CN112198733A - Light beam deflection device and method based on liquid crystal lens and liquid crystal micro-lens array - Google Patents
Light beam deflection device and method based on liquid crystal lens and liquid crystal micro-lens array Download PDFInfo
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- CN112198733A CN112198733A CN202011032662.9A CN202011032662A CN112198733A CN 112198733 A CN112198733 A CN 112198733A CN 202011032662 A CN202011032662 A CN 202011032662A CN 112198733 A CN112198733 A CN 112198733A
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- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/29—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the position or the direction of light beams, i.e. deflection
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Abstract
A light beam deflection device and a method based on a liquid crystal lens and a liquid crystal micro-lens array are provided, wherein a first lens and a second lens are arranged to form the light beam deflection device, the shapes and the apertures of light transmission areas of the first lens and the second lens are consistent, and the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens; the first lens and the second lens are arranged at intervals of the sum of the focal lengths of the first lens and the second lens, and when the emergent light beam and the incident light beam are not deflected, the optical axes of the first lens and the second lens are positioned on the same straight line; the second lens is a liquid crystal lens controlled by voltage, and the optical axis movement of the second lens can be controlled by applying control voltages with different amplitudes, phases and frequencies, so that the optical axes of the first lens and the second lens are deviated, and the deflection between the emergent light beam and the incident light beam can be realized without the movement of the lenses on the space; and when the second lens adopts the rectangular hole liquid crystal lens to form the lens array, seamless splicing can be realized, and the light energy utilization rate is improved.
Description
Technical Field
The invention belongs to the technical field of light beam deflection, relates to liquid crystal optics, electric control birefringence and a liquid crystal micro lens array, and provides a light beam deflection device based on a liquid crystal lens, a light beam deflector based on the liquid crystal micro lens array and a corresponding light beam deflection method.
Background
The liquid crystal lens is a device based on a liquid crystal material, and utilizes the birefringence characteristic of liquid crystal to form non-uniform electric field distribution through voltage control so as to enable liquid crystal molecules to be distributed along electric field lines, thereby modulating incident light and forming phase distribution similar to a glass lens. The liquid crystal lens changes the characteristics of the formed lens according to the difference of the formed electric field, and the common working area is a circular hole.
A beam deflector is a device that controls the direction of propagation of a light beam by controlling the wavefront of incident light. . Beam deflectors are used in many fiber optic switching devices in fiber optic communication systems, and typically deflect a beam by moving two lenses to shift their optical axes, the angle of deflection being determined by the amount of shift in the optical axes and the focal length of the latter lens. When the deflection angle required by us is determined, if the speed of deflecting the light beam is required to be fast, the moving amount of the lens, namely the moving amount of the optical axis, needs to be reduced, so that the focal length of the subsequent lens needs to be reduced; moreover, for the deflection of a large light beam, the light energy utilization rate of the large-aperture lens is low, so that the light beam in the light beam steering device needs to be subjected to blocking processing. However, the general glass lenses are all round holes, and the beam steering device formed by the round hole lenses cannot be completely spliced seamlessly. The other method is to use two cylindrical lens arrays to realize the function of one micro lens array, and control the two micro lens arrays to generate spatial displacement through a micro electromechanical device, so that the optical axes of the two micro lens arrays are displaced, and deflection of light rays at a certain angle and in a certain direction is realized. However, in the case where the two microlens arrays are spatially displaced, only a part of the light beam of a single lens cell in the former microlens array enters a corresponding lens cell in the latter microlens array, resulting in the absence of a part of the light beam.
Disclosure of Invention
Aiming at the problems that the circular hole lenses in the traditional light beam deflection device cannot be seamlessly spliced to cause low light energy utilization rate and the micro lens array is easy to generate spatial displacement to cause light beam loss when deflecting light beams, the invention provides the light beam deflection device based on the liquid crystal lens, the voltage with a movable optical axis is adopted to control the liquid crystal lens to form the light beam deflection device, the optical axes of two lenses in the light beam deflection device can be shifted without spatial movement, and the deflection between the emergent light beams and the incident light beams is realized; in addition, the invention also provides a lens array formed by the lenses, and seamless splicing can be realized when the rectangular hole liquid crystal lens is adopted to form the rectangular hole array of the liquid crystal micro lens, so that the problems that the traditional beam deflector needs a mechanical structure to control the lenses to move on the space and the round hole lenses cannot be spliced seamlessly are solved.
