JPS6348519A - Optical scanning device - Google Patents

Abstract

PURPOSE:To scan luminous flux on a specific surface with a specific light intensity distribution by moving the luminous flux guided out of a guiding-out means and also controlling the intensity of luminous flux incident on a medium by a light control part according th the medium of a local elastic wave area which is caused in the medium by an elastic wave generating means. CONSTITUTION:When an elastic wave is generated by the elastic wave generating means 3 powered on by a power source 6, an area of optical anisotropy is formed speedily in the medium 4 and moves in the medium 4. Linear polarized light incident on the medium 4 is phase-modulated partially corresponding to a slit area according to the movement of the area of optical anisotropy to become elliptic polarized light. Consequently, luminous flux with intensity corresponding to the ellipticity of the elliptic polarized light is projected from an area on the polarizing plate 5 corresponding to the area of optical anisotropy is projected so as to scan on the polarizing plate 5 from different area on the polarizing plate 5. The intensity of this luminous flux is controlled by varying the output value of a light source 1 relatively to the movement of the luminous flux. Consequently, the luminous flux with specific light intensity can be scanned on the specific surface.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an optical scanning device, and in particular to an optical scanning device that uses a medium that produces a photoelastic effect due to an elastic wave to optically modulate a light beam incident on the medium to perform optical scanning. The present invention relates to an optical scanning device suitable for, for example, scanningly illuminating an irradiated surface by utilizing a light beam emitted or reflected from a medium.

(Prior art) Conventionally, in the illumination system of a copying machine or a device that sequentially receives light using a line sensor, a light beam from a light source is guided onto a predetermined surface by mechanical means, and the light beam scans the predetermined surface. ing.

For example, scanning is performed by rotating a polygon mirror and using the reflected light beam from the polygon mirror.

Generally, with mechanical methods, it is difficult to increase the scanning speed, and the mechanism tends to be complicated.

In contrast, various methods have been proposed in which a predetermined surface is scanned with a beam of light using electrical means.

For example, there is a method in which a plurality of liquid crystals are arranged in a line, a voltage is sequentially applied to the liquid crystals, and the birefringence of the liquid crystals is changed to optically modulate the light flux emitted from the liquid crystals.

However, methods using liquid crystals tend to require a large number of drive electrodes and drive circuits to drive each liquid crystal array, making the entire device complicated.

In addition, the response speed of the liquid crystal is not very fast, making it difficult to perform high-speed scanning.Furthermore, the characteristics tend to change due to changes in temperature, etc., and it is very difficult to scan a given surface with a given light intensity distribution. was there.

(Problems to be solved by the invention) The present invention has fast response speed, stable characteristics against environmental changes, can scan a predetermined surface with a predetermined light intensity distribution, and is capable of scanning a predetermined surface with a predetermined light intensity distribution. An object of the present invention is to provide an optical scanning device with a simple configuration using electrical means capable of high-speed scanning.

(Means for Solving the Problems) A medium that produces a photoelastic effect using elastic waves, an elastic wave generating means that applies local elastic waves to the medium, and an input means that makes a light beam having polarization characteristics enter the medium. a deriving means for deriving a luminous flux of a predetermined polarization component out of the luminous flux that has passed through or reflected from the medium, and a local elastic wave region generated in the medium by the elastic wave generating means in the medium; In accordance with the movement of the medium, the light flux led out from the light emitting means is moved, and the light intensity of the light flux incident on the medium is controlled by a light control section.

(Embodiment) FIG. 1 is a schematic diagram of an optical system according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a light source, for example, a surface light source that emits natural light over a wide area, or a light source that has a diffusion optical system inside and emits natural light of uniform intensity over a wide area. 2.5 are polarizing plates, which are arranged so that their polarization axes are orthogonal to each other in a crossed Nicol relationship. 3
The elastic wave generating means is made of, for example, quartz crystal, PZT, an ultrasonic wave generating device, etc. Reference numeral 4 denotes a medium in which optical anisotropy occurs internally due to elastic waves, a so-called photoelastic effect, and is made of, for example, glass or plastic. An elastic wave generating means 3 is fixed to a part of the medium 4. A power source 6 drives the elastic wave generating means 3. Reference numeral 7 denotes a light control section, which controls the light intensity of the light beam emitted from the light source 1 in relation to the voltage applied to the elastic wave generating means 3 from the power source 6.

