CN113433710A - Polarization beam splitting system - Google Patents
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- G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
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Abstract
The invention provides a polarization beam splitting system. The polarization beam splitting system comprises a light emitter, a polarization beam splitter, a light sensor and a signal processing circuit. Firstly, a light emitter emits pulsed light with a preset polarization direction, then a polarization beam splitter divides the pulsed light with the preset polarization direction into first pulsed light with a first polarization direction and second pulsed light with a second polarization direction, then an optical sensor senses the pulsed light reflected by an object to output a first sensing signal and a second sensing signal, then a signal processing circuit determines a pulse signal according to the first sensing signal and the second sensing signal, and finally determines depth information of the sensed object according to the pulsed light and the pulse signal.
Description
Technical Field
The invention relates to the technical field of polarization beam splitting, in particular to a polarization beam splitting system.
Background
Face recognition is one of the popular subjects of research in the fields of pattern recognition, image processing, cognitive science and the like in recent years, and is widely applied to various aspects such as public security (criminal recognition and the like), security verification systems, credit card verification and the like, and meanwhile, with the progress of smart phones, the security function of smart phones also enters the face recognition technology era nowadays. Time-of-flight ranging (ToF) is an active 3D scanning technique that is frequently applied in recent years, mainly because of its large range of measurable distances, high resolution, and low software complexity, and is beneficial to market expansion and technology development. The sensing technology of the time-of-flight ranging method is to add another sensing component capable of measuring depth information on the traditional image sensor, wherein the component is used for calculating the depth information by sensing the time change received by light reflection.
In the conventional sensing technology of the time-of-flight ranging method, a non-polarized light is generally used as a light source, and in recent years, a sensing technology adopting a polarized light is gradually developed, and two light sources and a plurality of polarizing plates are required to be used so as to generate a light source with two orthogonal polarizations as a transmitting light.
However, as the smart phone becomes thinner and lighter, the number of components that can be placed in the internal space of the smart phone is reduced, and therefore how to reduce the internal components of the smart phone and the usage space occupied by the components is one of the problems that research and development staff should solve.
Disclosure of Invention
The invention aims to provide a polarization beam splitting system, which reduces the original requirement that two light sources generate two orthogonal polarized light sources to the requirement that only one light source is needed and a plurality of polaroids are not needed through a polarization beam splitter, can execute the operation of the ToF sensing technology, effectively reduces the number of used components and reduces the cost.
Another object of the present invention is to provide a polarization beam splitting system, which further includes a reflecting mirror, so as to realize the splitting of a single light source into two light sources with orthogonal polarizations, and further reduce the space required for the polarization beam splitting system according to the present invention by adjusting the distance between the polarization beam splitter and the reflecting mirror to correspond to the reaction time of the optical sensor.
Another objective of the present invention is to provide a polarization splitting method, which includes a selecting step and an adjusting step, wherein after a light sensor with a fixed resolution is selected, a distance between a polarization beam splitter and a reflecting mirror is adjusted, so that a time for light to pass through the distance is greater than or equal to a response time of the light sensor, thereby improving a sensing accuracy of the light sensor.
To achieve the above object, the present invention provides a polarization splitting system, comprising: a light emitter which emits pulsed light having a preset polarization direction; the polarization beam splitter is arranged in front of the light emitter, receives the pulse light with the preset polarization direction, and divides the pulse light with the preset polarization direction into a first pulse light with a first polarization direction and a second pulse light with a second polarization direction, wherein the first polarization direction is orthogonal to the second polarization direction; the optical sensor is used for sensing the reflected first pulse light and the second pulse light; and a signal processing circuit coupled to the light emitter and the light sensor.
The light emitter according to the present invention may be a laser, a light emitting diode or an organic light emitting diode.
According to the light emitter of the present invention, it is possible to generate harmonic laser light or excimer laser light as the pulse light.
Preferably, in the embodiment of the present invention, the light emitter may use a surface emitting laser (VCSEL), and the polarization direction of the emitted light by the VCSEL is elliptically or circularly polarized.
The polarization beam splitter according to the first embodiment of the present invention may be made of a birefringent material, and when the light with the polarization direction of elliptical polarization or circular polarization passes through the birefringent material, the light is divided into two mutually orthogonal polarized lights, the two polarized lights proceed in the same direction after passing through the birefringent crystal, and the two polarized lights have a distance, which varies with different parameters of the birefringent crystal.