The technical scheme of the invention is as follows:
the invention provides a light beam deflection device based on a liquid crystal lens, which comprises a first lens and a second lens, wherein the shape and the aperture of a light-transmitting area of the first lens are consistent with those of a light-transmitting area of the second lens, and the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens; the first lens and the second lens are arranged at intervals of the sum of the focal lengths of the first lens and the second lens, and when the emergent light beam and the incident light beam are not deflected, the optical axes of the first lens and the second lens are positioned on the same straight line;
the second lens is a liquid crystal lens controlled by voltage, and the optical axis of the second lens can be controlled to move by applying control voltages with different amplitudes, phases and frequencies, so that the optical axes of the first lens and the second lens are deviated, and the deflection between an emergent light beam and an incident light beam is realized.
Concretely, liquid crystal lens includes the liquid crystal layer, the liquid crystal layer both sides all set gradually orientation layer, high impedance membrane, electrode layer and glass substrate from inside to outside, two the direction of friction antiparallel of orientation layer, two the part of high impedance membrane coincidence does the printing opacity is regional, two the electrode layer is located respectively the position of printing opacity regional both sides sets up four electrodes, control voltage is applyed on four electrodes.
Specifically, the first lens is a glass lens or the liquid crystal lens.
Specifically, the light beam deflection devices are cascaded to realize large-angle deflection of light beams, and an emergent light beam of the light beam deflection device cascaded at the previous stage is used as an incident light beam of the light beam deflection device cascaded at the next stage.
Specifically, when the incident light beam is unpolarized, the following two methods are adopted for processing:
the method comprises the following steps that firstly, the incident light beams pass through a polaroid and then enter the light beam deflection device, and when the light beam deflection device is cascaded, the polaroid is arranged only in front of the light beam deflection device in the first-stage cascade;
when the first lens adopts a non-liquid crystal lens, one second lens is added in the light beam deflection device, the two second lenses are attached together, and the orientation directions of the two second lenses are orthogonal; when the first lens adopts a liquid crystal lens, one first lens adopting the liquid crystal lens is added in the light beam deflection device, and one second lens is added, the two first lenses are attached together, the two second lenses are attached together, the orientation directions of the two first lenses are orthogonal, and the orientation directions of the two second lenses are orthogonal.
Based on the scheme, the invention forms the lens array by the lens, and provides a light beam deflector based on the liquid crystal micro lens array, which comprises a first lens array formed by a plurality of first lens units and a second lens array formed by a plurality of second lens units corresponding to the first lens units one by one; the shape and the aperture of the light-transmitting area of the first lens unit are consistent with the shape and the aperture of the light-transmitting area of the corresponding second lens unit, and the size ratio of the first lens unit to the corresponding second lens unit is equal to the focal length ratio of the first lens unit to the corresponding second lens unit; the first lens array and the second lens array are arranged at intervals of the sum of the focal lengths of the first lens unit and the second lens unit, and when the emergent light beam and the incident light beam are not deflected, the optical axis of the first lens unit and the optical axis of the corresponding second lens unit are positioned on the same straight line;
the second lens unit is a liquid crystal lens controlled by voltage, and the optical axis of the second lens unit can be controlled to move by applying control voltages with different amplitudes, phases and frequencies, so that the optical axes of the first lens unit and the corresponding second lens unit are deviated, and the deflection between the emergent light beam and the incident light beam is realized.
Specifically, the first lens unit is a glass lens or the liquid crystal lens.
Concretely, liquid crystal lens includes the liquid crystal layer, the liquid crystal layer both sides all set gradually orientation layer, high impedance membrane, electrode layer and glass substrate from inside to outside, two the direction of friction antiparallel of orientation layer, two the part of high impedance membrane coincidence does the printing opacity is regional, two the electrode layer is located respectively the position of printing opacity regional both sides sets up four electrodes, control voltage is applyed on four electrodes.
Specifically, the overlapped part of the two high-impedance films of the liquid crystal lens is rectangular, so that the second lens array can be formed by seamlessly splicing a plurality of second lens units, and four electrodes of the liquid crystal lens are respectively arranged on the outer sides of four sides of the rectangular light-transmitting area.
Specifically, the beam deflectors are cascaded to realize large-angle deflection of the light beam, and an emergent light beam of the beam deflector cascaded at the previous stage is used as an incident light beam of the beam deflector cascaded at the next stage.