In this example, the light source! , the polarizing plate 2 and the light control unit 7 constitute a part of the input means.

In the non-embodiment, the elastic wave generating means 3 is activated by applying an alternating current or pulse voltage to the elastic wave generating means 3 from the power source 6.
generates elastic waves.

The elastic waves are then propagated into the medium 4. At this time, optical anisotropy occurs inside the medium 4 due to the photoelastic effect. For example, optical anisotropy occurs in the in-plane direction of the medium 4, the magnitude of which depends on the magnitude of strain. At this time, since the propagation speed of the elastic wave propagating in the medium 4 is high, optical anisotropy occurs quickly. Further, the state in which optical anisotropy occurs at this time is not completely affected by B'-'El due to changes in ambient temperature, etc.

As the elastic wave region propagates in the medium 4, the medium 4
The regions of optical anisotropy that have arisen in the image begin to move at the same time. At this time, for example, if the voltage applied to the elastic wave generating means 3 is made into a pulsed or sinusoidal burst shape for a certain period of time, the optical anisotropy region in the medium 4 becomes a limited and localized region. It begins to move within the medium 4. For example, as shown in FIG. 2, it moves within the medium 4 while having a slit-shaped area 21.

On the other hand, the light beam emitted from the light source 1 passes through a polarizing plate 2 serving as an input means, and is made to enter the medium 4 as linearly polarized light polarized in a predetermined direction. Since the medium 4 can be regarded as optically isotropic when no elastic waves are propagating therein, the linearly polarized light enters the polarizing plate 5 without changing its polarization state. Since the two polarizing plates 2.5 are in an orthogonal Nicols relationship with each other, no light beam is emitted from the polarizing plate 5 serving as a deriving means.

That is, the luminous flux is blocked.

Next, when the power source 6 causes the elastic wave generating means 3 to generate an elastic wave, an optically anisotropic region is quickly generated in the medium 4 as described above, and this region moves in the medium 4. become. Therefore, as the optically anisotropic region in the medium 4 moves, the linearly polarized light incident on the medium 4 undergoes partial sequential phase modulation corresponding to, for example, the slit-shaped region 21 in FIG. 2, that is, the polarization state changes. For example, it becomes elliptically polarized light. Therefore, a light beam with an intensity corresponding to the ellipticity of the elliptically polarized light is emitted from a region of the medium 4 on the polarizing plate 5 corresponding to the optically anisotropic region. That is, the luminous flux is sequentially transmitted from different areas on the polarizing plate 5,
The light is emitted so as to scan the polarizing plate 5. In this embodiment, the light intensity of the light beam emitted at this time is controlled by changing the output value of the light source 1 by the light control section 7 in relation to the movement of the light beam. For example, when the X-axis is taken in the direction of the temple of the elastic wave in the medium 4 shown in FIG. 1, the light intensity of the light beam emerging from the polarizing plate 5 is controlled so that it has a rectangular shape as shown in FIG. 3. There is.

That is, by intermittently turning on and off the light beam from the light source 1, or mechanically or electrically blocking it, it is possible to perform scanning by changing the light intensity into a rectangular shape. In this embodiment, the light beam emerging from the polarizing plate 5 is guided, for example, onto the irradiated surface, and the irradiated surface is intermittently scanned.

FIG. 4 is a schematic diagram of another embodiment of the present invention.

In this embodiment, compared to the embodiment shown in FIG. 1, for example, PLZT
A light intensity modulating section 8 and a polarizing plate 9 made of a material such as 9/65/35 are newly provided between the polarizing plate 2 and the medium 4.

