阅读说明：本技术 一种支持高速多波束跟踪的移动光通信装置 (Mobile optical communication device supporting high-speed multi-beam tracking ) 是由 熊明亮 刘庆文 邓浩 张清清 于 2019-10-15 设计创作，主要内容包括：本发明涉及一种支持高速多波束跟踪的移动光通信装置,该装置包括主机、多个设置在主机在空间中投射出光场内的从机以及用以实现从机跟踪定位的定位跟踪系统,所述的主机内设有用以产生光束的调制光源系统以及接收准直光束并在空间中投射出光场的全息投影系统和内部光路转向器件,所述的从机内设有用以输出信息的接收解调器。与现有技术相比,本发明具有高速率高移动性、响应速度高、定位准确、空间占用小、成本低等优点。(The invention relates to a mobile optical communication device supporting high-speed multi-beam tracking, which comprises a host, a plurality of slaves arranged in a space projection light field of the host and a positioning and tracking system used for realizing the tracking and positioning of the slaves, wherein a modulated light source system used for generating light beams, a holographic projection system used for receiving collimated light beams and projecting the light field in the space and an internal light path steering device are arranged in the host, and a receiving demodulator used for outputting information is arranged in the slaves. Compared with the prior art, the invention has the advantages of high speed, high mobility, high response speed, accurate positioning, small space occupation, low cost and the like.)

1. A mobile optical communication device supporting high-speed multi-beam tracking is characterized by comprising a host (1), a plurality of slaves (2) arranged in a space projected light field of the host (1) and a positioning and tracking system (92) used for realizing tracking and positioning of the slaves (2), wherein a modulated light source system (90) used for generating light beams, a holographic projection system (91) used for receiving collimated light beams and projecting the light field in the space and an internal light path steering device are arranged in the host, and a receiving demodulator used for outputting information is arranged in the slaves (2).

2. A mobile optical communication device supporting high-speed multi-beam tracking according to claim 1, wherein the modulated light source system (90) comprises a laser (10), a light modulator (11), a beam expander (12) and a polarizer (13) arranged in sequence, and the holographic projection system (91) comprises an image sensor (17), a main controller (18) and a spatial light modulator connected in sequence, and the spatial light modulator receives the forward light beam emitted by the modulated light source system (90).

3. A mobile optical communication device supporting high-speed multi-beam tracking according to claim 2, wherein the position tracking system (92) comprises a first telecentric cat-eye retro-reflector structure disposed in the master machine (1) and a second retro-reflector structure (93) disposed in the slave machine (2), the first telecentric cat-eye retro-reflector structure and the second retro-reflector structure (93) forming a free-space optical resonator for forming the oscillating light beam therebetween.

4. A mobile optical communication device supporting high speed multi-beam tracking according to claim 3, wherein the receiving demodulator comprises a light shielding panel (20), a light transmitting hole (21) and a photodetector (24) provided on the light shielding panel (20), and a demodulation module (25) connected to the photodetector (24), and the second retro-reflector structure (93) comprises a second lens (22) and a second rear mirror (23) sequentially provided behind the light transmitting hole (21).

5. A mobile optical communication device supporting high speed multi-beam tracking according to claim 3, wherein the receiving demodulator comprises a light shielding panel (20), a light transmitting hole (21) formed in the light shielding panel (20), a photodetector (24) formed behind the light transmitting hole (21), and a demodulation module (25) connected to the photodetector (24), and the second retro-reflector structure (93) comprises a retro-reflector (27) and a coupling device (28) sequentially disposed between the light transmitting hole (21) and the photodetector (24).

6. A mobile optical communication device supporting high speed multi-beam tracking according to claim 4 or 5, wherein the spatial light modulator is a transmissive spatial light modulator (15) or a reflective spatial light modulator (151), and the internal optical path diversion device employs a beam splitter (14) and/or a plane mirror (140).

