JPH08220464A - Optical scanner - Google Patents

Abstract

PURPOSE: To provide an optical scanner where a large deflection angle is obtained and which has a large number of resolution points. CONSTITUTION: This device is constituted of a light transmissive substrate 1, plural waveguides 2 formed on the surface of a substrate and having an electrooptic effect and film thickness equivalent to a cut-off film thickness and an electrode 4 disposed so as to impress voltage to the waveguide, and possesses plural cut-off switches arrayed in an array state and a controlling means controlling the voltage impressed to each electrode, and controls waveguide light advancing in the wave guide by impressing desired voltage to each electrode and deflecting light in a digital system so that desired light output is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device, and more particularly to an optical scanning device used in laser printers, digital copying machines, laser displays and the like.

[0002]

2. Description of the Related Art Conventionally, a device for scanning light (optical deflector)
Known polygon mirrors, galvano mirrors, and the like. These are now widely spread and applied to laser printers and the like. In such a mechanically controlled optical deflector, the natural rotation speed of the vibrating element is about 2.5 kHz, and if the polygon mirror is an octahedron, the deflection speed is several tens kHz. However, stable operation is possible in a wide angle, high speed is achieved by using a divided laser beam, and 256 gradations are realized by electrical control.

Under such circumstances, electro-optical control and acousto-optical control are considered for further speeding up, but they are also shown in laser engineering (co-authored by Takashi Azagami et al., Ohmsha) at present. As described above, in particular, the deflection speed of the optical deflector under the electro-optical control and the acousto-optical control can be higher than the mechanical control in principle.

In addition, an acousto-optical light deflector is several 100M.
While the deflection speed of Hz can be obtained, the electro-optical optical deflector is expected to have the highest deflection speed of several tens GHz. Therefore, the electro-optical light deflector is most promising when increasing the deflection speed. By the way, since an optical switch based on electro-optical control can operate at high speed in principle, research on an optical switch for communication and an optical switch for information processing has been actively conducted. Such optical switches include directional couplers, Mach-Cender interferometers, and total internal reflection (TI).
R) switch, cut-off switch, etc.

[0005]

However, the electro-optical light deflector has a small deflection angle, and the number of resolution points (a value obtained by dividing the deflection angle by the beam spread) indicating the performance of the light deflector is several points. There is a problem of being small. Further, light deflection by electro-optical control requires a high voltage.

[0006] Among these problems, with respect to the drive voltage, a technique for suppressing the drive voltage to a low level by forming a waveguide has been proposed and can be solved. However, the problem that the deflection angle is small and the number of resolution points is small has not been approved yet.

The present invention has been made in view of the above circumstances, and an object thereof is to provide an optical scanning device which can obtain a large deflection angle and has a large number of resolution points.

[0008]

According to the present invention, a waveguide having a film thickness corresponding to a cut-off film thickness is formed on a transparent substrate surface, and electrodes are arranged in an array to cut the array. An off-switch is formed and a desired voltage is applied to the electrodes to deflect light in a digital manner, thereby forming an optical scanning device having a number of resolution points corresponding to each dot.

That is, the first feature of the present invention is that a transparent substrate and a plurality of waveguides having an electro-optical effect formed on the surface of the substrate and having a film thickness corresponding to a cut-off film thickness. A cutoff switch composed of an electrode arranged to apply a voltage to the waveguide, arranged in an array, and a control means for controlling the voltage applied to each electrode, By applying a desired voltage to each of the electrodes, the light is digitally deflected, the guided light traveling through the waveguide is controlled, and a desired light output is obtained.

A second feature of the present invention is that a transparent substrate is provided,
Arrays each having a pair of waveguides formed on the surface of the substrate and having a film thickness corresponding to the cutoff film, and an insulating thin film formed so as to cover the surface of the waveguides so as to sandwich the waveguides. An array-shaped cutoff switch group composed of a plurality of pairs of electrodes arranged in a row, and a control means for controlling the voltage applied to each electrode, and applying a desired voltage to each electrode. Thus, the light is digitally deflected and the guided light traveling through the waveguide is controlled to obtain a desired light output.