Preferably, the polarization beam splitter according to the second embodiment of the present invention includes: and the polarization beam splitter prism is used for splitting the light with the polarization direction of elliptical polarization or circular polarization into a first pulse light with a first polarization direction and a second pulse light with a second polarization direction after the light passes through the polarization beam splitter prism, wherein the first polarization direction is orthogonal to the second polarization direction, and the advancing direction of the first pulse light is vertical to the advancing direction of the second pulse light.
According to the above configuration, the polarization beam splitter according to the second embodiment of the present invention further includes a mirror for changing the traveling direction of the pulsed light, wherein the mirror is spaced apart from the polarization beam splitter by a distance and is adjusted to an appropriate distance according to the response time of the light sensor.
According to the above configuration, the polarization beam splitter according to the second embodiment of the present invention further includes an attenuation sheet located where the polarization splitting prism emits the first pulse light, and disposed opposite to the first polarization splitting prism.
Preferably, a polarization beam splitter according to a third embodiment of the present invention includes:
the first polarization beam splitter prism is arranged in front of the light emitter, receives the pulse light with the preset polarization direction, and splits the pulse light with the preset polarization direction into the first pulse light with the first polarization direction and the second pulse light with the second polarization direction;
the second polarization beam splitter prism is positioned at the position, where the first polarization beam splitter prism emits the second pulse light, and is arranged opposite to the first polarization beam splitter prism, the first polarization beam splitter prism and the second polarization beam splitter prism are separated by a first distance, and the second polarization beam splitter prism is used for receiving the second pulse light and reflecting the second pulse light into third pulse light with a third polarization direction;
the first wave plate is arranged between the position where the second polarization splitting prism emits the third pulse light and the reflecting mirror, and the third pulse light with the third polarization direction passes through the first wave plate and then is changed into fourth pulse light with a fourth polarization direction;
the reflector and the second polarization beam splitter prism are separated by a second distance, and when the reflector reflects the fourth pulse light to the second polarization beam splitter prism, the fourth pulse light is changed into fifth pulse light with a fifth polarization direction through the first wave plate again, and the second polarization beam splitter prism divides the fifth pulse light into sixth pulse light with a sixth polarization direction;
the second wave plate is positioned at the position where the second polarization splitting prism emits the sixth pulse light and is arranged opposite to the second polarization splitting prism, the sixth pulse light is changed into seventh pulse light with a seventh polarization direction after passing through the second wave plate, and the advancing direction of the seventh pulse light is parallel to the advancing direction of the first pulse light; wherein the first polarization direction is orthogonal to the sixth polarization direction.
According to the above structure, the first wave plate of the third embodiment of the present invention is a quarter wave plate, and the second wave plate is a half wave plate.
According to the above configuration, the polarization beam splitter according to the third embodiment of the present invention further includes an attenuation sheet located where the first polarization splitting prism emits the first pulse light, and disposed opposite to the first polarization splitting prism.
Further, the present invention provides a method for performing a polarization beam splitting system, comprising the steps of: a selection step, selecting a light sensor with a certain resolution according to the requirement of a user; an adjustment step, adjusting the distance between the polarization beam splitter and the reflector according to the optical sensor selected by the user; a transmitting step of transmitting pulsed light having a preset polarization direction by a light emitter; a light splitting step of splitting the pulsed light into a first pulsed light with a first polarization direction and a second pulsed light with a second polarization direction by a polarization beam splitter, wherein the first polarization direction is orthogonal to the second polarization direction, and the traveling direction of the first pulsed light is parallel to the second pulsed light; a sensing step of sensing the pulsed light reflected by the sensing object by the optical sensor to output a first sensing signal and a second sensing signal; an operation step, determining the depth information of the sensing object according to the pulse light and the pulse signal.
According to the signal processing circuit of the present invention, the pulse signal is determined according to the first sensing signal and the second sensing signal. The signal processing circuit calculates depth information of the sensing object according to the pulsed light and the pulse signal, and the signal processing circuit may be a digital circuit or an analog circuit.
To sum up, the polarization beam splitting system and the method thereof provided by the present invention mainly utilize the polarization beam splitting system and the method thereof, so that the user can divide the pulse light with the preset polarization direction into two orthogonal polarization light sources under the condition of only using a single light source, so as to execute the operation of the ToF sensing technology, thereby achieving the purposes of reducing the use space, having wide applicability, saving the cost, etc.