7. A mobile optical communication device supporting high speed multi-beam tracking according to claim 6, wherein when the spatial light modulator is a transmissive spatial light modulator (15) and the internal optical path turning device is a beam splitter (14), the first telecentric cat-eye retro-reflector structure comprises a first lens (16) and a first rear mirror (19), the specific optical paths are as follows:

a forward light beam emitted by a modulated light source system (90) sequentially passes through the back surfaces of a transmission-type spatial light modulator (15) and a beam splitter (14) and then is reflected to the front surface of the beam splitter (14) by a first rear reflector (19), the beam splitter (14) guides the emitted light to a first lens (16) to form a light field in a projecting mode, a backward light beam is formed after the light beam is reflected by a second retro-reflector structure (93), the backward light beam is divided into two beams by the beam splitter (14) after passing through the first lens (16), the first beam forms an oscillating light beam through the first rear reflector (19), and the other beam is received by an image sensor (17) to achieve tracking and positioning.

8. A mobile optical communication device supporting high speed multi-beam tracking according to claim 6, wherein when the spatial light modulator is a transmissive spatial light modulator (15) and the internal optical path turning device is a back-transmissive planar mirror (140), the first telecentric cat-eye retroreflector structure comprises a first lens (16) and a first partially transmissive rear mirror (19), the specific optical paths being as follows:

a forward light beam emitted by a modulated light source system (90) sequentially passes through a transmission-type spatial light modulator (15) and the back surface of a plane reflector (140) and then is projected to form a light field through a first lens (16), the light field is reflected to form a backward light beam through a second retro-reflector structure (93), the backward light beam is received by the first lens (16) and is reflected to a first rear reflector (19) through the front surface of the plane reflector (140), a part of the light beam is reflected back by the first rear reflector (19) to form an oscillating light beam, and the other part of the light beam is transmitted through the first rear reflector (19) and is received by an image sensor (17) attached to the back surface of the first rear reflector (19) to realize tracking and positioning.

9. A mobile optical communication device supporting high speed multi-beam tracking according to claim 6, wherein when the spatial light modulator is a transmissive spatial light modulator (15) and the internal optical path turning device is a back-transmissive plane mirror (140) and a beam splitter (141), the first telecentric cat-eye retro-reflector configuration comprises a first lens (16) and a first rear mirror (19), the specific optical paths being as follows:

the light field is formed by projecting forward light beams emitted by a modulated light source system (90) through a first lens (16) after sequentially passing through a transmission-type spatial light modulator (15) and the back surface of a plane reflector (140), backward light beams are formed by reflecting the forward light beams through a second retro-reflector structure (93), the backward light beams are received by the first lens (16) and are reflected to a beam splitter (141) through the front surface of the plane reflector (140) to be divided into two beams, the first beam is sequentially reflected through a first rear reflector (19), the beam splitter (141) and the plane reflector (140) to form an oscillating light beam, and the other beam is received by an image sensor (17) to realize tracking and positioning.

10. The mobile optical communication device supporting high-speed multi-beam tracking according to claim 6, wherein when the spatial light modulator is a reflective spatial light modulator (151) and the internal optical path turning device employs a beam splitter (14), the first telecentric cat-eye retro-reflector structure comprises the first lens (16) and the reflective surface of the reflective spatial light modulator (151), and the specific optical paths are as follows:

a forward light beam emitted by the modulation light source system (90) passes through the back surface of the beam splitter (14) to enter the reflective spatial light modulator (151) and returns to the front surface of the beam splitter (14) after modulation and reflection, the beam splitter (14) guides the emitted light to the first lens (16) to form a light field in a projecting manner, a backward light beam is formed after the light is reflected by the second retro-reflector structure (93), the backward light beam is divided into two beams by the beam splitter (14) after passing through the first lens (16), the first beam is reflected by the reflecting surface of the reflective spatial light modulator (151) to form an oscillating light beam, and the other beam is received by the image sensor (17) to realize tracking and positioning.

Technical Field

The invention relates to the field of wireless optical communication, in particular to a mobile optical communication device supporting high-speed multi-beam tracking.