Specifically, when the incident light beam is unpolarized, the following two methods are adopted for processing:
the method comprises the following steps that firstly, the incident light beams enter the light beam deflector after passing through a polaroid, and when the light beam deflector is cascaded, the polaroid is arranged only in front of the light beam deflector in the first-stage cascade;
when the first lens unit adopts a non-liquid crystal lens, the second lens unit is formed by jointing two liquid crystal lenses with orthogonal orientation directions; when the first lens unit adopts a liquid crystal lens, the first lens unit and the second lens unit are formed by sticking together two liquid crystal lenses with orthogonal orientation directions.
In addition, the invention also provides a light beam deflection method based on the liquid crystal lens, which can be applied to the light beam deflection device formed by the liquid crystal lens and the light beam deflector formed by the liquid crystal micro-lens array.
The technical scheme of the beam deflection method is as follows: providing a first lens and a second lens which is consistent with the shape and the aperture of a light-transmitting area of the first lens, wherein the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens; the first lens and the second lens are arranged at intervals of the sum of the focal lengths of the first lens and the second lens, and incident beams are emitted after passing through the first lens and the second lens respectively;
the second lens is selected as a voltage-controlled liquid crystal lens, and the optical axis movement of the second lens can be controlled by applying control voltages with different amplitudes, phases and frequencies; when no control voltage is applied, the optical axes of the first lens and the second lens are positioned on the same straight line, and the emergent light beam and the incident light beam are not deflected; when control voltages with different amplitudes, phases and frequencies are applied, the optical axis of the second lens correspondingly moves, so that the optical axes of the first lens and the second lens deviate, deflection between the emergent light beam and the incident light beam is realized, and the deflection angle between the emergent light beam and the incident light beam is realized
Δ d is an optical axis shift amount of the first lens and the second lens, fCoke (coke)Is the focal length of the second lens.
Specifically, the first lens and the second lens form a lens group, N lens groups are cascaded to increase a deflection angle, N is a positive integer, an emergent beam of a lens group of a previous stage of cascade is used as an incident beam of a lens group of a next stage of cascade, and a deflection angle between an emergent beam of the lens group of an ith stage of cascade and the incident beam is thetaiThen the final deflection angle is
The working principle of the invention is as follows:
the invention realizes beam deflection by utilizing a first lens and a second lens, wherein the second lens is a voltage-controlled liquid crystal lens, and the optical axis movement of the second lens can be controlled by applying control voltages with different amplitudes, phases and frequencies; the first lens can be any lens, such as a glass lens used for the first lens or a liquid crystal lens used for the first lens and the second lens, and the shape and the aperture of the light-transmitting area of the first lens are required to be consistent with the shape and the aperture of the light-transmitting area of the second lens. The first lens and the second lens are arranged in a manner of being separated by the sum of the focal lengths of the first lens and the second lens, and the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens. The optical axis of the second lens can be moved by controlling the electric field of the liquid crystal lens, namely the second lens, through the voltage, the optical axis of the first lens can be fixed and can also be moved, the purpose of deflection between the emergent light beam and the incident light beam can be achieved as long as the optical axes of the first lens and the second lens are deviated, and mechanical movement is not needed, so that all light energy of the front lens enters the rear lens, and no stray light occurs. The deflection direction of the light beam is located on a spatial plane formed by the optical axis, and the deflection angle can be obtained by the following formula:
where θ is a deflection angle, Δ d is an optical axis shift amount of the first lens and the second lens, fCoke (coke)Is the focal length of the second lens.
Two glass substrates of the rectangular hole liquid crystal lens are coated with ITO (indium tin oxide) to form an electrode pattern, the surface coated with ITO is provided with a high-impedance film and coated with polyimide to carry out rubbing orientation to form two orientation layers, the surfaces coated with ITO of the two glass substrates are opposite, and liquid crystal is filled between the surfaces. The overlapped part of the two high-impedance films is a light-transmitting area and is also a working area, when the second lens adopts a rectangular-hole liquid crystal lens, the working area is rectangular, and the stripe-shaped electrodes on the electrode layers on the two glass substrates are mutually perpendicular and are distributed on the outer sides of four sides of the rectangular working area to form four electrodes. Because the area outside the working area is very small compared with the working area, seamless splicing can be realized when the rectangular hole liquid crystal lens forms a lens array. By synchronously controlling the electric field of each liquid crystal lens unit in the liquid crystal micro lens array through voltage, the optical axis of each liquid crystal lens unit can be synchronously moved. If the optical axis of the first lens array formed by the first lens positioned in front of the optical path direction is fixed, the optical axis of the liquid crystal micro lens array positioned in back of the optical path direction moves, and the distance between the two lens arrays is the sum of the focal lengths of the first lens and the second lens, the optical axes of the two lens arrays deviate to a certain extent, so that the light beam is turned.