For the purpose of promoting an understanding of the principles of the invention, reference will now be made in detail to the embodiments illustrated in the drawings and specific language will be used to describe the same.
Drawings
FIG. 1 is a schematic diagram of a polarization beam splitting system provided for the present invention;
FIG. 2 is a schematic diagram of a polarization beam splitter provided in accordance with a first embodiment of the present invention;
FIG. 3 is a schematic diagram of a polarization beam splitter provided in accordance with a second embodiment of the present invention;
FIG. 4 is a schematic diagram of a light sensor for receiving pulsed light according to an embodiment of the present invention;
FIG. 5 is a schematic diagram illustrating the resolution of a light sensor provided in accordance with an embodiment of the present invention;
FIG. 6 is a flow chart illustrating steps of a method of performing a polarization splitting system provided by the present invention;
FIG. 7 is a schematic diagram of a polarization beam splitter provided for a second embodiment of the present invention;
FIG. 8 is a schematic diagram of a polarization beam splitter provided in accordance with a third embodiment of the present invention;
fig. 9 is a schematic diagram of a polarization beam splitter according to a third embodiment of the present invention.
Description of reference numerals:
100-a polarization beam splitting system; 110-a light emitter; 120-polarization beam splitter; 121-a mirror; 122-a polarization splitting prism; 123-attenuation sheet; 124-a first polarization splitting prism; 125-a second polarization splitting prism; 126-a first waveplate; 127-a second wave plate; 130-a light sensor; 140-signal processing circuitry; 150-a sensing target; 220-a birefringent crystal; d-spacing; d1 — first pitch; d2 — second spacing; an L-distance; r-pulsed light; r1-first pulsed light; r2 — second pulsed light; r3-third pulsed light; r4-fourth pulse light; r5-fifth pulse light; r6-sixth pulse light; r7-seventh pulsed light; s1-selecting step; s2, an adjusting step; s3-transmitting step; s4-sensing step; s5-calculating step; t-time difference; w-thickness; x-travel distance.
Detailed Description
The embodiments of the present invention will be described in more detail with reference to the drawings and the reference numerals, so that those skilled in the art can implement the embodiments after studying the specification.
However, the present authoring is not limited to the embodiments disclosed herein but will be implemented in various forms.
The following embodiments are provided only as examples so that those having ordinary skill in the art can fully understand the disclosure of the present authoring and the scope of the present authoring disclosure.
Accordingly, the invention is not to be restricted except in light of the attached claims.
In the drawings for describing various embodiments of the present invention, the illustrated shapes, sizes, ratios, numbers, etc. are merely exemplary, and the present invention is not limited thereto.
In the present specification, the same reference numerals generally denote the same components.
Any reference to a single may encompass a plurality, unless explicitly stated otherwise.
Fig. 1 is a schematic diagram of a polarization splitting system according to the present invention. The polarization splitting system 100 shown in fig. 1 includes: a light emitter 110, a polarization beam splitter 120, a light sensor 130, and a signal processing circuit 140. The light emitter 110 may be a laser, a light emitting diode, or an organic light emitting diode, and the light emitter 110 may generate a harmonic laser light or an excimer laser light as the pulse light R, specifically, the light emitter 110 may be a surface emitting laser that emits a pulse light with a polarization direction of elliptical polarization or circular polarization.
Further, a polarization beam splitter 120 is disposed in front of the light emitter 110, and the polarization beam splitter 120 is configured to receive the pulsed light R emitted by the light emitter 110 and having a preset polarization direction, and split the pulsed light R into a first pulsed light R1 having a first polarization direction and a second pulsed light R2 having a second polarization direction, wherein the first polarization direction is orthogonal to the second polarization direction.
Specifically, the light Sensor 130 may be, for example, a complementary metal oxide semiconductor Image Sensor (CIS), and the light Sensor 130 is configured to sense a plurality of pulsed light simultaneously, and sense the first pulsed light R1 and the second pulsed light R2 reflected by the object through the light Sensor 130. Signal processing circuit 140 may be a digital circuit or an analog circuit, and signal processing circuit 140 is coupled to light emitter 110 and light sensor 130.
