A phase-based laser ranging optical system

Abstract

This invention relates to laser ranging optical systems, and more particularly to a phase-based laser ranging optical system. A phase-based laser ranging optical system includes a transmitting unit, a local oscillator signal receiving unit, a master oscillator signal receiving unit, and a reflector. The advantages of this invention are: by using an optical fiber instead of a beam splitter, a portion of the light emitted by the diode is transmitted to the local oscillator signal point via the optical fiber. Compared to using a beam splitter to provide the local oscillator signal, this method offers advantages such as lower noise, stronger anti-interference capability, and stronger shock resistance, thereby improving the accuracy of the phase-based laser ranging system.

Description

Technical Field

[0001] This invention relates to laser ranging optical systems, and more particularly to a phase-based laser ranging optical system. Background Technology

[0002] As various industries continue to increase their demands for intelligence, the application of laser ranging technology is becoming more and more widespread, and its accuracy is also getting higher and higher. At present, there are many types of laser ranging systems used for ranging, and there are also many methods used. The most common ones are pulse method, phase method and triangulation method. Phase method laser ranging systems are playing an increasingly important role due to their high accuracy and large range.

[0003] The optical system of a phase-based laser rangefinder mainly consists of two parts: a transmitting system and a receiving system. The transmitting system provides a local oscillator signal and a master oscillator signal. The master oscillator signal is used to measure the distance, while the local oscillator signal provides a reference phase. The receiving system receives and compares the phase difference between the master oscillator signal and the local oscillator signal returned from the object being measured, thereby obtaining the measured distance. Currently, the transmitting system mainly consists of a continuous laser emitter, a collimating lens, and a beam splitter. The light emitted by the laser emitter is collimated by the collimating lens and then strikes the beam splitter, which separates the light into the master oscillator signal and the local oscillator signal.

[0004] In existing laser ranging optical systems, a beam splitter is typically used to separate the light emitted from the light source into a dominant signal and a local oscillator signal. The beam splitter is generally made of transparent or semi-transparent glass. Its working principle is that when placed, the normal of the beam splitter forms a certain angle with the light ray. When light passes through the transparent or semi-transparent glass, refraction and reflection occur. Part of the light is refracted and exits the beam splitter to form the dominant signal, while the other part is reflected by the beam splitter to the local oscillator signal receiving point to form the local oscillator signal. The advantage of this method is its simplicity and ease of installation. However, using a beam splitter to provide the local oscillator signal has the following disadvantages:

[0005] 1. Beam splitters are generally made of glass, which has poor impact resistance and is easily broken during use.

[0006] 2. In order to receive the light reflected back from the beam splitter, the local oscillator signal point needs to have a certain opening on its shield. This will reduce the shielding effect of the shield, and stray light from the optical system will also enter the local oscillator signal point, reducing the stability of the local oscillator signal and thus reducing the overall measurement accuracy.

[0007] 3. When light passes through the beam splitter, it will pass through the front and back surfaces and be reflected twice. Therefore, two local oscillator signals will reach the local oscillator signal receiving point. Since the beam splitter has a certain thickness, the two local oscillator signals that reach the signal receiving point have different phases and intensities, which causes noise in the local oscillator signal.

[0008] 4. The strength of the local oscillator signal needs to be adjusted by changing the reflectivity of the beam splitter, which is very inconvenient. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a phase-based laser ranging optical system.

[0010] This invention is achieved through the following technical solution:

[0011] A phase-based laser ranging optical system includes a transmitting unit, a local oscillator signal receiving unit, and a master oscillator signal receiving unit;

[0012] The emitting unit includes a laser emitting tube, an emitting lens, and an emitting channel. The laser emitting tube is used to emit laser light. The emitting lens is located in front of the laser emitting tube. The emitting channel is located in front of the emitting lens. A polarizer is provided in the emitting channel.

[0013] The local oscillator signal receiving unit includes an optical fiber and a local oscillator signal receiver. One end of the optical fiber is located between the transmitting lens and the transmitting channel and receives part of the laser light passing through the transmitting lens. The other end of the optical fiber is connected to the local oscillator signal receiver.

[0014] The main vibration signal receiving unit includes a receiving lens and a main vibration signal receiver.