The invention has the beneficial effects that: the invention uses the liquid crystal lens controlled by voltage to form a light beam deflection device, controls the movement of the optical axis of the liquid crystal lens by controlling the voltage of each electrode of the liquid crystal lens, leads the optical axes of two lenses in the light beam deflection device to deviate, realizes the function of light beam steering, deflects all light beams, does not need a mechanical structure to control the movement of the lens on the space, and solves the problem of light beam deletion; in addition, seamless splicing can be realized when the rectangular-hole liquid crystal lens is adopted to form the rectangular-hole array of the liquid crystal micro lens, and the problem of low light energy utilization rate caused by the fact that the lens array is formed by the circular-hole lens is solved.
Drawings
FIG. 1 is a top view of a rectangular aperture liquid crystal lens employed in embodiments of the present invention.
Fig. 2 is a cross-sectional view of a rectangular aperture liquid crystal lens employed in an embodiment of the present invention.
Fig. 3 is a schematic structural diagram of a beam deflector based on a liquid crystal lens according to the present invention, which employs a rectangular-aperture liquid crystal lens.
Fig. 4 is a schematic diagram of the operation of the beam deflector based on the liquid crystal microlens array according to the present invention.
Fig. 5 is a diagram of interference fringes of a rectangular-aperture liquid crystal lens employed in an embodiment of the present invention with the optical axis at the center.
Fig. 6 is a diagram of four interference fringes of a rectangular aperture liquid crystal lens employed in an embodiment of the present invention after the optical axis is shifted.
Detailed Description
The technical solution of the present invention is described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It will be apparent to one skilled in the art that the present invention may be practiced without some of these specific details. The following description of the embodiments is merely intended to provide a better understanding of the present invention by illustrating examples of the present invention.
The invention uses the deviation of the optical axis between two lenses to realize the deflection between the outgoing light beam and the incoming light beam, wherein the second lens is set as a voltage-controlled liquid crystal lens, the first lens can be a common glass lens or a voltage-controlled liquid crystal lens, and the relational terms such as the first lens, the second lens and the like are only used for distinguishing one entity or operation from another entity or operation, and do not necessarily require or imply any actual relation or sequence between the entities or operations, for example, the incoming light beam can be emitted after passing through the first lens and the second lens in sequence, and can also be emitted after passing through the second lens and the first lens in sequence.
As shown in fig. 2, which is a cross-sectional view of a liquid crystal lens, the voltage-controlled liquid crystal lens includes, from inside to outside, a liquid crystal layer 1, two alignment layers 2, two high-resistance films 3, two ITO electrode layers 4 with special electrode patterns, and two glass substrates 5. Firstly, respectively plating ITO electrode layers 4 on two glass substrates, and then carrying out photoetching to obtain a required electrode pattern, such as a common stripe type electrode; then respectively plating a layer of high-resistance film 3 on the two ITO electrode layers 4, cutting the glass substrate plated with the high-resistance film 3, wherein the superposed part of the two high-resistance films 3 is a light-transmitting area and is also a working area of the liquid crystal lens; the two alignment layers 2 are obtained by coating polyimide on the two electrode layers 4 plated with high-resistance films, respectively, and then performing rubbing alignment, the rubbing directions of the upper and lower plates are parallel and opposite, and then filling liquid crystal therein to form the liquid crystal layer 1. The electrode material can be other materials besides ITO, the orientation material can be other materials besides polyimide, and the formation mode of the orientation layer can be other modes.