A third feature of the present invention is that a transparent substrate is provided,
A transparent first electrode group formed on the surface of the substrate, a first insulating thin film formed on the first electrode group, and a cut formed on the first insulating thin film. A waveguide having a film thickness corresponding to the off film thickness, a second insulating thin film formed so as to cover the surface of the waveguide, and a second electrode formed on the second insulating thin film. Group and a control means for controlling a voltage applied between the first electrode group and the corresponding second electrode group, and a desired voltage between the first and second electrode groups. Is applied, the light is digitally deflected, the guided light traveling through the waveguide sandwiched by the corresponding electrode pairs of the first and second electrode groups is controlled, and a desired light output is obtained. There is something I did.

A fourth feature of the present invention is that the branch waveguide is branched into a number corresponding to the number of scanning points, and the pair of electrodes are arranged so as to apply a voltage to each of the branch waveguides. It has a plurality of cut-off switches.

Desirably, a reflecting means having a tapered reflecting surface is provided on a part of the translucent substrate, and the light is extracted in a direction forming a predetermined angle with respect to the light propagating direction. .

More preferably, the light is extracted in a direction perpendicular to the light propagation direction.

Preferably, the control means is configured to adjust the light intensity of the light output to obtain gradation.

[0016]

The cutoff phenomenon adopted in the cutoff switch is that, as shown in FIG. 1, when the film thickness of the waveguide 2 is reduced, light is no longer guided and is emitted to the substrate 1 side. It is a phenomenon. At this time, the film thickness (cutoff film thickness) of the waveguide is determined by the refractive indices of the substrate, the waveguide, and the air layer. A cut-off switch is an application of this phenomenon to a switch. In this cut-off switch, as shown in FIG. 2, for example, a channel type waveguide formed on a lithium niobate (LiNbO ₃ ) substrate 1 as an electro-optic crystal has a cut-off film thickness. Here, the light source is a semiconductor laser, an LED, or the like. When no voltage is applied to this electrode, the guided light is cut off and emitted from the waveguide to the substrate side. On the other hand, when a voltage is applied, the refractive index changes, the cutoff film thickness increases, and the cutoff is not achieved. The cut-off switch utilizes this phenomenon to separate light. According to the literature, it is possible to almost completely separate the inside and outside of the waveguide with a potential difference of about 30V.

When cut off, the angle θ formed by the emitted light and the traveling direction of the light is about 15 degrees (PK Tie).
n and R. J. Martin Appl. Phy
s. Lett. 18, 9, 398 (1971)).

In the first aspect of the present invention, by arranging the cut-off switches in an array and deflecting light in a digital manner, it can be used as an optical scanning device having a resolution point number corresponding to each dot. That is, as shown in FIG. 3, when a voltage is applied to each electrode 4, guided light is emitted to the substrate side.

In the second aspect of the present invention, a pair of electrodes are formed on the waveguide surface via an insulating film and a voltage is applied in parallel to the substrate surface. Therefore, the structure is simple and the number of manufacturing steps is small. It is possible to provide an optical scanning device having a small number and a large number of resolution points. Further, in this structure, the voltage is applied in the direction parallel to the substrate surface, and the cutoff depends on the film thickness of the waveguide, so that the effect of high controllability is achieved.

Further, in the third aspect of the present invention, since the voltage is applied in the direction perpendicular to the substrate surface, the cutoff depends on the film thickness of the waveguide.

However, as is clear from FIG.
At an emission angle of about 5 degrees, the light can be emitted only from the same plane as the emission surface of the guided light, and the distance between resolution points corresponds to each dot, that is, tan15 degrees = 0.2679 times the distance between electrodes, and minute dots are created. However, since the scanning range is limited to the thickness of the substrate, the size of the apparatus becomes large.

Therefore, it is desirable that a part of the translucent substrate be provided with a reflecting means having a tapered reflecting surface so that the light is extracted in a direction forming a predetermined angle with respect to the light propagating direction. By doing so, the scanning width can be increased.

