JP2007065151A - Imaging lens - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the aberration due to a lens shape error and lens building-in error while preventing upsizing of an imaging lens and complicating of lens building-in adjustment in the imaging lens of a small size using liquid crystal variable deflection prisms. <P>SOLUTION: In the imaging lens having a lens system and an imaging element for imaging an optical image formed through the lens system, the lens system includes the first liquid crystal variable deflection prism which deflects the ray direction of the polarization component parallel to certain one axis within a plane perpendicular to the optical axis of the incident ray and the second liquid crystal variable deflection prism which deflects the ray direction of the polarization component orthogonal to the one axis of the incident ray. The lens system is constituted such that the ray direction can be changed to a prescribed direction by the first and second liquid crystal variable deflection prisms. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an imaging lens, and in particular, has a liquid crystal variable deflection prism, compensates for the shape accuracy of the lens in the direction perpendicular to the optical axis and the positional accuracy when the lens is incorporated, and prevents a decrease in lens resolution mainly due to lens incorporation errors. It relates to an imaging lens.

  Recently, mobile phones having a digital camera function (hereinafter referred to as camera-equipped mobile phones) have become widespread. From the viewpoint of portability, a mobile phone is desired to be small and light and thin. Therefore, the imaging lens mounted on the camera-equipped mobile phone is also required to be small and light and thin. In addition, the number of pixels of solid-state image sensors such as CCD sensors and CMOS sensors mounted on cameras exceeds 1 million pixels, and image sensors with millions of pixels are being commercialized. The resolution required for the imaging lens is also increasing.

  Generally, an imaging lens combines a plurality of convex lenses and concave lenses to cancel aberrations of each lens unit, reduce aberrations as a whole imaging lens, and achieve high resolution. Therefore, by increasing the number of lenses, the degree of freedom in design increases, and a high-performance imaging lens can be designed.

  On the other hand, the thinning of the imaging lens requires severe restrictions on the optical length of the imaging lens, reduces the degree of freedom in lens configuration, and makes it difficult to improve the performance of the imaging lens. If the lens optical length is limited to a short length to achieve high performance, the lens performance will tend to change sharply with respect to the lens shape error and lens mounting position error. Required. In particular, it is difficult to increase the accuracy of lens incorporation, that is, the positional accuracy between the lenses when a plurality of lenses are assembled in a lens barrel, resulting in a decrease in lens performance.

  In order to increase the accuracy of this lens assembly and prevent deterioration of lens performance, alignment work is being performed. In general alignment work, a lens or a lens group is incorporated into the lens holding member, a two-lens lens holding member is incorporated into a dedicated alignment device, and alignment is performed while checking the captured image, resulting in good performance. At the obtained position, the two lens holding members are fixed with a short-curing adhesive to guarantee the positional accuracy of each lens.

  This alignment operation takes a relatively long operation time, and a dedicated alignment device must be prepared, which increases the assembly cost. Further, since a dedicated lens holding member is used, there is a problem in that the imaging lens is increased in size.

  As another method, the lens barrel is devised, and it is composed of a holding member that holds the lens and a holding member that holds the lens. The lens is held by each member, and a combination of a convex portion and a concave portion that fits each other is used. There has been proposed a lens barrel that is provided in a plurality and can be aligned by a combination thereof (see, for example, Patent Document 1).

  As another method, a method of correcting aberration of the imaging lens using a liquid crystal correction lens has been proposed. The liquid crystal correction lens disclosed here encloses liquid crystal in a space that is crisp, applies a voltage between electrodes provided above and below the liquid crystal layer, and modulates the value of the voltage applied to the liquid crystal layer. It is made to function as a cylindrical lens with variable lens power (see, for example, Patent Document 2).

JP 11-183770 A (page 3-6, Fig. 1-4) JP-A-3-4211 (page 3-7, Fig. 1)

  However, in the imaging lens disclosed in the above-mentioned Patent Document 1, it is necessary to provide a plurality of projections and depressions for fitting together with a structure in which the lens barrel is composed of two bodies and one is accommodated in the other. It cannot be employed in a camera for a mobile phone that requires an increase in the size of the lens and requires a reduction in size and weight.