In some embodiments, the long sides of the cut glass substrates are perpendicular to each other to make the overlapped portion of the two high impedance films 3 rectangular, as shown in fig. 1, which is a top view of the structure of fig. 2, it can be seen that the overlapped portion between the two high impedance films 3 is a rectangular working area, and the light beam deflection principle of the present invention is described below by taking a liquid crystal lens with a rectangular hole as an example, but it should be noted that liquid crystal lenses with working areas of other shapes are also applicable to the present invention. The ITO electrode layers 4 on the left side and the right side of the rectangular working area form two electrodes, and the ITO electrode layers 4 on the upper side and the lower side of the rectangular working area form another two electrodes, namely four electrodes. When the four electrodes are not electrified, liquid crystal molecules in the liquid crystal layer 1 are arranged in parallel along the orientation direction, no deflection is generated, and no lens effect exists; when power is applied to the four electrodes, the voltage will follow a linear profile due to the presence of the high impedance film. When the four electrodes are electrified in a specific voltage relationship, electric field distribution similar to a circular hole liquid crystal lens can be generated in the central working area, liquid crystal molecules in the liquid crystal layer 1 are deflected, and phase distribution similar to a glass lens is formed. Therefore, by adjusting the amplitude, phase and frequency of the voltage applied to the control voltage, the center of the electric field distribution formed can be shifted, i.e., the optical axis of the liquid crystal lens is shifted in the lens plane.
If the incident light is unpolarized light, two methods can be adopted for processing when in use, the first method is to add a polaroid in front of the beam deflection device, and the polarization direction is consistent with the orientation direction, and if the beam deflection devices are cascaded, the polaroid is only arranged in front of the first-stage cascaded beam deflection device. In the second mode, if the first lens is a non-liquid crystal lens, only two second lenses adopting the liquid crystal lens need to be arranged and attached together, and the orientation directions of the two second lenses are orthogonal; if the first lens is also a liquid crystal lens, two first lenses adopting the liquid crystal lens are required to be arranged and attached together, and two second lenses adopting the liquid crystal lens are arranged and attached together, wherein the orientation directions of the two first lenses are orthogonal, and the orientation directions of the two second lenses are also orthogonal; because the liquid crystal lens adopted in the application can be made to be very thin, the two liquid crystal lenses are attached together to form a whole, so that the influence on the beam deflection device is not great.
Example one
As shown in fig. 3, the first lens and the second lens are disposed along the optical path direction, the first lens and the second lens are separated by the sum of the focal lengths of the first lens and the second lens, and when the outgoing beam and the incoming beam are not deflected, the optical axes of the first lens and the second lens are both located on the same straight line. In this embodiment, the first lens and the second lens are both voltage-controlled rectangular liquid crystal lenses, the optical axis of the first lens is controlled to be fixed, and the optical axis of the second lens is moved to shift the optical axes of the first lens and the second lens (although the optical axis of the first lens may be moved as long as the optical axes of the first lens and the second lens are shifted). The shape and the aperture of the first lens light-transmitting area are consistent with those of the second lens light-transmitting area, and the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens.
The optical axis shifting method is that coordinate axes are established on the lens surface, assuming that the optical axes of the two liquid crystal lenses are both at the center (ox, oy) of the coordinate axes at the initial time, the control voltage V applied to the four electrodes on the second lens before shifting1、V2、V3、V4The voltage conditions of (a) are: voltage amplitude v1＝v2＝v3＝v4Phase of
Frequency f1＝f2≠f3＝f4. The optical axis of the second lens after the shift is located at (ox)a,oya) At this time, the control voltage V is applied to the four electrodes on the second lens1a、V2a、V3a、V4aThe voltage conditions of (a) are: voltage amplitude of v1a、v2a、v3a、v4aPhase of
The frequency is not changed. Expression (1) is the effective voltage value of the second lens in the effective area, and the voltage values at the optical axes of the lenses before and after the movement should be kept equal, and we can give a proper phase value
The shifted voltage amplitude can then be obtained from the following expression.
Order:
then:
v2a＝v1at21a (3)
v4a＝v3at43a (5)
angle of deflection of outgoing beam and incoming beam
Is the amount of optical axis shift of the first lens and the second lens, fCoke (coke)Is the focal length of the second lens.
Example two
In order to illustrate the lens effect and the optical axis moving function of a single rectangular-hole liquid crystal lens, in this embodiment, the single rectangular-hole liquid crystal lens is placed in one arm of a michelson interference light path, a polarizing plate with the polarization direction the same as the liquid crystal orientation direction is placed in front of the interference light path for polarizing, light is converted into parallel light through a beam expander, then enters the polarizing plate for polarizing, then enters the interference light path to form interference fringes, and finally is imaged in a CCD. When a control voltage V of a specific voltage is applied to four electrodes of the rectangular-aperture liquid crystal lens1、V2、V3、V4When the liquid crystal display panel is used, concentric circular electric field lines are formed in the effective area to deflect liquid crystal molecules, so that a phase distribution similar to a glass lens is formed, and the control voltage V is changed1、V2、V3、V4The optical axis of the lens can be moved.