[0015] According to the above technical solution, preferably, it also includes a reflector, which is located outside the opening at the other end of the emission channel, and the receiving lens focuses the laser emitted by the reflector onto the main oscillation signal receiver.

[0016] According to the above technical solution, preferably, it further includes a housing, the housing is provided with a transmitting lens frame, the transmitting lens is fixed in front of the laser emitting tube by the transmitting lens frame, the transmitting channel is fixedly connected to the housing, the housing is provided with an optical fiber bracket, one end of the optical fiber is fixed in front of the transmitting lens by the optical fiber bracket, the housing is provided with a receiving lens frame, and the receiving lens is mounted on the receiving lens frame.

[0017] According to the above technical solution, preferably, the laser emitting tube, the local oscillator signal receiver, and the main oscillator signal receiving unit are all connected to the circuit board.

[0018] According to the above technical solution, preferably, the transmitting lens is a collimating lens.

[0019] According to the above technical solution, preferably, the installation direction of the polarizer is the same as the polarization direction of the laser emitting tube.

[0020] The beneficial effects of this invention are: by using an optical fiber instead of a beam splitter, a portion of the light emitted by the diode is transmitted to the local oscillator signal point through the optical fiber. Compared with the method of using a beam splitter to provide the local oscillator signal, this invention has advantages such as low noise, strong anti-interference ability, and strong impact resistance, thereby improving the accuracy of the phase-based laser ranging system. Attached Figure Description

[0021] Figure 1 A schematic diagram of the front view structure of an embodiment of the present invention is shown.

[0022] Figure 2 The diagram shows the reflection effect of light on the front and back surfaces of the beam splitter according to an embodiment of the present invention.

[0023] In the diagram: 1. Laser emitter, 2. Emitting lens, 3. Emitting channel, 4. Polarizer, 5. Optical fiber, 6. Local oscillator signal receiver, 7. Reflector, 8. Receiving lens, 9. Main oscillator signal receiver, 10. Housing, 11. Circuit board. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0025] like Figure 1 As shown, the present invention provides a phase-based laser ranging optical system, comprising a transmitting unit, a local oscillator signal receiving unit, and a main oscillator signal receiving unit;

[0026] The emitting unit includes a laser emitting tube, an emitting lens, and an emitting channel. The laser emitting tube is used to emit laser light. The emitting lens is located in front of the laser emitting tube. The emitting channel is located in front of the emitting lens. A polarizer is provided in the emitting channel.

[0027] The local oscillator signal receiving unit includes an optical fiber and a local oscillator signal receiver. One end of the optical fiber is located between the transmitting lens and the transmitting channel and receives part of the laser light passing through the transmitting lens. The other end of the optical fiber is connected to the local oscillator signal receiver.

[0028] The main vibration signal receiving unit includes a receiving lens and a main vibration signal receiver.

[0029] According to the above embodiments, preferably, it also includes a reflector located outside the opening at the other end of the emission channel, and the receiving lens focuses the laser emitted by the reflector onto the main oscillation signal receiver.

[0030] According to the above embodiments, preferably, it further includes a housing, the housing is provided with a transmitting lens frame, the transmitting lens is fixed in front of the laser emitting tube by the transmitting lens frame, the transmitting channel is fixedly connected to the housing, the housing is provided with an optical fiber bracket, one end of the optical fiber is fixed in front of the transmitting lens by the optical fiber bracket, the housing is provided with a receiving lens frame, and the receiving lens is mounted on the receiving lens frame.

[0031] According to the above embodiments, preferably, the laser emitting tube, the local oscillator signal receiver, and the main oscillator signal receiving unit are all connected to the circuit board 11.

[0032] According to the above embodiments, preferably, the transmitting lens is a collimating lens.

[0033] According to the above embodiments, preferably, the installation direction of the polarizer is the same as the polarization direction of the laser emitting tube.

[0034] The working principle of this embodiment is as follows: The laser emitting tube is a red visible laser diode, which emits laser light. After being collimated by the collimating lens of the emitting lens, the laser light is directed towards the emitting channel. Part of the laser light enters the optical fiber, and the light in the optical fiber is transmitted to the local oscillator signal receiver to form a local oscillator signal.