FIG. 2 is a schematic diagram of a polarizing beam splitter according to a first embodiment of the present invention; the polarizing beam splitter 120 may be a birefringent crystal 220 (e.g., calcite), as shown in figure 2, pulsed light R having a predetermined direction (e.g. circular polarization or elliptical polarization) emitted from the light emitter 110 is received by the polarization beam splitter 120, and divides it into a first pulse light R1 with a first polarization direction and a second pulse light R2 with a second polarization direction, wherein the first polarization direction is orthogonal to the second polarization direction, and the first pulse light R1 and the second pulse light R2 leave the birefringent crystal 220 and then travel in the same direction, it should be further described that a distance L exists between the first pulse light R1 and the second pulse light R2, when the distance L is too small, the optical sensor cannot effectively identify the two pulse lights, the distance L changes along with the thickness T of the crystal, and when the thickness T of the crystal is larger, the distance L is gradually larger, and the distance L and the thickness T of the crystal are in positive correlation.
However, the present invention is not limited thereto, and fig. 3 is a schematic view of a polarization beam splitter according to a second embodiment of the present invention; as shown in fig. 3, the polarization beam splitter 120 according to the second embodiment of the present invention may further include a mirror 121 and a polarization beam splitter prism 122. The polarization beam splitter 122 can split the incident pulse light R into a first pulse light R1 with a first polarization direction and a second pulse light R2 with a second polarization direction. The first pulse light R1 with the first polarization direction penetrates the polarization beam splitter 122, the second pulse light R2 with the second polarization direction is reflected by the polarization beam splitter 122, the first pulse light R1 is perpendicular to the traveling direction of the second pulse light R2 after leaving the polarization beam splitter 122, the first polarization direction is orthogonal to the second polarization direction, and then the traveling direction of the second pulse light R2 is changed by the reflector 121, so that the first pulse light R1 and the second pulse light R2 both travel in parallel and face the same direction.
It should be further noted that the difference between the polarization beam splitter 120 according to the second embodiment of the present invention and the first embodiment is that, when the polarization beam splitter 120 is a birefringent crystal, the optical sensor cannot effectively recognize two pulsed lights when the distance L is too small, so that the crystal thickness T must have a larger thickness, and further needs to occupy a larger usage space. On the other hand, when the polarization beam splitter 120 uses the reflecting mirror 121 and the polarization beam splitter prism 122, the usage space occupied by the polarization beam splitting system 100 according to the present invention can be effectively reduced because the polarization beam splitter is not affected by the crystal thickness T, so as to achieve the purposes of reducing the usage space and saving the cost.
Specifically, as shown in fig. 3, where the thickness of the polarization beam splitter 122 is w, the traveling distance between the first pulse light R1 and the second pulse light R2 is X, and the mirror 121 and the surface of the polarization beam splitter 122 have a distance d therebetween, such that the distance d causes an optical path difference between the first pulse light R1 and the second pulse light R2. Specifically, assuming that the refractive index of the polarization beam splitter 122 is n, when the first pulse light R1 travels by a distance X, the optical path length of the first pulse light R1 is as shown in formula (1), and similarly, when the second pulse light R2 travels by a distance X, the optical path length of the second pulse light R2 is as shown in formula (2), and thus the optical path length difference generated between the first pulse light R1 and the second pulse light R2 is as shown in formula (3).
Fig. 4 and 5 are schematic diagrams illustrating a light sensor receiving pulsed light and its resolution according to an embodiment of the present invention; referring to fig. 4, the light sensor receives the first pulse light R1 and the second pulse light R2 with a time difference T from being emitted to sensing reflection, so that the optical path difference between the first pulse light R1 and the second pulse light R2 can be converted according to the following relation between the interval d and the time difference T in formula (4) under the condition that the light speed (c) is constant. Specifically, the optical sensor 130 according to the embodiment of the present invention can be a single-point sensor, as shown in fig. 5, the response speed of the optical sensor 130 can reach 100M to 10G frequency (Frame rate), and the time difference between two laser beams needs to be greater than or equal to the time resolution of the optical sensor 130 to prevent the optical sensor 130 from being misaligned. Therefore, the time interval when the light sensor receives the first pulse light R1 and the second pulse light R2 is the time difference T, wherein the time difference T must be greater than or equal to the reaction time of the light sensor 130.