More preferably, the light is extracted in a direction perpendicular to the light propagation direction. With this configuration, light can be extracted from the side surface of the substrate, and it is possible to perform optical scanning over a wide range with a small device. (A scanning range corresponding to the length of the crystal substrate on which light travels is possible.) Furthermore, according to the fourth aspect of the present invention, a branching waveguide branched into a number corresponding to the number of scanning points is provided. Since a pair of electrodes is arranged so as to apply a voltage to the branch waveguides, the number of resolution points can be reliably obtained.

Desirably, if the control means is constructed so as to adjust the light intensity of the light output to obtain gradation, it is possible to easily obtain a high resolution output having gradation.

As described above, according to the present invention, it is possible to provide a small-sized optical scanning device having a large scanning width and capable of high-speed operation.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 4 is a diagram showing an optical scanning device according to an embodiment of the present invention, and FIGS. 5 (a) and 5 (b) are sectional views thereof. Figure 5
5A is a sectional view taken along the line AA of FIG. 4, and FIG. 5B is a sectional view taken along the line BB of FIG. This optical scanning device uses a LiNbO ₃ substrate 1 which is a translucent electro-optic crystal as a substrate and is formed by diffusing titanium on this surface by a thermal diffusion method, which is slightly thicker than the cutoff film thickness and has a width of 3 μm. A channel waveguide 2 made of a titanium diffusion layer, a buffer layer 3 made of a glass material called Corning 7059 (hereinafter referred to as a glass material) and having a thickness of 100 nm formed on the surface of the channel waveguide 2. On the surface of the buffer layer 3, a large number of pairs of gold electrodes 4 arranged in array on both sides along the waveguide.
(4a, 4b) and the laser light propagating through the waveguide 2 are inclined at an angle of 10 to 70 degrees (an angle calculated from the refractive index of the material and the wavelength of the incident beam) with LiNbO ₃
The reflection film 5 is formed of an aluminum layer that covers the tapered surface formed on the back surface of the substrate 1. In front of the waveguide 2, a light source 100 made of a semiconductor laser is provided.
And an optical system such as a collimator lens 200 for collimating the light from the light source, and the light is incident on the waveguide 2. Here, the buffer layer is provided to prevent transmission loss.

In this apparatus, when no voltage is applied to the gold electrode 4, the laser light incident on the LiNbO ₃ substrate 1 proceeds through the waveguide 2 as it is.

On the other hand, when a predetermined voltage V0 is applied to the gold electrodes 4 (4a, 4b), the light is cut off and emitted to the substrate side, reflected by the reflection film 5 and perpendicular to the traveling direction of the laser light. It is output so as to penetrate the surface, that is, the A surface. When the voltage is applied in this way, it is turned on, and printing is performed by the output light.

Next, a second embodiment of the present invention will be described. FIG. 6 is a diagram showing an optical scanning device according to an embodiment of the present invention, and FIG. 7 is a sectional view thereof. This optical scanning device uses a slab type waveguide, and is made of indium tin oxide (IT) formed on the surface of a transparent glass substrate 11 made of a glass material.
O) layer which is a translucent first electrode 14, a buffer layer 15 which is formed on the upper layer and is made of a glass material thin film having a thickness of 100 nm, and a C-axis oriented ZnO layer which is formed on the upper layer.
A waveguide 16 made of a thin film, and a buffer layer 1 made of a glass material thin film having a film thickness of 100 nm and further formed on the waveguide 16.
7, a second electrode 18 made of an aluminum layer formed on the buffer layer 17, and a reflecting mirror 19 made of an aluminum film formed on the taper surface of the back surface of the substrate. Further, in front of the waveguide 16, a light source 100 made of a semiconductor laser and an optical system such as a collimating lens 200 for collimating the light from the light source are arranged so as to enter the waveguide 16. There is.

Next, a method of manufacturing this optical scanning device will be described. First, a glass material is used as a substrate, an ITO thin film is formed on this surface by a sputtering method, and patterned by a photolithography method to form the first electrode 14.

