JPH0253035A - Plane microlens - Google Patents

Abstract

PURPOSE:To provide the plane microlens itself with an optical control function by constituting the substrate of the plane microlens by using a material which has at least one of electrooptic effect, acoustooptic effect, magnetooptical effect, thermooptic effect, and nonlinear optical effect, and applying a physical quantity corresponding to the possessed optical effect and performing optical control. CONSTITUTION:A plane Fresnel lens 3 is laminated on the substrate 2 of the microlens with variable focal length to constitute the plane microlens 1. The substrate 2 is made of electrooptic effect crystal such as LiNbO3, electrodes 4 and 5 are provided to both sides, and a power source 6 is connected to the electrodes 4 and 5. When parallel light is entered into the plane Fresnel lens 3 of this plane microlens 1, the light is converged by the plane Fresnel lens 3. When a voltage is applied to the electrodes 4 and 5 from the power source 6, an electric field is applied to the substrate 2 made of the electrooptic effect crystal to cause variation in refractive index. Consequently, the focal length is varied by turning on and off the electric field applied to the substrate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field The present invention relates to a flat microlens including a grating lens, and particularly to a flat microlens having a light control function.

(B) Prior Art A conventional flat microlens is constructed by laminating a lens layer made of an optical element organic material on a glass substrate or a plastic substrate.

(c) Problems to be Solved by the Invention The glass substrates and plastic substrates of conventional microlenses have only had the function of simply protecting the lenses. Therefore, as an optical element, it was a functional element that only had a light condensing function using a lens layer. Therefore, it is impossible to add a light control function to make the flat microlens multifunctional, and in order to control light, a separate functional element must be prepared, making the configuration complicated. was there.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a flat microlens that is a single element and also has a light control function.

(d) Means and Effects for Solving the Problems The flat microlens of the present invention has a substrate having at least one of an electro-optic effect, an acousto-optic effect, a magneto-optic effect, a thermo-optic effect, and a nonlinear optical effect. It is made of a material and has the function of controlling light by applying a physical quantity corresponding to the optical effect it possesses to the substrate.

In this flat plate microlens, when a crystal having an electro-optic effect is used as the substrate, when an electric field is applied to the substrate, the refractive index of the substrate changes due to the electro-optic effect.

Therefore, depending on whether or not an electric field is applied, the condensing angle of the entire lens changes, and the focal length changes. In other words, light control can be performed by applying an electric field.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 1 shows a variable focal length microlens showing one embodiment of the present invention. In the figure, a flat Fresnel lens 3 is laminated on a substrate 2 to form a flat microlens 1. The substrate 2 is made of an electro-optic effect crystal such as LiN, 03, etc., and electrodes 4.5 are provided on both sides, and a power source 6 is connected to the electrodes 4.5.

In the flat microlens 1 , when parallel light enters the flat Fresnel lens 3 , the flat Fresnel lens 3 collects the parallel light. Now, the electric field from the power source 6 is applied to the electrode 4.
．． It is assumed that the light is focused along the path shown by the solid line when no voltage is applied to 5.

Next, when a voltage is applied to the electrodes 4.5 from, for example, the power source 6, an electric field is applied to the substrate 2, which is an electro-optic effect crystal, and the refractive index changes. Therefore, the light focused by the flat Fresnel lens 3 takes the path shown by the broken line. In this way, the focal length of the flat microlens 1 can be changed by turning on/off the electric field applied to the substrate 2.

As a modified example of this flat plate microlens, a flat Fresnel lens 3 is used, for example 1. If it is formed of a transparent conductive film such as T or O, the flat Fresnel lens 3 can also be used as one electrode for applying an electric field, as shown in FIG. The other electrode 4 is formed of a transparent conductive film and is arranged parallel to the flat Fresnel lens 3 with the substrate 2 having an electro-optic effect sandwiched therebetween. Incidentally, as shown in FIG. 3, an electrode 5 formed of a transparent conductive film may be arranged between the substrate 2 and the flat Fresnel lens 3.

These variable focus lenses using electro-optic effects can be used to construct high-speed optical switches, pickup objective lenses with high-speed focusing functions, etc. if the electro-optic effects are large.

FIG. 4(A) and FIG. 4(B) show a microlens with a deflection function showing another embodiment of the present invention. In the figure, a rectangular parallelepiped substrate portion 12 is formed by bonding two triangular prism-shaped substrates 12a and 12b, and a flat Fresnel lens 13 is adhered to this substrate portion 12 to form a flat microlens 11. . Boards 12a, 12b beams, N
, 03, etc. is used as the material, and electrodes 14a, 15a, 14b, 1 are insulated from each other on the front and back surfaces.
5b, and power supplies 16a and 16b having opposite polarities are connected between the electrodes 14a and 15a, and between the electrodes 14b and 15b.

In the flat microlens 11 , when parallel light enters the flat Fresnel lens 13 , the flat Fresnel lens 13 collects the parallel light. When the electric field from the power supplies 6a and 6b is not applied to the substrates 12a and 12b,
The refractive index of the side substrates 12a and 12b is the same, and the light
The light is focused along the path shown by the solid line in Figure (A). Power supply 6a, 6
When an electric field due to b is applied to the substrates 12a and 12b,
Positive and negative refractive index changes occur in the substrates 12a and 12b, respectively, and a refractive index difference occurs at the interface between the substrates 12a and 12b, so that the light beam focused by the flat Fresnel lens 13 becomes as shown in FIG. 4(A). Deflect as shown by the dashed line. In this way, the flat microlens 11 can deflect the light beam by turning on/off the electric field applied to the substrates 12a and 12b.