Background

The mobile communication technology is developed from 1G to 5G, the carrier wave adopted by the technology is higher and higher, and the frequency of the electromagnetic wave adopted in the 5G technology reaches dozens of GHz. According to shannon's law, the higher the carrier frequency of wireless communication, the larger the channel bandwidth can be provided. Therefore, future mobile communications will likely employ higher frequency electromagnetic waves to provide greater communication bandwidth. Light is also an electromagnetic wave in a frequency band of the electromagnetic spectrum, and the frequency can reach hundreds of THz, which is much higher than the frequency band adopted by the current 5G, so the light wave is an excellent carrier for the next generation of mobile communication.

Generally, schemes for implementing wireless mobile communication by using a white light LED as a light emitting device are common. However, this scheme has a problem of low received power due to the wide range of radiation characteristics of LEDs and the like. In order to make the receiver capable of receiving more power, some researches focus the light waves of the LED lamp to be directed to the receiver, and some researches directly utilize a laser as a light source generator, and these schemes face the challenge of mobility. The device disclosed in chinese patent No. CN201480074547, "free space optical communication for mobile devices", has a transmitter that uses a steerable mirror to change the direction of the emitted light beam, so that the light beam scans in space to locate and track the receiver, but the scanning speed of the device is slow.

There have also been some studies using spatial light modulators or gratings to achieve non-mechanical beam steering. The light receiving surface of the spatial light modulator is provided with a plurality of pixels which are arranged, the phase or amplitude of incident light can be changed after the incident light passes through the pixels, and the change amount can be controlled according to an external electric signal. The optical lens has the property of fourier transform, so that the light field generated by the spatial light modulator can generate any desired image after passing through the lens, which is a holographic projection. The projected pattern may have light areas and dark areas, with light energy concentrated in the light areas. The invention patent CN201810341650, "two-dimensional holographic projection display method and system" in china describes such a holographic projection mode. When implementing mobile communications using holographic projection, the transmitter need only create a bright area in the projected image to cover the receiver, which will increase the received optical power of the receiver.

Beam steering is achieved only non-mechanically with holographic projection, but the final mobility problem is not solved. How to accurately position is a problem that must be solved to achieve highly flexible mobility. The transmitter needs to know the exact position of the receiver to aim the beam at the receiver. The positioning accuracy of the general positioning scheme using radio frequency is not high, and the problems of multipath effect, mutual interference and the like exist. Another positioning scheme for identifying a mobile terminal through a camera has a problem of poor reliability, and thus is difficult to adapt to a real-time mobile communication system. Chinese patent CN201810171316, "a laser communication fast capturing and aligning method based on retroreflective characteristics" discloses that positioning is realized by using a retroreflective device installed on a receiver, and accurate alignment can be realized. But simply achieving precise alignment using a retro-reflector does not improve mobility because it takes a very large amount of time to start scanning, which is unacceptable for mobile communication systems.

Disclosure of Invention

It is an object of the present invention to overcome the above-mentioned drawbacks of the prior art and to provide a mobile optical communication device that supports high-speed multi-beam tracking.

The purpose of the invention can be realized by the following technical scheme:

a mobile optical communication device supporting high-speed multi-beam tracking comprises a host, a plurality of slaves arranged in a space projection light field of the host and a positioning and tracking system used for realizing the tracking and positioning of the slaves, wherein a modulated light source system used for generating light beams, a holographic projection system used for receiving collimated light beams and projecting the light field in the space and an internal light path steering device are arranged in the host, and a receiving demodulator used for outputting information is arranged in the slaves.

The modulation light source system comprises a laser, an optical modulator, a beam expander and a polarizer which are sequentially arranged, the holographic projection system comprises an image sensor, a main controller and a spatial optical modulator which are sequentially connected, and the spatial optical modulator receives a forward light beam emitted by the modulation light source system.

The positioning and tracking system comprises a first telecentric cat eye retro-reflector structure arranged in the host and a second retro-reflector structure arranged in the slave, wherein a free space optical resonant cavity used for forming an oscillating light beam is formed between the first telecentric cat eye retro-reflector structure and the second retro-reflector structure.