In this embodiment, instead of controlling the output value of the light source 1 by the light control section 7 in the embodiment shown in FIG. The light flux from 1 is incident on the medium 4 and the light is blocked electrically.

For example, the light intensity is modulated based on the signal from the light control unit 7 so that the polarization axes of the polarizing plate 2 and the polarizing plate 9 are in a crossed Nicols state where they are orthogonal to each other or a parallel Nicols state where they are parallel to each other. By changing the birefringence of the portion 8, the intensity of the light beam passing through the polarizing plate 9 is controlled.

As described above, in this embodiment, by optically modulating the light beam from the light source 1 by electrical means, it is possible to make the light beam incident on the medium 4 and to block it at high speed.

The movement of the light beam on the polarizing plate 5 in the example hζ is the same as in the example shown in FIG.

As described above, in this embodiment, the power supply 6 is controlled, the elastic wave generating means 3 generates an elastic wave, and the elastic wave is propagated in the medium 4, thereby moving the optical anisotropy region generated in the medium. The light control unit 7 controls the light intensity of the light beam incident on the medium 4, so that any output distribution such as a rectangular shape or a triangular shape can be obtained. As a result, an optical scanning device is achieved in which the movement of the light flux emitted from the polarizing plate 5 serving as the derivation means and the light intensity of the light flux are arbitrarily controlled.

In the embodiments shown in FIGS. 1 and 4, the case is shown in which the light flux passing through the medium 4 is controlled, but the light flux reflected by the medium 4 may also be controlled.

At this time, the reflected light flux from the medium 4 may be the light flux reflected from the surface of the medium 4, or a reflective film may be applied to the back surface of the medium 4, and the light flux reflected from this reflective surface may be used. .

Instead of arranging the two polarizing plates in a crossed Nicol state in this embodiment, they may be arranged in a parallel Nicol state. At this time, the light/dark relationship in the scanning state of the light flux is simply reversed, and the situation is basically exactly the same.

In this embodiment, in order to prevent the elastic waves propagating in the medium from being reflected at the ends of the medium and going backwards and imparting an adverse B2 qz to the passing light flux, an elastic wave absorbing member is provided at the end of the medium, or an elastic wave absorbing member is provided at the end of the medium. It is preferable that the end portion be configured in a shape such as a triangular shape such that an elastic wave is emitted from the end portion of the medium.

(Effects of the Invention) As described above, according to the present invention, high-speed scanning is possible, and a beam of light is scanned at a predetermined light intensity on a predetermined surface using an electric means that has stable characteristics even against changes in ambient temperature. It is possible to achieve an optical scanning device that can perform the following functions.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical system according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a portion of FIG. 1. FIG. 3 is an explanatory diagram of the light intensity distribution according to f# due to the movement of the luminous flux obtained from the embodiment of FIG. 1, and FIG. 4 is a schematic diagram of another embodiment of the present invention. In the figure, 1 is a light source, 2, 5, and 9 are polarizing plates, 3 is a jlIl wave generating main wave generating means medium, 6 is a power source, 7 is a light control section, and 8 is one light intensity dust part. Patent applicant Yukio Takanashi, representative of Canon Co., Ltd. 1.
11..1 1st Diagram 2 B

Claims (1)

[Claims] A medium that produces a photoelastic effect due to elastic waves, an elastic wave generating means that applies local elastic waves to the medium, an input means that makes a light beam having polarization characteristics enter the medium, and a light beam that has passed through or reflected from the medium. a deriving means for deriving a luminous flux of a predetermined polarized light component, and the light beam is derived from the deriving means as a local elastic wave region generated in the medium by the elastic wave generating means moves in the medium. What is claimed is: 1. An optical scanning device, characterized in that a light beam is moved along the medium, and a light intensity of the light beam incident on the medium is controlled by a light control section.