  In the imaging lens disclosed in Patent Document 2, the liquid crystal correction lens has the above-described structure, and adjusts the direction of the liquid crystal molecules by modulating the value of the voltage applied to the liquid crystal layer, thereby adjusting the refractive index. It modulates and functions as a cylindrical lens with variable lens power. Because of this principle, liquid crystal correction lenses can only correct astigmatism of variable focus lenses using uniaxial crystalline materials, and can compensate for lens performance degradation due to lens shape accuracy and position accuracy. I can't use it.

  In order to eliminate the above-mentioned problems caused by the prior art, the present invention deflects light rays with a liquid crystal variable deflection prism, compensates for lens shape accuracy and position accuracy mainly in the direction orthogonal to the optical axis, and is compact and An object is to supply an imaging lens having a resolution.

  In order to solve the above-described problems and achieve the object, an imaging lens according to the present invention is an imaging lens having a lens system and an imaging element that images an optical image formed through the lens system. A first liquid crystal variable deflection prism for deflecting the light beam direction of a polarized light component parallel to one axis in a plane perpendicular to the optical axis, and a light beam of a polarized light component orthogonal to the one axis of the incident light beam; And a second liquid crystal variable deflection prism that deflects the direction, and the first and second liquid crystal variable deflection prisms allow the light beam direction to be variably controlled in a predetermined direction.

  In the imaging lens according to the present invention, in the above-described invention, the first and second liquid crystal variable deflection prisms include a first stripe electrode and a first counter electrode that sandwich the first liquid crystal layer. In addition, a linear voltage distribution can be formed in a plane perpendicular to the optical axis of the incident light incident on the first liquid crystal layer, and each of the first and second liquid crystal variable deflection prisms can be formed. It is desirable that the first stripe electrodes are arranged so that the directions thereof are parallel to each other.

  In the imaging lens according to the present invention, in the invention described above, the first counter electrode is an annular electrode, and the first and second liquid crystal variable deflection prisms are both a variable deflection prism and a variable focus lens. It is desirable to combine these functions.

  In the imaging lens according to the present invention, in the above-described invention, the first and second liquid crystal variable deflection prisms are second stripe electrodes arranged at a predetermined angle with respect to the first stripe electrode. And a second counter electrode, and a second liquid crystal layer stacked on the first liquid crystal layer, and each second stripe electrode in each of the first and second liquid crystal variable deflection prisms It is desirable that the directions are parallel to each other.

According to these inventions, a variable prism can be constituted by the liquid crystal prism, and the deflection angle can be adjusted so as to enhance the lens performance correspondingly to the lens mounting position, so that the lens performance can be improved. Similarly, the lens shape accuracy and the lens incorporation accuracy for securing the lens performance can be relaxed, the retention can be improved, and the manufacturing cost can be reduced.

  Furthermore, in lens design, in general, in order to ease the lens eccentricity accuracy, the lens performance is designed to reduce the effect on the lens performance due to the eccentricity. The value is falling. Therefore, if the design is made on the premise of compensation by the liquid crystal variable deflection prism, such a design method becomes unnecessary, and therefore the lens peak performance can be improved.

  Furthermore, if the above-mentioned liquid crystal variable deflection prism is stacked with the stripe electrode directions orthogonal to each other, not only the beam deflection angle but also the beam deflection direction can be set arbitrarily, and the degree of freedom in compensating the lens shape accuracy and lens position accuracy. Can be increased.

  In addition, the structure of the two electrodes sandwiching the liquid crystal layer is devised, one is a striped electrode, the other is a ring-shaped electrode, a linear voltage distribution with the striped electrode, and a voltage distribution that is centrally symmetric with the ring-shaped electrode By realizing the above, it is possible to configure a liquid crystal element that functions as a variable prism and a variable lens, and that has both functions of the lens and the prism simultaneously by a composite refractive index distribution of both.

  According to the present invention, it is possible to prevent deterioration of lens performance due to lens shape accuracy and lens position accuracy in a direction perpendicular to the optical axis while preventing an imaging lens from becoming large. Thereby, there is an effect that an imaging lens having high performance such as resolution can be obtained while being small and light.

  Exemplary embodiments of an imaging lens according to the present invention will be described below in detail with reference to the accompanying drawings.