The receiving demodulator comprises a shading panel, a light hole and a photoelectric detector which are arranged on the shading panel, and a demodulation module connected with the photoelectric detector, and the second retro-reflector structure comprises a second lens and a second rear reflector which are sequentially arranged behind the light hole.

The receiving demodulator comprises a shading panel, a light hole arranged on the shading panel, a photoelectric detector arranged behind the light hole and a demodulation module connected with the photoelectric detector, and the second retro-reflector structure comprises a retro-reflector and a coupling device which are sequentially arranged between the light hole and the photoelectric detector.

The spatial light modulator is a transmission-type spatial light modulator or a reflection-type spatial light modulator, and the internal light path steering device adopts a beam splitter and/or a plane mirror.

When spatial light modulator adopts transmissive spatial light modulator and inside light path turns to the device and adopts the beam splitter, first telecentric cat eye retro-reflector structure include first lens and first rear portion speculum, specific light path as follows:

the front light beam emitted by the modulation light source system sequentially passes through the back faces of the transmission-type spatial light modulator and the beam splitter and is reflected to the front face of the beam splitter by the first rear reflector, the beam splitter guides the emitted light to the first lens to form a light field in a projecting mode, the light beam is reflected by the second retro-reflector structure to form a rear light beam, the rear light beam is divided into two beams by the beam splitter after passing through the first lens, the first beam forms an oscillating light beam through the first rear reflector, and the other beam is received by the image sensor to achieve tracking and positioning.

When the spatial light modulator adopts a transmission-type spatial light modulator and the internal light path steering device adopts a plane reflector with a transmissive back surface, the first telecentric cat-eye retroreflector structure comprises a first lens and a first rear reflector with partial transmissivity, and the specific light path is as follows:

the front light beam emitted by the modulated light source system sequentially passes through the transmission-type spatial light modulator and the back surface of the plane reflector and then is projected through the first lens to form a light field, the light field is reflected through the second retro-reflector structure to form a back light beam, the first lens receives the back light beam and is reflected to the first back reflector by the front surface of the plane reflector, one part of the light beam is reflected by the first back reflector to form an oscillating light beam, and the other part of the light beam is transmitted through the first back reflector and is received by the image sensor tightly attached to the back surface of the first back reflector to realize tracking and positioning.

When the spatial light modulator adopts a transmission-type spatial light modulator and the internal light path steering device adopts a plane reflector and a beam splitter which are transmissive on the back, the first telecentric cat-eye retroreflector structure comprises a first lens and a first rear reflector, and the specific light path is as follows:

the front light beam emitted by the modulation light source system sequentially penetrates through the transmission-type spatial light modulator and the back surface of the plane reflector and then is projected through the first lens to form a light field, the light field is reflected through the second retro-reflector structure to form a back light beam, the first lens receives the back light beam and is reflected to the beam splitter through the front surface of the plane reflector to be divided into two beams, the first beam is sequentially reflected through the first rear reflector, the beam splitter and the plane reflector to form an oscillating light beam, and the other beam is received by the image sensor to realize tracking and positioning.

When the spatial light modulator is a reflective spatial light modulator and the internal light path steering device adopts a beam splitter, the first telecentric cat eye retroreflector structure comprises a first lens and a reflecting surface of the reflective spatial light modulator, and the specific light path is as follows:

the front light beam emitted by the modulation light source system passes through the back surface of the beam splitter and enters the reflective spatial light modulator, and returns to the front surface of the beam splitter after modulation and reflection, the beam splitter guides the emitted light to the first lens to form a light field through projection, the second retro-reflector structure reflects the light to form a back light beam, the back light beam is divided into two beams by the beam splitter after passing through the first lens, the first beam is reflected by the reflecting surface of the reflective spatial light modulator to form an oscillating light beam, and the other beam is received by the image sensor to realize tracking and positioning.

