2021-09-06 | Coaxial optical system for laser ranging |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024207875A1 (en) * | 2023-04-07 | 2024-10-10 | 上海禾赛科技有限公司 | Rotating mirror support, rotating mirror unit and laser radar |
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2021
- 2021-09-06 CN CN202122146546.6U patent/CN216083083U/en active Active
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2024207875A1 (en) * | 2023-04-07 | 2024-10-10 | 上海禾赛科技有限公司 | Rotating mirror support, rotating mirror unit and laser radar |
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