First, an example of the imaging lens according to the present invention will be described. FIG. 1 is a cross-sectional view showing an example of an imaging lens according to the present invention.
As shown in FIG. 1, the imaging lens 1 includes a first optical lens 2 that receives light from the outside, a liquid crystal variable deflection prism 3 that receives light that has passed through the first optical lens 2, and a liquid crystal variable deflection prism 3. A second optical lens 4 on which the light that has passed is provided, and a third optical lens 5 on which the light that has passed through the second optical lens 4 is incident. The light that has passed through the third optical lens 5 passes through the Ir filter 6 and forms an image on the imaging surface 7 of the solid-state imaging device 8. The Ir filter 6 is inserted for the purpose of cutting off infrared rays and reducing deterioration in image quality due to an imaging device sensitive to infrared rays.

Next, details of the liquid crystal variable deflection prism 3 will be described with reference to FIG. FIG. 2A is a cross-sectional view showing an example of the liquid crystal variable deflection prism 3.
As shown in FIG. 2A, the liquid crystal variable deflection prism 3 has, for example, three opposing transparent substrates 21a, 21b, and 21c. A counter electrode 23a made of a transparent conductive film is formed on the front side, that is, the rear surface of the transparent substrate 21a disposed on the first optical lens 2 side. A stripe electrode 24a made of a transparent conductive film is formed on the front surface of the central transparent substrate 21b, and a stripe electrode 24b made of a transparent conductive film is formed on the rear surface of the central transparent substrate 21b. .

A counter electrode 23b made of a transparent conductive film is formed on the rear side, that is, the front surface of the transparent substrate 21c disposed on the second optical lens 4 side. Between the respective counter electrodes 23a, 23b and the stripe electrodes 24a, 24b, for example, homogeneously aligned liquid crystal layers 25a, 25b are sealed, respectively. That is, the liquid crystal variable deflection prism 3 has a two-layer configuration including a front liquid crystal panel including the counter electrode 23a, the liquid crystal layer 25a, and the stripe electrode 24a, and a rear liquid crystal panel including the stripe electrode 24b, the liquid crystal layer 25b, and the counter electrode 23b. It has become.

  In addition, the liquid crystal panel on the front side and the liquid crystal panel on the rear side are orthogonal to each other, and the major axis of the liquid crystal molecules is orthogonal. In FIG. 2A, in the front liquid crystal panel, the liquid crystal molecule major axis is perpendicular to the paper surface, and in the rear liquid crystal panel, the liquid crystal molecule major axis is parallel to the paper surface. When the liquid crystal molecules stand by voltage application, the refractive index of the polarization component parallel to the major axis of the liquid crystal molecules changes. Accordingly, the front liquid crystal panel can perform phase modulation of the polarization component in the direction perpendicular to the paper surface, and the rear liquid crystal panel can perform phase modulation of the polarization component in the direction parallel to the paper surface.

  Further, the front side liquid crystal panel and the rear side liquid crystal panel are driven by the drive voltage having the same waveform. The driving voltage used here is, for example, an AC voltage that has been subjected to pulse height modulation (PHM) or pulse width modulation (PWM).

  In addition, spacers 22a and 22b are provided between the transparent substrates 21a, 21b, and 21c at the periphery as shown in the figure, and the thicknesses of the liquid crystal layers 25a and 25b are kept constant.

Next, an arrangement form of the stripe electrodes arranged on the above-described liquid crystal panel will be described. FIG. 2B is a plan view showing the structure of the stripe electrodes 24a and 24b in the liquid crystal panel described above.
As shown in FIG. 2B, the stripe electrodes 24a and 24b have a stripe-like electrode structure, and the high resistance between the stripe electrodes 24a and 24b is higher than that of the stripe electrodes. The voltage difference supplied to the electrode lead portions 27a and 27b is adjusted so that a linear voltage gradient is generated by resistance division. Here, in order to reduce the number of lead electrodes, a method of adjusting the voltage applied to each stripe electrode 24a, 24b by resistance division has been shown, but a voltage gradient is formed by individually providing a voltage to each stripe electrode. It doesn't matter.