Compared with the prior art, the invention has the following advantages:

the invention comprises a modulated light source system, a holographic projection system, a positioning and tracking system and a plurality of receiving and demodulating devices, thereby realizing high-speed high-mobility wireless optical communication; the invention creatively adopts the retro-reflection structure and the optical imaging device to realize a positioning and tracking system, and has extremely high response speed and reliability; the invention creatively establishes a free space resonant cavity between the master machine and the slave machine, so that a high-power oscillating light beam is spontaneously established between the master machine and each slave machine. Due to the existence of the oscillation light beam, the position of the slave computer is clearer and more obvious in the sensing image, and the positioning accuracy is greatly improved; the invention enables the positioning tracking system and the holographic projection system to be fused together through the careful design of the imaging device, and has the advantages of small occupied space and low cost.

Drawings

Fig. 1A is a schematic diagram of the structure and principle of a pyramid retroreflector.

Fig. 1B is a schematic diagram of the structure and principle of a conventional cat-eye retro-reflector.

Fig. 1C is a schematic diagram of the structure and principle of a telecentric cat-eye retroreflector.

Fig. 2 is a schematic diagram of an example structure of the present invention.

Fig. 3 is a detailed schematic diagram of the example structure of fig. 2.

Fig. 4 is a schematic diagram of a modulated light source based on controlling input current.

Fig. 5 is a schematic diagram of an implementation structure of a host in the example of fig. 2.

Fig. 6 is a schematic diagram of an implementation structure of another host in the example of fig. 2.

Fig. 7 is a schematic structural diagram of an implementation of the third host in the example of fig. 2.

Fig. 8A is a schematic diagram of an implementation structure of a slave detection and demodulation part.

Fig. 8B is a schematic diagram of an implementation structure of photodetectors on the light shielding panel distributed around the light hole.

Fig. 9 is a schematic view of an implementation structure of the photodetector on the light shielding panel above the light passing hole.

Fig. 10 is a schematic diagram of a slave-implemented configuration of a photodetector after being placed in retroreflection, including a coupling device for focusing the light beam.

The notation in the figure is:

1. host, 2, slave, 3, free space, 10, laser, 11, optical modulator, 12, beam expander, 13, polarizer, 14, beam splitter, 140, plane mirror, 141, beam splitter, 15, transmissive spatial optical modulator, 151, reflective spatial optical modulator, 16, first lens, 17, image sensor, 18, main controller, 19, first rear mirror, 190, rear mirror, 20, shutter panel, 21, clear aperture, 22, second lens, 23, second rear mirror, 24, photodetector, 25, demodulation module, 240, photodetector, 241, photodetector, 242, photodetector, 243, photodetector, 244, photodetector, 25, demodulation module, 26, wire, 27, retro-reflector, 28, coupling device, 50, first focusing spot, 60, second focusing spot, 70, 20, and 16, Biaser, 80, reflective surface, 811, incident ray, 812, reflected ray, 82, lens, 83, concave mirror, 841, incident ray, 842, reflected ray, 85, lens, 86, rear mirror, 87, pupil, 88, beam, 89, beam, 881, focused spot, 892, focused spot, 90, modulated light source system, 91, holographic projection system, 910, spatial light modulator, 911, plane with reflective properties, 912, lens, 92, position tracking system, 93, second retro reflector.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

The invention provides a mobile optical communication device supporting high-speed multi-beam tracking based on a spatial light modulator and a retro-reflector. The device comprises a master machine and a slave machine, wherein the master machine can send out a modulated light beam with information to the slave machine and keep the modulated light beam to track the slave machine all the time. To achieve the above, the apparatus includes a modulated light source system, a holographic projection system, a position tracking system, and associated receiving and demodulating devices.

The modulated light source system is a subsystem within the host computer that outputs a polarized light beam with information. The information signal input to the modulated light source system is then loaded onto the output light beam. The modulated light source system includes a light emitter, an optional beam expander, and a polarizer. The light emitter emits light beams, the light beams are expanded to a certain diameter through the beam expander, and then the light beams pass through the polarizer to generate polarized light. The positions of the beam expander and polarizer may be replaced according to different embodiments. Generally, an input light beam of the spatial light modulator should be linearly polarized light with a fixed polarization angle, so that an accurate and effective spatial light modulation effect can be ensured. Unless the spatial light modulator is provided with a polarizer, the input light beam should be converted by the polarizer in advance. The beam expander is used as an optional device and is suitable for a laser light source with small diameter, and the expansion and collimation of the beam diameter are realized.