FIG. 5 is a diagram showing another microlens with a deflection function. In the figure, a flat microlens 21 is constructed by adhering a flat Fresnel lens 23 to a substrate 22 formed of an acousto-optic effect crystal, and further disposing a crystal oscillator 24 on the side surface of the substrate 22. A high frequency signal source 26 is connected to the crystal resonator 24 .

In this flat plate microlens 21, a crystal oscillator 24
When no signal from the high-frequency signal source 26 is applied to the laser beam, the light beam focused by the flat plate microlens 23 is not deflected and follows the path shown by the solid line in FIG. When a high frequency voltage is applied to the crystal resonator 24 from the high frequency signal source 26,
Ultrasonic diffraction grating 25 in the acoustic optical effect crystal 22
occurs. When the light beam from the flat Fresnel lens 23 is incident on the diffraction grating 25, it is deflected along the path shown by the broken line in FIG. 5 due to the effect of diffraction.

By using the above-mentioned flat plate microlens with a deflection function, it is possible to realize a pink-up objective lens having high-speed tracking ability, a high-speed optical switch, and the like.

FIG. 6 is an explanatory diagram of a polarization separation type high-speed optical switch showing still another embodiment of the present invention. This polarization separation type high-speed optical switch 31 includes a flat Fresnel lens 33 disposed on the front end surface of a substrate 32, a polarization beam splinter 37 disposed on the rear end surface of the substrate 32, and a polarization beam splinter 37 disposed on the rear end surface of the polarization beam subric 37 (jjll end). However, plane Fresnel lens 3
8.39 is arranged, and an input polarization maintaining optical fiber 40 is connected to the front end of the flat Fresnel lens 33, and an output optical fiber 41.42 is connected to the flat Fresnel lens 39. . The substrate 32 is made of an anisotropic optical crystal that exhibits an electro-optic effect, has electrodes 34 and 35 on its sides, and is connected to a power source 36. An anisotropic optical crystal has a refractive index that differs depending on the crystal axis, and a change in the refractive index due to the electro-optic effect also differs depending on the crystal axis. Therefore, the substrate 32 functions as a phase modulation element and further as a polarization plane rotation element. The flat Fresnel lens 33 consists of a Fresnel lens layer 33a and a protective film layer 33b.

The same applies to the other flat Fresnel lenses 38 and 39. The polarizing beam brick 37 is an element that branches the beam depending on the polarization direction of the light.

In this optical switch 31, an electrode 34.
Input optical fiber 40 with no voltage applied to 35
When the input light is incident, it is converted into parallel light by the flat Fresnel lens 33 and passes through the substrate 32 . Since no electric field is applied to the substrate 32, the passing light does not undergo rotation of the plane of polarization, travels straight through the polarization beam brick 37, passes through the flat Fresnel lens 38, and is output from the output optical fiber 41. On the other hand, when a voltage is applied to the power supply 36 and/or electrodes 34 and 35, the polarization direction of the light passing through the substrate 32 is rotated by 90 degrees due to the electric field, and the polarization beam subric 37 rotates the light in the orthogonal direction, that is, the polarization direction of the light passing through the substrate 32 is rotated by 90 degrees. fresnel lens 39
It is output to the output optical fiber 42 through the . in this way,
Power from power supply 36.

By turning the voltage on and off to the poles 34.35, the output light beam can be split and light switching can be effected.

This polarization separation type high-speed optical switch is constructed by combining an anisotropic optical crystal with an electro-optic effect with a polarization beam splinter and a plurality of flat Fresnel lenses with protective films, and can be integrated into a small size. Since the beam diameter can also be reduced, safe high-speed optical switches can be realized.

In addition, in the above-mentioned embodiment, the case where an electro-optic effect and an acousto-optic effect are used is given as an example, but the present invention is not limited to this, and the present invention is not limited to this. It may also be used for a substrate.

(F) Effects of the Invention According to the present invention, the substrate of the flat microlens is made of a material having at least one of an electro-optic effect, an acousto-optic effect, a magneto-optic effect, a thermo-optic effect, and a nonlinear optical effect, Since light control is performed by applying a physical quantity corresponding to the optical effect possessed above, it is not necessary to prepare a special light control element and consider the combination with it. A flat plate microlens having in h capability can be obtained. By using this flat plate microlens, it is possible to construct an optical system that is more compact than the conventional one.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a microlens with a variable focal length showing an embodiment of the present invention, FIGS. 2 and 3 are explanatory diagrams showing a modified example of a microlens with a variable parfocal length, and FIG. (A) is an explanatory diagram of a microlens with a deflection function showing another embodiment of the present invention, and FIG. 4(B) is an explanatory diagram for explaining how to apply an electric field to the microlens with a deflection function. FIG. 5 is a diagram showing another microlens with a deflection function, and FIG. 6 is an explanatory diagram of a polarization separation power high-speed optical spinch showing still another embodiment of the present invention. 2.12a.12b.22.32: Board, 3.13.
23/33: Flat Fresnel lens, 4/5/1
4a 14b 15a 15b: Electrode, 34
・35: Electrode, 6, 16a, 16b, 26, 36: Power supply.

Claims (1)

[Claims] (1) The substrate of the flat microlens is made of a material having at least one of an electro-optic effect, an acousto-optic effect, a magneto-optic effect, a thermo-optic effect, and a nonlinear optical effect, and the substrate is made of a material having at least one of an electro-optic effect, an acousto-optic effect, a magneto-optic effect, a thermo-optic effect, and a nonlinear optical effect, and A flat microlens characterized by having a light control function by applying a physical quantity.