Specifically, referring to fig. 3, the Frame rate of the optical sensor 130 according to the embodiment of the present invention is 10G (corresponding time is 0.1ns), and by the derivation of the formula (4), when the light velocity (c) is a constant value, the distance between the mirror 121 and the polarization splitting prism 122 when the optical sensor 130 with the reaction velocity of 10G is used can be obtained
At least 30(mm) or more.
Referring to fig. 6 in conjunction with fig. 1 and 3, a flowchart illustrating a method for implementing the polarization beam splitting system of the present invention is shown, and the following steps can be performed.
First, in the selecting step S1, the signal processing circuit 114 inputs the response speed and resolution of the optical sensor 130 used by the user, so as to transmit the information to the polarization beam splitter 120.
Next, the process proceeds to an adjusting step S2, in which the polarization beam splitter 120 adjusts the distance d between the mirror 121 and the polarization beam splitter prism 122 according to the response speed and resolution of the light sensor 130 input by the user, so that the light sensor 130 receives the first pulse light R1 and the second pulse light R2 from the time of being emitted to the time of sensing the reflection, and the time difference T between the two times is greater than or equal to the response time of the light sensor 130.
Then, the process proceeds to the emitting step S3, and a voltage signal is emitted through the signal processing circuit 114 under the control of the user, and the light emitter 110 emits pulsed light with a predetermined polarization direction according to the voltage signal, and the pulsed light R with the predetermined polarization direction is divided into a first pulsed light R1 with a first polarization direction and a second pulsed light R2 with a second polarization direction after passing through the polarization beam splitter 120.
Further, in the sensing step S4, the light sensor 130 is activated and continues to sense while the signal processing circuit 114 is controlled by the user to emit the voltage signal, so as to receive the first pulse light R1 and the second pulse light R2 reflected by the sensing object 150 and output the first voltage signal and the second voltage signal.
Finally, proceeding to the calculation step S5, the signal processing circuit 140 may calculate the distance between the time-of-flight ranging sensor 130 and the sensing target 150 according to the first voltage signal, the second voltage signal, and the time difference between the occurrence time of the light emitter 120 emitting pulsed light R.
It should be further noted that, according to the embodiment of the present invention, the background noise signal caused by the natural light in the environment can be eliminated only by simple subtraction operation without complex software operation, so as to effectively reduce the processing time of the signal processing circuit 140 and reduce the software complexity.
Preferably, as shown in fig. 7, the polarization beam splitter 120 according to the second embodiment of the invention further includes an attenuation sheet 123, and the attenuation sheet 123 is disposed at the position where the polarization beam splitter 122 emits the first pulse light R1 and is used for adjusting the intensity of the first pulse light R1 so as to make the intensities of the first pulse light R1 and the second pulse light R2 consistent.
However, the present invention is not limited thereto, and fig. 8 is a schematic view of a polarization beam splitter according to a third embodiment of the present invention; as shown in fig. 8, the polarization beam splitter 120 according to the third embodiment of the present invention may include:
a first polarization beam splitter prism 124 disposed in front of the light emitter 110, wherein the first polarization beam splitter prism 124 receives the pulse light R with a predetermined polarization direction and splits the pulse light R with the predetermined polarization direction into the first pulse light R1 with a first polarization direction and a second pulse light R2 with a second polarization direction;
a second polarization beam splitter prism 125, which is located at the position where the first polarization beam splitter prism 124 emits the second pulse light R2 and is arranged opposite to the first polarization beam splitter prism 124, and the first polarization beam splitter prism 124 and the second polarization beam splitter prism 125 are separated by a first distance D1, wherein the second polarization beam splitter prism 125 is configured to receive the second pulse light R2 and reflect the second pulse light R2 as a third pulse light R3 with a third polarization direction;
a first wave plate 126 interposed between the position where the second polarization splitting prism 125 emits the third pulse light R3 and the mirror 123, and the third pulse light R3 having the third polarization direction passes through the first wave plate 126 and becomes the fourth pulse light R4 having the fourth polarization direction; wherein, the reflector 123 is spaced apart from the second polarization splitting prism 125 by a second distance D2, and when the reflector 123 reflects the fourth pulse light R4 to the second polarization splitting prism 125, the fourth pulse light R4 is changed into a fifth pulse light R5 with a fifth polarization direction through the first wave plate 126 again, and the second polarization splitting prism 125 divides the fifth pulse light R5 into a sixth pulse light R6 with a sixth polarization direction;
a second wave plate 127 which is located at a position where the second polarization splitting prism 125 emits the sixth pulse light R6 and is disposed opposite to the second polarization splitting prism 125, wherein the sixth pulse light R6 becomes a seventh pulse light R7 having a seventh polarization direction after passing through the second wave plate 127, and the traveling direction of the seventh pulse light R7 is parallel to the traveling direction of the first pulse light R1; wherein the first polarization direction is orthogonal to the sixth polarization direction.