The holographic projection system is a subsystem in a host and comprises a spatial light modulator and an optical lens group. Spatial light modulators are generally of the two types, reflective and transmissive. The physical characteristics of each pixel on the light-receiving surface of the spatial light modulator can be controlled and the amplitude or phase of the light field passing through these pixels can be varied accordingly. Thus, any desired light field can be obtained by the spatial light modulator. The light beam passes through an optical lens group after passing through the spatial light modulator. The optical lens group comprises at least one projection lens for Fourier transformation and expansion of the range of the projectable area.

The light emitted by the modulated light source system is converted by the holographic projection system to display different patterns on the projected object in the space, and the patterns comprise bright and dark areas with different shapes. The projected pattern is controlled by the input signal to the spatial light modulator and the area covered by the spot can be of any shape. With this projection system, the master can project light to several arbitrarily designated areas in space to cover multiple slaves on which the spots are displayed. The projection system has the following characteristics:

a) the space coverage of the projection system is large;

b) the light spot pattern projected to the space can be controlled at will, namely the number and the shape of the projected light spots are controllable;

c) the light spot projected to the space can move randomly;

d) the power of each spot projected into space can be controlled independently.

Based on the characteristics, the host can directionally emit multiple beams of light beams with concentrated energy to the multiple slave machines, and one-to-multiple communication is realized. Compared with a general omnidirectional radiation emitter, the optical power received by the slave is higher, so that the signal-to-noise ratio is higher. Compared with the traditional mechanical light beam rotation realized based on a micro-electro-mechanical system, the host can realize the non-mechanical light beam rotation only by changing the input of the spatial light modulator through software, so that the host has higher response speed.

The positioning and tracking system is a subsystem formed by a host machine and some devices in a slave machine, and is used for determining the position of the slave machine and controlling a light beam emitted by the host machine to always point to the direction of the slave machine, so that each slave machine can be covered by a light spot emitted by the host machine in the moving process.

At least one retro-reflector or retro-reflective array with retro-reflective properties is included in the slave portion of the position tracking system. A retro-reflector is a device having a retro-reflection function. A standard retro-reflector may cause the incident beam to reflect back in the original path, i.e. the reflected beam should coincide with the incident beam. Some examples of retro-reflectors are pyramidal retro-reflectors; a conventional cat-eye retro-reflector; a telecentric cat-eye retro-reflector; other generalized cat-eye retro-reflectors; a phase conjugate mirror; a reflective sphere mirror; a hologram retro-reflector; other devices with retroreflective properties based on optical mirrors or photonic crystals etc. The retro-reflector used in the present invention does not strictly require that the reflected beam coincide with the incident beam, but at least that the reflected beam is able to have a portion that coincides with the incident beam. Therefore, when the forward beam from the master machine is irradiated to the slave machine, a part of the beam will be reflected back to the master machine by the retro-reflector. These beams that are reflected back to the host are hereinafter referred to as backward beams.

The main machine part of the positioning and tracking system at least comprises an image sensor and a main controller. The image sensor is used to detect the position and intensity of the light beam reflected back from the machine. The main controller is used for processing signals of the image sensor and is also used for controlling the spatial light modulator. Since the light beam reflected back by the receiver has strong directivity, the image sensor in the host can easily know the position of the receiver. The distance from the host to the slave can also be obtained by continuously monitoring parameters such as the shape and the brightness of the light spot and based on a reasonable software algorithm. In addition, at least one imaging lens is provided before the light beam reaches the image sensor, and the purpose of the imaging lens includes focusing or forming a free-space optical resonant cavity to facilitate light collection by the image sensor. The imaging lens can be arranged separately, but the projection lens of the host machine for expanding the range of the projectable area can also be directly used.