  Various voltages are applied to the two electrode lead portions 27a and 27b connected to the stripe electrodes 24a and 24b, and there is a potential gradient on the left and right sides of the paper according to the applied voltage. That is, voltage distribution is generated in the liquid crystal layers 25a and 25b by the stripe electrodes 24a and 24b. By changing this voltage distribution, the refractive index distribution in the liquid crystal molecule major axis direction changes. Thereby, the deflection angle of the polarization component parallel to the major axis of the liquid crystal molecule can be changed. Here, each of the liquid crystal layers 25a and 25b has two layers, and the major axes of the liquid crystal molecules are orthogonal to each other, so that the polarization component that is not deflected in the first layer is similarly deflected in the second layer. Eventually, all rays can be deflected.

  Here, the stripe electrodes 24a and 24b are schematically represented by a small number. However, if the number of stripe electrodes is small, the refractive index distribution becomes stepwise and the imaging lens resolution is deteriorated. It is desirable to configure as many as possible to obtain a smooth refractive index distribution.

Further, returning to FIG. 1, the imaging lens will be described.
By the action of the liquid crystal variable deflection prism 3 described above, the light beam direction can be deflected so that the solid line shown in FIG. Here, the line shown by the solid line indicates the light beam when the liquid crystal variable deflection prism 3 is in a bare glass state without applying a voltage.

  In the case of the example shown in FIG. 1, the light beam is deflected downward in the drawing by applying a voltage. The optical lens is decentered before and after the liquid crystal variable deflection prism 3. For example, the first optical lens 2 before the liquid crystal variable deflection prism 3 is on the upper side and the second optical lens behind the liquid crystal variable deflection prism 3 is on the upper side. In the case where the fourth and third optical lenses 5 are relatively decentered downward, such a deflection has an effect of preventing resolution degradation.

Next, the lens characteristics of the imaging lens of the present invention provided with a liquid crystal variable deflection prism will be described.
FIG. 3 shows MTF (Modulation Transform Function) simulation data. The MTF shown here is generally widely used as a scale representing the lens performance, and represents the degree of contrast transmission when a repetitive pattern of a certain spatial frequency is imaged by the imaging lens. The higher the MTF, the higher the MTF. Represents a high-resolution lens. FIG. 3 shows a graph of the MTF of the lens in this example, where the horizontal axis represents the spatial frequency (cycle / mm) and the vertical axis represents MTF (%). Here, the angle of view is 15 degrees. 3 (a) shows the MTF in the design data, FIG. 3 (b) shows the MTF when the second optical lens 4 is decentered by 10 μm, and FIG. c) shows the MTF when the liquid crystal variable deflection prism is operated.

Here, the angle of view is an angle of view on the image side, and means a light ray incident at an angle of 15 degrees with respect to the lens optical axis. For example, in the case of a lens having an angle of view of ± 30 degrees, it means a light beam at a position of just 50%. In addition, the solid line and the alternate long and short dash line in the graph indicate the MTF values in the meridional direction and the sphere missing direction, respectively. The meridional direction is a direction parallel to the plane formed by the incident light beam and the optical axis, and the sphere missing direction means a direction perpendicular to the spherical missing direction. The dotted line in the graph indicates the diffraction limit of this lens.
From FIG. 3B, it can be seen that the MTF is worse than the design data (see FIG. 3A), and in particular, the meridional MTF is significantly degraded. On the other hand, even if there is the above-mentioned eccentricity by deflecting the light beam incident in a predetermined direction by the liquid crystal variable deflection prism 3 provided in the imaging lens of the present invention, as shown in FIG. An effect of improving the MTF can be obtained. Here, the refractive index difference Δn given to the liquid crystal variable deflection prism 3 is 0.15, which is a sufficiently realizable number.

Here, lens data of the first to third optical lenses, the liquid crystal variable deflection prism, and the Ir cut filter applied in this embodiment are shown.
The numerical values used in the simulation for this example are shown in Table 1 below. In the values shown in this table, the units of “curvature radius” and “surface spacing” are millimeters (mm). The “surface interval” is an interval at the center of the optical axis. For the first optical lens 2, both the front surface and the rear surface are aspherical. The same applies to the second optical lens 4 and the third optical lens 5.

  In the above description, the effect is shown only for the eccentricity of the second optical lens 4, but not only for the eccentricity of other lenses, but also for the inclination of the surface such as tilt and wedge as well as the eccentricity. However, the effect of improving the MTF can be obtained by providing an appropriate refractive index profile to the liquid crystal variable deflection prism 3. In particular, the optical lens before the liquid crystal variable deflection prism 3 is highly effective for correcting the tilt of the surface such as tilt and wedge, and the subsequent lens is effective for correcting the eccentricity.