Next, a glass material thin film is formed on this upper layer by a sputtering method to form a buffer layer 15, and a Zn film having a predetermined film thickness is further formed by the sputtering method.
After forming an O thin film, annealing is performed using a CO ₂ laser to form a waveguide 16 composed of a C-axis oriented ZnO thin film 16.
To form. The thickness of this ZnO thin film is equal to that of the glass material and Z.
The cut-off film thickness t _c determined from the refractive index of nO and the light source used.

After that, a glass material thin film is formed on the upper layer again by the sputtering method and patterned by photolithography to obtain the buffer layer 17.
Then, an aluminum layer is further formed by a vapor deposition method, and an electrode pattern is formed by photolithography to obtain the second electrode 18. Then, the taper angle of the back surface of the substrate is determined based on the radiation angle calculated from the refractive index of the material used, and cutting and polishing are performed based on this angle.

Finally, a reflecting mirror 19 made of a metal thin film such as aluminum is vapor-deposited on this cut surface, and the reflection mirror 19 shown in FIGS.
The optical scanning device shown in FIG. Next, the operating principle of this optical scanning device will be described. As shown in FIG. 7, the light emitted from the light source 100 enters the waveguide through the collimator lens 200. And the buffer layer 15,
If no voltage is applied between the first electrode 14 and the second electrode 18 via 17, the light travels in the waveguide as it is,
It proceeds in the direction of arrow P as it is. On the other hand, when a voltage is applied, the light is cut off, passes through the first electrode 14, and is emitted to the substrate side. The radiated light is reflected by the reflecting mirror 19 on the back surface, reaches the surface, and is emitted from the surface A in the direction of arrow Q.

By thus disposing the photosensitive drum behind the surface A, printing is performed and the number of resolution points increases corresponding to the electrode disposition density.

Next, as a third embodiment of the present invention, an optical scanning device using a branch type waveguide will be described. Figure 8
FIG. 9 is a diagram showing an optical scanning device of an embodiment of the present invention, and FIG. 9 is a sectional view thereof. This optical scanning device uses a branched waveguide, and has a film thickness t formed of an MNA thin film (2 methyl 4 nitroaniline) having an EO effect, which is formed on the surface of a transparent substrate 11 made of a glass material. Crystal thin film branch type waveguide 26 of _c
An insulating thin film 25 made of a glass material and having a film thickness of 100 nm formed on the crystal thin film branching waveguide 26, and an upper layer formed so as to surround a predetermined region of the crystal thin film branching waveguide 26. It is composed of a pair of gold electrodes 24, and a light absorbing thin film 2 such as aluminum is formed on the end face of the substrate 11.
It is characterized in that a reflecting mirror 30 made of a gold thin film is formed via 9 And a light source 100 composed of a semiconductor laser
And an optical system such as a collimator lens 200 for collimating the light from the light source, and the light is incident on the waveguide 26.

Next, a method of manufacturing this optical scanning device will be described. First, a glass material is used as a substrate, an MNA thin film is grown on this surface from a melt, and patterned by a photolithography method to form a branched waveguide 26. This MNA thin film is formed by a melt method or a vapor phase method. The film thickness t _c of this MNA film is a cut-off film thickness t _c determined from the refractive index of the glass material and MNA with respect to the light source used.

Next, an insulating thin film 25 made of a glass material is formed on the upper layer by a sputtering method, a gold layer is further formed by a vapor deposition method, and an electrode pattern is formed by photolithography to obtain a gold electrode 24. Finally, a light absorbing thin film 2 such as colored glass is used as a medium for absorbing laser light on a portion of the light emitting surface other than the waveguide.
And a reflecting mirror 30 formed of a gold thin film.
And the optical scanning device shown in FIGS. 8 and 9 is formed. Next, the operating principle of this optical scanning device will be described. As shown in FIG. 9, the light emitted from the light source 100 enters the waveguide via the collimator lens 200.
Then, this guided light is branched into four channels by the branch type waveguide. This channel corresponds to the number of dots.

When a voltage is applied to the gold electrode 24, the light is cut off and emitted to the substrate side. Since the light absorbing thin film 29 and the reflecting mirror 30 made of a gold thin film are formed here, the emitted light is blocked without going out. On the other hand, if no voltage is applied, the light is emitted as it is. In this way, in this optical scanning device, the output is turned off when a voltage is applied, and printing is not performed.