Specifically, according to the polarization beam splitter of the third embodiment of the present invention, wherein the first polarization beam splitter prism 124 may be the same as the second polarization beam splitter prism 125, the first wave plate 126 may be a quarter wave plate, and the second wave plate 127 may be a half wave plate.
In this way, the pulse light emitted by the light emitter 110 with the predetermined polarization direction passes through the first polarization splitting prism 124 and is then divided into the first pulse light with the first polarization direction and the second pulse light R2 with the second polarization direction, wherein the traveling directions of the first pulse light R1 and the second pulse light R2 are perpendicular to each other. Next, the second pulse light R2 enters the second polarization beam splitter prism 125, and since the first polarization beam splitter prism 124 is the same as the second polarization beam splitter prism 125, the second pulse light R2 cannot penetrate the second polarization beam splitter prism 125 and is reflected to the opposite direction of travel to the first pulse light R1. After the second pulse light R2 passes through the quarter wave plate, the polarization direction of the second pulse light R2 is rotated by 45 degrees, and after the second pulse light R2 passes through the quarter wave plate again after being reflected by the mirror 121, the polarization direction of the second pulse light R2 is rotated by 45 degrees again, so the polarization direction of the second pulse light R2 is rotated by 90 degrees in total, and the polarization direction of the second pulse light R2 is consistent with the polarization direction of the first pulse light R1 and has the same amplitude, that is, the polarization direction of the second pulse light R2 is rotated by 90 degrees in total and then becomes the first pulse light R1, and therefore, the second pulse light R2 can directly penetrate through the second polarization beam splitter 125 without being reflected. Finally, the first pulse light R1 transmitted through the second polarization splitting prism 125 passes through a half wave plate and is converted back to the second pulse light R2, so as to generate two light sources with orthogonal polarization as emission light of ToF.
It should be further noted that in many practical applications, the distance d in the second embodiment according to the present invention needs to be reduced to a smaller size, so that if the distance d cannot meet the user's requirement, the optical path beyond the distance d needs to be extended. The difference between the polarization beam splitter 120 according to the third embodiment of the present invention and the polarization beam splitter 120 according to the second embodiment of the present invention is that the first polarization beam splitter 124 is separated from the second polarization beam splitter 125 by a first distance D1, and the reflector 123 is separated from the second polarization beam splitter 125 by a second distance D2, such that the overall optical path can be greatly increased without excessively increasing the area of the polarization beam splitter 120.
Preferably, as shown in fig. 9, the polarization beam splitter 120 according to the third embodiment of the invention further includes an attenuation sheet 123, and the attenuation sheet 123 is disposed at the position where the first polarization beam splitter 124 emits the first pulse light R1 and is used for adjusting the intensity of the first pulse light R1 so as to make the intensities of the first pulse light R1 and the second pulse light R2 consistent.
Therefore, the present invention has the following implementation and technical effects:
first, the present invention successfully reduces the ToF sensing system, which originally needs two light sources and a plurality of polarizers to generate two orthogonal polarized light sources as emitted light, to only one light source, thereby achieving the purposes of reducing the usage space and saving the cost.
Secondly, the present invention solves the problem of too large crystal thickness when using birefringent material by the reflector 121 and the polarization splitting prism 122, and further reduces the usage space of the polarization splitting system of the present invention.
Thirdly, by using the polarization beam splitting system of the invention and matching with the method for executing the polarization beam splitting system of the invention, the user can effectively eliminate the background noise influence caused by natural light in the environment and execute the operation of the ToF sensing technology through two orthogonal polarized pulse lights, thereby further improving the precision and the practicability of distance measurement.
Fourthly, the invention further solves the problem that the preset distance d between the reflector 121 and the polarization beam splitter prism 122 is too long due to the resolution of the optical sensor by matching the polarization beam splitter prism and the wave plate, thereby greatly increasing the applicability of the invention
The foregoing describes embodiments of the present invention with reference to specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the disclosure of the present specification.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; it is intended that all such equivalent changes and modifications be included within the scope of the present invention without departing from the spirit thereof.