  Although the above description is for a single cross section, a general optical lens has a rotationally symmetric shape, and it is considered that eccentricity and inclination of a surface may occur in an arbitrary direction. It is done. Therefore, by making the relative angles of the liquid crystal variable deflection prism 3 and other optical lenses arbitrarily variable, it is possible to cope with a wider range of manufacturing errors and built-in errors.

  FIG. 4 is a diagram for explaining an example. The optical lens is incorporated in a cylindrical lens barrel 42. The lens barrel 42 is fitted with a base 43 and arranged at an arbitrary angle with the optical axis as a rotation axis. It can be done.

  Thereby, the liquid crystal variable deflection prism 3 incorporated in the liquid crystal variable deflection prism holder 41 and the optical lens can be arranged at an arbitrary angle. In this example, the liquid crystal variable deflection prism 3 is located in front of the optical lens.

  In determining the relative angle between the lens barrel 42 and the liquid crystal variable deflection prism holder 41 in this apparatus configuration, it is desirable to determine an optimum position while projecting an image. In general, in assembling the lens system, there is an operation of adjusting the distance between the sensor and the lens system while viewing the image, and at this time, the angle may be determined simultaneously. In addition, since the first to third optical lenses 2, 4, and 5 are manufactured by injection molding using a mold, it is difficult to achieve accuracy as designed, but once the mold and molding conditions are determined. Thus, the shape error between the individual optical lenses is small. Therefore, if the optimum correction angle condition is set in the lens barrel, the following optical lens can be followed, and there is no need to adjust the correction angle or the like for each imaging lens. A sufficient effect can be obtained even with correction by the prism.

Next, another embodiment of the imaging lens of the present invention will be described.
In the previous embodiment, as the electrode structure for applying a voltage to the liquid crystal layers 25a and 25b, one is the stripe electrodes 24a and 24b, and the other is the solid structure counter electrodes 23a and 23b. Accordingly, only a linear voltage gradient is applied to the liquid crystal layers 25a and 25b. Here, the effect in the case where the counter electrodes 23a and 23b have the annular electrode structure as shown in FIG. 5 will be described. FIG. 5 shows a counter electrode structure, and represents an annular electrode configuration that is a collection of concentric electrodes.

  The voltage of each annular electrode 51 shown in this embodiment is given by supplying a voltage to the electrode leading portion 53b drawn from the central annular zone and the electrode leading portion 53a drawn from the outermost annular zone. Each annular electrode 51 is connected by a connecting portion 52 indicated by oblique lines, and by adjusting the resistance value of the connecting portion higher than that of each annular electrode, the voltage value of each annular electrode is divided by resistance division. Is determined. Here, in order to reduce the number of extraction electrodes, two are provided at the center and the outermost periphery, but a voltage may be supplied to each annular electrode 51 independently. Further, although the number of annular electrodes 51 is schematically shown as being small, it is desirable that the number of annular electrodes is large in order to provide a smooth refractive index distribution.

  If the refractive index of the liquid crystal layers 25a and 25b changes depending on the voltage value applied to the voltage extraction parts 53a and 53b, and the higher voltage can control the refractive index lower, the central voltage is controlled higher than the surroundings. Thus, if the concave lens is controlled in reverse, a convex lens can be formed. Thereby, the lens power can be adjusted as a whole lens system, the conjugate object side distance can be adjusted, and autofocus can be achieved. That is, by using a convex lens, an object at a closer distance can be focused, and if there is a margin in the lens power variable range, a function such as a macro is also possible.

  This makes it possible to achieve a liquid crystal element that can simultaneously achieve a liquid crystal variable power lens capable of autofocus without moving parts, and a liquid crystal variable deflection prism that can compensate for lens performance deterioration due to lens shape error and optical lens incorporation error, and has a combined function A liquid crystal device with a large thickness can be achieved, which is highly advantageous.

Next, still another embodiment of the imaging lens of the present invention will be described.
The liquid crystal variable deflection prisms shown in the first and second embodiments are uniaxial deflecting elements. However, if two liquid crystal variable deflection prisms are stacked and arranged so as to be orthogonal to each other, two orthogonal X axes Y-axis deflection can be controlled, and deflection in any direction and size can be controlled.