By thus disposing the photosensitive drum behind the surface A, printing is performed, and the number of resolution points can be increased corresponding to the density of the branch paths.

[0040]

As described above, according to the present invention, it is possible to provide a high-speed, high-reliability optical scanning device capable of driving at a low voltage and having high reliability.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of an optical scanning device according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the principle of the optical scanning device according to the embodiment of the present invention.

FIG. 3 is an explanatory view of the principle of the optical scanning device according to the embodiment of the present invention.

FIG. 4 is a diagram showing an optical scanning device according to a first embodiment of the present invention.

FIG. 5 is a sectional view of the optical scanning device.

FIG. 6 is a diagram showing an optical scanning device according to a second embodiment of the present invention.

FIG. 7 is a sectional view of the optical scanning device.

FIG. 8 is a diagram showing an optical scanning device according to a third embodiment of the present invention.

FIG. 9 is a sectional view of the optical scanning device.

[Explanation of symbols]

1 LiNbO ₃ Substrate 2 Channel Waveguide 3 Buffer Layer 4 Gold Electrode 5 Reflective Film 11 Glass Substrate 14 Translucent First Electrode 15 Buffer Layer 16 Waveguide 17 Buffer Layer 18 Second Electrode 18 19 Reflector 100 Light Source 200 Collimating lens

Claims (6)

[Claims] 1. A transparent substrate, a waveguide having an electro-optical effect formed on the surface of the substrate, having a film thickness corresponding to a cut-off film thickness, and applying a voltage to the waveguide. A plurality of cut-off switches, each of which has a plurality of electrodes arranged in an array, and control means for controlling a voltage applied to each of the electrodes, and applying a desired voltage to each of the electrodes. The optical scanning device is characterized by digitally deflecting light to control guided light traveling in the waveguide to obtain a desired optical output. 2. A transparent substrate, a waveguide formed on the surface of the substrate and having a film thickness corresponding to a cut-off film thickness, and an insulating thin film formed so as to cover the surface of the waveguide. An array-shaped cut-off switch group including a plurality of pairs of electrodes arranged in an array so as to sandwich the waveguide along the waveguide, and a voltage applied to each electrode is controlled. A control means, by applying a desired voltage to each of the electrodes, the light is digitally deflected, and the guided light traveling through the waveguide is controlled to obtain a desired light output. The optical scanning device according to claim 1, wherein: 3. A transparent substrate, a transparent first electrode group formed on the surface of the substrate, a first insulating thin film formed on the first electrode group, A waveguide formed on the first insulating thin film and having a film thickness corresponding to a cutoff film thickness, a second insulating thin film formed so as to cover the surface of the waveguide, and the second insulating film. A second electrode group formed on the conductive thin film, and control means for controlling a voltage applied between the first electrode group and the corresponding second electrode group, the first and By applying a desired voltage between the second electrode group, the light is digitally deflected, and the light is guided through the waveguide sandwiched by the corresponding electrode pair of the first and second electrode groups. The optical scanning device according to claim 1, wherein the wave light is controlled to obtain a desired light output. 4. A light-transmitting substrate, a branch conductor having an electro-optical effect formed on the substrate surface, having a film thickness corresponding to a cut-off film thickness, and being branched into a number corresponding to the number of scanning points. A plurality of cutoff switches each including a waveguide and electrodes arranged in pairs so as to apply a voltage to each of the branch waveguides; and a control unit for controlling the voltage applied to each of the electrodes. By applying a desired voltage to each of the electrodes, the light is digitally deflected, the guided light traveling through the waveguide is controlled, and a desired light output is obtained. The optical scanning device according to claim 1. 5. The light transmissive substrate is provided with a reflection means having a tapered reflection surface on a part thereof, and the light is extracted in a direction forming a predetermined angle with respect to a light propagation direction. The optical scanning device according to any one of claims 1 to 4, wherein: 6. The optical scanning device according to claim 1, wherein the control unit is configured to adjust the light intensity of the light output to obtain gradation.