Compared with the traditional scheme of receiving Signal strength Received Signal Strength indication, RSSI, arrival angle, arrival time and the like based on radio frequency, the positioning and tracking system based on the retro-reflector has the following advantages:

a) the light beam has strong directivity and is easy to identify through an image sensor;

b) the back and forth light beams are all gathered on a straight line path between the host and the slave without the interference of the multipath effect;

c) there is no interference between the multiple beams.

Based on the advantages, the positioning and tracking system has higher positioning precision and reliability.

In the host, a path that a forward light beam sent from a host light source to the slave and a backward light beam reflected from the slave to the host must pass through together comprises at least one plane with reflection property, and the plane is used for separating the backward light beam from the path of the forward light beam, so that the subsequent optical processing and the acquisition of an image sensor are facilitated. Planes with reflective properties include implementation using beam splitters or plane mirrors. This configuration directs the path of the backward beam of light to travel within the host, thereby providing room for any devices within the host that facilitate light collection by the image sensor.

The enhancement of the positioning and tracking system is to add a structure with retro-reflection property in the master machine, so that the structure and the retro-reflector of the slave machine form a free-space optical resonant cavity. Due to the retro-reflection function of the retro-reflector, the backward light beam reflected from the slave to the master can be reflected back to the slave by the retro-reflection structure in the master. The beam can then oscillate back and forth between the retro-reflective structure of the master and the retro-reflector of the slave, forming an oscillating beam. The continuously oscillating round-trip beams do not overlap and therefore have a higher optical power than the non-oscillating beam. Compared with the design that only the slave machine is provided with the retro-reflector, after the retro-reflector is added in the master machine, the light beam between the master machine and the slave machine has higher light intensity, so that the light beam is easier to detect by the image sensor, and the positioning and tracking system has better anti-interference performance. According to various embodiments, the retro-reflective structure in the host computer may be implemented by using the projection lens for expanding the range of the projectable region and a flat rear mirror, which may be a separate plane mirror or a reflective surface of the reflective spatial light modulator, in the host computer. The positioning enhancement scheme based on the free space optical resonant cavity has the following advantages:

a, the positioning precision can be increased by the collimated oscillating light beam;

b, the enhanced power of the oscillating light beam reduces the interference of the ambient light to positioning;

c, forming a focusing light spot with extremely small radius, and not needing focusing.

In the slave, some devices for receiving and demodulating are included, including a shading panel, a light hole, a photoelectric detector and a demodulation module.

The shading panel is arranged on the second retro-reflector. The shading panel is provided with a light hole, and external light beams irradiate the second retro-reflector through the light hole. The purpose of the light-transmitting holes, whether hollowed or transparent, is to allow the light beam to pass through the shading panel and impinge on the retroreflector of the slave. In various embodiments, for a slave machine employing a telecentric cat-eye retro-reflector, the location of its clear aperture should overlap at the pupil of the telecentric cat-eye retro-reflector. When a retro-reflector without a pupil is used, the size and the position of the light-transmitting hole are set to enlarge the retro-reflection field of view of the slave as much as possible.

The slave should include at least one photodetector for detecting the light beam sent by the master to the slave and then converting it into a corresponding electrical signal. In a specific embodiment, the photodetector is installed in a position that ensures continuous reception of the light beam transmitted by the master, while avoiding reception of the oscillating light beam for positioning between the master and the slave. Thus, it is optional to place a plurality of photodetectors around the aperture, or to center the photodetector in the clear aperture, but not completely block it.

The demodulation module receives the electric signal output by the photoelectric detector and acquires the information transmitted by the host computer from the electric signal. Even if multiple paths of photoelectric detector signals exist, the demodulation module can select to combine the multiple paths of signals into one path of signal through the connecting point, and then demodulation is carried out. In the above-mentioned embodiment of connecting multiple channels together, it should be ensured that the lengths of the lines conducting the signals of each channel of the photodetector to the connection point are the same, so as to avoid the error code caused by the delay difference of each channel in the high-frequency communication. The demodulation module can also demodulate each path of photoelectric detector signal respectively, and then synthesize each path of demodulated information to obtain the final output information.