To observe the working condition of the rectangular-aperture liquid crystal lens in the second embodiment, a 457nm laser was used to test the rectangular-aperture liquid crystal lens. In this embodiment, a rectangular hole liquid crystal lens with a rectangular hole side length of 5mm is used, and when a voltage amplitude v is applied1＝v2＝v3＝v41.628V, phase
Frequency f1＝f2＝500Hz，f3＝f4When the voltage is 1kHz, interference fringes as shown in fig. 5 are observed in the CCD. At this time, the rectangular hole liquid crystal lens is similar to a glass lens with the optical axis at the center. Varying the control voltage V1、V2、V3、V4The optical axis of the liquid crystal lens is moved, and the interference fringes are shown in the figureThe optical axis is moved to the left, right, up and down, respectively, as shown in fig. 6, which shows that the optical axis can be moved to any direction by changing the voltage condition, and the amount of movement can be adjusted.
EXAMPLE III
In this embodiment, the first lens uses a glass lens, and the second lens uses a rectangular-aperture liquid crystal lens, which together form a beam deflection device. For convenience of description, in this embodiment, the focal lengths of the glass lens and the rectangular-aperture liquid crystal lens are set to be equal, and the glass lens and the rectangular-aperture liquid crystal lens are placed at a distance twice the focal length. The focal length of the rectangular hole liquid crystal lens is adjusted to be equal to that of the glass lens, the optical axis of the rectangular hole liquid crystal lens array is at the center, and the incident light beam is not deflected. And then adjusting the voltage of the rectangular hole liquid crystal lens to enable the focal length of the rectangular hole liquid crystal lens to be unchanged and the optical axis to move, wherein the incident beam is deflected, and the deflection direction angle of the incident beam is changed along with the change of the moving direction and the distance of the optical axis of the rectangular hole liquid crystal lens.
Example four
In order to realize large-angle deflection, in the first embodiment or the third embodiment, a single beam deflection device composed of the first lens and the second lens may be cascaded, an outgoing beam of the beam deflection device in the previous stage is used as an incoming beam of the beam deflection device in the next stage, and a deflection angle θ between the outgoing beam of the beam deflection device in the i-th stage and the incoming beam is set asiThen the final deflection angle is
Similarly, a polarizer may be disposed in front of the first-stage beam deflection device, and the incident beam may enter the beam deflection device after passing through the polarizer.
EXAMPLE five
Considering that glass lenses are generally circular and gaps occur during splicing, if two axicon lens arrays are used to form one lens array, the complexity of the system is increased. Therefore, in this embodiment, the rectangular-hole lc lens is spliced into the rectangular-hole lc lens array, and the first lens in the first embodiment is used as a first lens unitThe second lens in the first embodiment is taken as a second lens unit, a plurality of first lens units form a first lens array, a plurality of second lens units form a second lens array, and the first lens array and the second lens array are both liquid crystal micro lens arrays. This embodiment uses two identical and spaced apart 2fCoke (coke)When the emergent light beam and the incident light beam are not deflected, the optical axis of each first lens unit and the optical axis of the corresponding second lens unit are positioned on the same straight line, and the optical axes of all the units of the liquid crystal micro-lens array are parallel but not coincident.
In the following description, the liquid crystal beam deflector is composed of an array of rectangular-hole liquid crystal lenses shown in fig. 3 and rectangular-hole liquid crystal lenses shown in fig. 4, and a polarizing plate is disposed in front of the liquid crystal beam deflector, and the polarization direction of the polarizing plate is an alignment direction. In this embodiment, the focal lengths of the two rectangular-aperture liquid crystal micro-lens arrays are first adjusted to a suitable length, such that the focal lengths of the first lens unit and the second lens unit are equal and are not changed to be fCoke (coke)The distance between the two lens arrays is twice the focal length 2fCoke (coke)The focal lengths of the two groups of liquid crystal lenses are fixed and equal through the loaded voltage, and the magnification ratio is ensured not to change. And simultaneously, the optical axes of the two rectangular hole liquid crystal micro-lens arrays are moved to the center, and the light beams are not deflected.