Claims (13)
1. A polarization splitting system, comprising:
a light emitter for emitting a pulse light having a predetermined polarization direction;
a polarization beam splitter disposed in front of the light emitter, the polarization beam splitter receiving the pulsed light with the predetermined polarization direction and splitting the pulsed light with the predetermined polarization direction into a first pulsed light with a first polarization direction and a second pulsed light with a second polarization direction, wherein the first polarization direction is orthogonal to the second polarization direction;
a light sensor configured to sense a plurality of pulsed lights simultaneously, and sense the first pulsed light and the second pulsed light reflected by a sensing object through the light sensor; and
a signal processing circuit coupled to the light emitter and the light sensor.
2. The polarization splitting system of claim 1, wherein the light emitter uses a laser light as the pulsed light.
3. The polarization splitting system of claim 1, wherein the polarization beam splitter is made of a birefringent material.
4. The polarization beam splitter system of claim 1, wherein the polarization beam splitter comprises a mirror for changing a traveling direction of the pulsed light, wherein the mirror is spaced apart from the polarization beam splitter by a predetermined distance.
5. The polarization beam splitting system of claim 4, wherein the polarization beam splitter further comprises a polarization beam splitting prism.
6. The polarization beam splitting system of claim 5, wherein the time for the light to pass through the predetermined gap after passing through the polarization beam splitter is greater than or equal to the response time of the light sensor.
7. The polarization splitting system according to claim 5, wherein a traveling direction of the first pulsed light is parallel to a traveling direction of the pulsed light, and a traveling direction of the second pulsed light is perpendicular to the traveling direction of the first pulsed light.
8. The polarization beam splitter system according to claim 5, further comprising an attenuation plate located at a position where the polarization beam splitter prism emits the first pulsed light and disposed opposite to the polarization beam splitter prism.
9. The polarization beam splitter system of claim 5, wherein the polarization beam splitter further comprises:
a first polarization beam splitter prism disposed in front of the light emitter, the first polarization beam splitter prism receiving the pulsed light with the preset polarization direction and splitting the pulsed light with the preset polarization direction into the first pulsed light with the first polarization direction and the second pulsed light with the second polarization direction;
the second polarization beam splitter prism is positioned at the position where the first polarization beam splitter prism emits the second pulse light and is arranged opposite to the first polarization beam splitter prism, and a first preset distance is reserved between the first polarization beam splitter prism and the second polarization beam splitter prism;
a first wave plate, disposed between the position where the second polarization splitting prism emits the third pulse light and the reflector, wherein the third pulse light with the third polarization direction passes through the first wave plate and is converted into a fourth pulse light with a fourth polarization direction; wherein,
the reflector and the second polarization beam splitter prism are separated by a second preset distance, and when the reflector reflects the fourth pulse light to the second polarization beam splitter prism, the fourth pulse light is changed into fifth pulse light with a fifth polarization direction through the first wave plate again, and the second polarization beam splitter prism divides the fifth pulse light into sixth pulse light with a sixth polarization direction;
a second wave plate located at the position where the second polarization beam splitter emits the sixth pulse light and disposed opposite to the second polarization beam splitter, wherein the sixth pulse light passes through the second wave plate and then becomes a seventh pulse light with a seventh polarization direction, and the traveling direction of the seventh pulse light is parallel to the traveling direction of the first pulse light, wherein the first polarization direction is orthogonal to the seventh polarization direction.
10. The polarization splitting system of claim 9, wherein a time for light to pass through the first and second predetermined spacings is equal to or greater than a response time of the light sensor.
11. The polarization splitting system according to claim 9, wherein the polarization beam splitter further comprises an attenuation plate located at a position where the first polarization splitting prism emits the first pulsed light and disposed opposite to the first polarization splitting prism.
12. The polarization splitting system of claim 9, wherein the first wave plate is a quarter wave plate.
13. The polarization splitting system of claim 9, wherein the second wave plate is a half wave plate.
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| CN202010206071.2A CN113433710A (en) | 2020-03-23 | 2020-03-23 | Polarization beam splitting system |
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| CN202010206071.2A CN113433710A (en) | 2020-03-23 | 2020-03-23 | Polarization beam splitting system |
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| CN113433710A true CN113433710A (en) | 2021-09-24 |
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