[0035] The remaining laser beam passes through a polarizer in the emission channel and reaches a reflector. The reflector is constructed from a tiny array of cubic pyramidal prisms. Part of the beam returns along its original path, rotating 90 degrees in polarization direction. Upon entering the emission channel, the returning beam encounters the polarizer, and because its polarization direction is opposite to that of the polarizer, it is blocked, thus preventing the returning beam from interfering with the local oscillator signal.

[0036] This embodiment can employ reflector ranging, diffuse reflection ranging, and through-beam ranging. Figure 1 The diagram illustrates a distance measurement method using a reflector. The laser emitted by the reflector is focused by a receiving lens onto the master oscillation signal receiver, generating the master oscillation signal.

[0037] The beneficial effects of this invention are: using optical fiber instead of a beam splitter to provide the local oscillator signal for the system. First, optical fiber is highly resilient and not easily damaged during transportation or use, thus significantly improving the overall impact resistance of the optical system.

[0038] Secondly, when a beam splitter is used to provide the local oscillator signal for the system, the reflection effect of light on the front and back surfaces of the beam splitter is as follows: Figure 2As shown, when light passes through the beam splitter, the two reflected rays produced are in the same direction. Since both rays can reach the local oscillator signal receiver and the intensity and phase of the two reflected rays are different, the local oscillator signal point will have a large noise. Secondly, in order for the light to reach the local oscillator signal receiver, a large opening must be left above the local oscillator signal receiver, which increases the possibility of stray light entering the receiver. At the same time, a large opening is not conducive to shielding electromagnetic interference.

[0039] When using optical fiber to provide the local oscillator signal, the light transmitted through the optical fiber is continuous, and the output end of the optical fiber can be directly inserted into the shield of the local oscillator signal, making the shield more enclosed and improving its ability to resist electromagnetic interference. In addition, the enclosed shield can also block stray light from interfering with the local oscillator signal. Therefore, the local oscillator signal transmitted using optical fiber is more stable and has less noise, which significantly improves the accuracy of the entire ranging system.

[0040] Finally, the strength of the local oscillator signal can be controlled by the diameter of the optical fiber. Since the optical fiber is a standard component, it is more convenient to adjust the reflectivity of the beam splitter, and the method of changing the reflectivity of the beam splitter is more convenient and less costly.

[0041] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A phase-based laser ranging optical system, characterized in that, It includes a transmitting unit, a local oscillator signal receiving unit, and a main oscillator signal receiving unit; The emitting unit includes a laser emitting tube, an emitting lens, and an emitting channel. The laser emitting tube is used to emit laser light. The emitting lens is located in front of the laser emitting tube. The emitting channel is located in front of the emitting lens. A polarizer is provided in the emitting channel. Includes a reflector located outside the opening at the other end of the emission channel. The receiving lens focuses the laser emitted by the reflector onto the main oscillation signal receiver. Part of the beam returns along the original optical path and rotates 90 degrees in polarization direction. After the returned beam enters the emission channel, it encounters a polarizer and is blocked by the polarizer. The emission lens is a collimating lens. The local oscillator signal receiving unit includes an optical fiber and a local oscillator signal receiver. One end of the optical fiber is located between the transmitting lens and the transmitting channel and receives part of the laser light passing through the transmitting lens. The other end of the optical fiber is connected to the local oscillator signal receiver. The main vibration signal receiving unit includes a receiving lens and a main vibration signal receiver; It also includes a housing, which is provided with a transmitting lens frame. The transmitting lens is fixed to the front of the laser emitting tube via the transmitting lens frame. The transmitting channel is fixedly connected to the housing. The housing is provided with an optical fiber bracket. One end of the optical fiber is fixed to the front of the transmitting lens via the optical fiber bracket. The housing is provided with a receiving lens frame. The receiving lens is mounted on the receiving lens frame. After the laser is collimated by the collimating lens of the transmitting lens, it is directed towards the transmitting channel. Part of the laser enters the optical fiber, while the rest passes through the polarizer in the transmitting channel and reaches the reflector. The strength of the local oscillator signal is controlled by the aperture of the optical fiber.

2. The phase-based laser ranging optical system according to claim 1, characterized in that, The laser emitter, local oscillator signal receiver, and main oscillator signal receiver are all connected to the circuit board.

3. The phase-based laser ranging optical system according to claim 1, characterized in that, The polarizer is installed in the same direction as the polarization direction of the laser emitter.

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