The optical axis of each lens unit in the front liquid crystal micro lens array (i.e. the rectangular hole liquid crystal micro lens array 1 in fig. 4 is the first lens array) is fixed, and the optical axis of each lens unit in the rear liquid crystal micro lens array (i.e. the rectangular hole liquid crystal micro lens array 2 in fig. 4 is the second lens array) is movable. In the liquid crystal beam deflector, the voltage of the rectangular hole liquid crystal micro-lens array 2 is adjusted to ensure that the focal length is unchanged and the optical axis moves by fixing the voltage of the rectangular hole liquid crystal micro-lens array 1 to be unchanged, and the corresponding control voltage V of each rectangular hole liquid crystal lens of the second lens unit is changed1、V2、V3、V4The voltage amplitude and the phase of the second lens unit can be controlled to be in the lens positionThe plane moves. The optical axis of the rectangular-hole liquid crystal micro-lens array 1 is fixed at the center, so that the optical axis of the rectangular-hole liquid crystal micro-lens array 2 moves, the light beam deflects at the moment, the deflection direction angle of the light beam changes along with the change of the moving direction and the distance of the optical axis, the deflected light beam is on the plane formed by the optical axes of the rectangular-hole liquid crystal micro-lens array 1 and the rectangular-hole liquid crystal micro-lens array 2, and the deflection angle depends on the optical axis offset of the two liquid crystal micro-lens arrays. The light beams are totally deflected at the moment, no light beam is lost, and the deflection direction and the deflection angle are adjustable.
EXAMPLE six
By cascading the single liquid crystal beam deflector composed of the first lens array and the second lens array in the fifth embodiment, it is also possible to realize large-angle deflection of the light beam.
Although only the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the gist of the present invention within the knowledge of those skilled in the art, and the changes are included in the scope of the present invention.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and it is apparent that those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A light beam deflection device based on a liquid crystal lens is characterized by comprising a first lens and a second lens, wherein the shape and the aperture of a light-transmitting area of the first lens are consistent with the shape and the aperture of a light-transmitting area of the second lens, and the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens; the first lens and the second lens are arranged at intervals of the sum of the focal lengths of the first lens and the second lens, and when the emergent light beam and the incident light beam are not deflected, the optical axes of the first lens and the second lens are positioned on the same straight line;
the second lens is a liquid crystal lens controlled by voltage, and the optical axis of the second lens can be controlled to move by applying control voltages with different amplitudes, phases and frequencies, so that the optical axes of the first lens and the second lens are deviated, and the deflection between an emergent light beam and an incident light beam is realized.
2. The liquid crystal lens-based beam deflector according to claim 1, wherein the first lens is a glass lens or the liquid crystal lens; liquid crystal lens includes the liquid crystal layer, the liquid crystal layer both sides all set gradually orientation layer, high impedance membrane, electrode layer and glass substrate from inside to outside, two the friction direction antiparallel of orientation layer, two the part of high impedance membrane coincidence does the light transmission region is, two the electrode layer is located respectively the position of light transmission region both sides sets up four electrodes, control voltage is applyed on four electrodes.
3. The beam deflector based on the liquid crystal lens as claimed in claim 2, wherein the beam deflector is cascaded to realize large-angle deflection of the beam, and the outgoing beam of the beam deflector of the previous cascade serves as the incoming beam of the beam deflector of the next cascade.
4. The liquid crystal lens-based beam deflector according to any one of claims 1 to 3, wherein when the incident beam is unpolarized, the following two processes are adopted:
the method comprises the following steps that firstly, the incident light beams pass through a polaroid and then enter the light beam deflection device, and when the light beam deflection device is cascaded, the polaroid is arranged only in front of the light beam deflection device in the first-stage cascade;
when the first lens adopts a non-liquid crystal lens, one second lens is added in the light beam deflection device, the two second lenses are attached together, and the orientation directions of the two second lenses are orthogonal; when the first lens adopts a liquid crystal lens, one first lens adopting the liquid crystal lens is added in the light beam deflection device, and one second lens is added, the two first lenses are attached together, the two second lenses are attached together, the orientation directions of the two first lenses are orthogonal, and the orientation directions of the two second lenses are orthogonal.