FIG. 6 is a schematic diagram for explaining a liquid crystal variable deflection prism capable of biaxial control.
The liquid crystal variable deflection prism 61 in the X-axis direction and the liquid crystal variable deflection prism 62 in the Y-axis direction are stacked, and the X-axis and Y-axis are deflected. The two liquid crystal variable deflection prisms 61 and 62 may have the same configuration, and only need to be arranged orthogonally. Each of the liquid crystal variable deflection prisms 61 and 62 has two liquid crystal layers and is in charge of deflecting each polarization component, but is not shown in FIG. 6 for simplicity.

  Unlike the previous embodiment in which light beams incident in one direction are deflected, it is possible to control the deflection in an arbitrary direction and size by adopting such a two-layer structure orthogonal to each other. The work such as the relative rotation arrangement with the optical lens system shown is not necessary.

In the above, this invention is not restricted to the Example mentioned above, A various change is possible. For example, the dimensions and the like described in each example are examples, and the present invention is not limited to these values. Further, according to the specification of the imaging lens, the first optical lens 2 may be composed of two or more optical lenses, and the second optical lens 4 is composed of one or three or more optical lenses. May be.

  As described above, the imaging lens according to the present invention is suitable for an imaging lens that is greatly limited in size and thickness and requires high resolution, and is particularly suitable for a mobile phone with a camera. The present invention is also applicable to cameras such as ordinary silver halide photography cameras, digital cameras, movie cameras, and rear confirmation cameras such as cars.

It is sectional drawing which shows an example of the imaging lens concerning this invention. FIG. 4 is a cross-sectional view showing an example of a liquid crystal variable deflection prism constituting the imaging lens according to the present invention and a plan view showing an electrode structure. It is a graph which shows MTF of the imaging lens concerning this invention. It is a disassembled perspective view which shows an example of the imaging lens concerning this invention. It is a top view which shows another example of the electrode structure of the liquid-crystal variable deflection | deviation prism concerning this invention. It is a typical disassembled perspective view which shows another example of the liquid-crystal variable deflection | deviation prism concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Imaging lens 2 1st optical lens 3 Liquid crystal variable deflection prism 4 2nd optical lens 5 3rd optical lens 6 Ir filter 7 Imaging surface 8 Solid-state image sensor 21a, 21b, 21c Transparent substrate 22a, 22b Spacer 23a, 23b Counter electrode 24a, 24b Stripe electrode 25a, 25b Liquid crystal layer 27a, 27b Electrode lead part 41 Liquid crystal variable deflection prism holder 42 Lens barrel 43 Base 51 Ring electrode 52 Connection part 53a, 53b Electrode lead part 61, 62 Liquid crystal variable deflection prism

Claims (4)

In an imaging lens having a lens system and an imaging element that captures an optical image formed through the lens system,
The lens system includes: a first liquid crystal variable deflection prism that deflects a light beam direction of a polarization component parallel to a certain axis in a plane perpendicular to the optical axis of the incident light beam; and the one axis of the incident light beam. A second liquid crystal variable deflection prism that deflects the light beam direction of the orthogonal polarization component,
An imaging lens characterized in that the light direction can be variably controlled in a predetermined direction by the first and second liquid crystal variable deflection prisms. The first and second liquid crystal variable deflection prisms include a first stripe electrode and a first counter electrode that sandwich the first liquid crystal layer,
A linear voltage distribution can be formed in a plane perpendicular to the optical axis of the incident light beam incident on the first liquid crystal layer;
2. The imaging lens according to claim 1, wherein the first stripe electrodes of the first and second liquid crystal variable deflection prisms are arranged so that directions thereof are parallel to each other. The first counter electrode is an annular electrode;
The imaging lens according to claim 2, wherein the first and second liquid crystal variable deflection prisms have both functions of a variable deflection prism and a variable focus lens. The first and second liquid crystal variable deflection prisms are sandwiched between a second stripe electrode and a second counter electrode arranged at a predetermined angle with respect to the first stripe electrode, A second liquid crystal layer stacked on the liquid crystal layer;
The imaging according to claim 2 or 3, wherein directions of the second stripe electrodes in the first and second liquid crystal variable deflection prisms are arranged so as to be parallel to each other. lens.

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