5. A light beam deflector based on a liquid crystal micro-lens array is characterized by comprising a first lens array formed by a plurality of first lens units and a second lens array formed by a plurality of second lens units corresponding to the first lens units one by one; the shape and the aperture of the light-transmitting area of the first lens unit are consistent with the shape and the aperture of the light-transmitting area of the corresponding second lens unit, and the size ratio of the first lens unit to the corresponding second lens unit is equal to the focal length ratio of the first lens unit to the corresponding second lens unit; the first lens array and the second lens array are arranged at intervals of the sum of the focal lengths of the first lens unit and the second lens unit, and when the emergent light beam and the incident light beam are not deflected, the optical axis of the first lens unit and the optical axis of the corresponding second lens unit are positioned on the same straight line;
the second lens unit is a liquid crystal lens controlled by voltage, and the optical axis of the second lens unit can be controlled to move by applying control voltages with different amplitudes, phases and frequencies, so that the optical axes of the first lens unit and the corresponding second lens unit are deviated, and the deflection between the emergent light beam and the incident light beam is realized.
6. The light beam deflector based on the liquid crystal micro-lens array is characterized in that the first lens unit is a glass lens or the liquid crystal lens, the liquid crystal lens comprises a liquid crystal layer, an alignment layer, a high-impedance film, an electrode layer and a glass substrate are sequentially arranged on two sides of the liquid crystal layer from inside to outside, the friction directions of the alignment layers are antiparallel, the overlapped part of the high-impedance film is a light transmission area, the electrode layers are respectively arranged on two sides of the light transmission area and provided with four electrodes, and the control voltage is applied to the four electrodes.
7. The beam deflector based on the liquid crystal micro-lens array according to claim 6, wherein the overlapped part of the two high-impedance films of the liquid crystal lens is rectangular, so that the second lens array can be formed by seamlessly splicing a plurality of second lens units, and the four electrodes of the liquid crystal lens are respectively arranged outside the four sides of the rectangular light-transmitting area.
8. The beam deflector based on the liquid crystal micro-lens array as claimed in any one of claims 5 to 7, wherein the beam deflector is cascaded to realize large-angle deflection of the beam, and the emergent beam of the beam deflector of the previous stage is used as the incident beam of the beam deflector of the next stage;
when the incident beam is unpolarized, the following two approaches are used:
the method comprises the following steps that firstly, the incident light beams enter the light beam deflector after passing through a polaroid, and when the light beam deflector is cascaded, the polaroid is arranged only in front of the light beam deflector in the first-stage cascade;
when the first lens unit adopts a non-liquid crystal lens, the second lens unit is formed by jointing two liquid crystal lenses with orthogonal orientation directions; when the first lens unit adopts a liquid crystal lens, the first lens unit and the second lens unit are formed by sticking together two liquid crystal lenses with orthogonal orientation directions.
9. A light beam deflection method based on a liquid crystal lens is characterized in that a first lens and a second lens which is consistent with the shape and the aperture of a light-transmitting area of the first lens are arranged, and the size ratio of the first lens to the second lens is equal to the focal length ratio of the first lens to the second lens; the first lens and the second lens are arranged at intervals of the sum of the focal lengths of the first lens and the second lens, and incident beams are emitted after passing through the first lens and the second lens respectively;
the second lens is selected as a voltage-controlled liquid crystal lens, and the optical axis movement of the second lens can be controlled by applying control voltages with different amplitudes, phases and frequencies; when no control voltage is applied, the optical axes of the first lens and the second lens are positioned on the same straight line, and the emergent light beam and the incident light beam are not deflected; when control voltages with different amplitudes, phases and frequencies are applied, the optical axis of the second lens correspondingly moves, so that the optical axes of the first lens and the second lens deviate, deflection between the emergent light beam and the incident light beam is realized, and the deflection angle between the emergent light beam and the incident light beam is realized
Δ d is an optical axis shift amount of the first lens and the second lens, fCoke (coke)Is the focal length of the second lens.
10. The method for deflecting light beams based on a liquid crystal lens according to claim 9, wherein the first lens and the second lens form a lens group, N lens groups are cascaded to increase a deflection angle, N is a positive integer, an emergent light beam of the lens group of the previous cascade stage is used as an incident light beam of the lens group of the next cascade stage, and a deflection angle θ between the emergent light beam of the lens group of the ith cascade stage and the incident light beam isiThen the final deflection angle is
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| CN112198733B (en) | 2022-04-22 |
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