JPS5824111A - Light beam deflection scanner - Google Patents

Abstract

PURPOSE:To reduce influence by a variation of a scanning line, by irradiating a holographic filter having a microscopic opening at a prescribed angle by a parallel coherent light, deflecting the primary diffracted light from said filter by a deflector, and after that, condensing it. CONSTITUTION:Laser light 11 from a laser oscillator 10 is converted to parallel light 13 by a collimator lens system 12, and in an optical path of this parallel light 13, an opening douser 20 having a circular opening 21 is provided. As a result, diffracted light 14 is generated from the opening 21, and this diffracted light 14 is converted to parallel light 16 by a lens system 15 and is irradiated to a photosensitive material. On the other hand, in order to record an amplitude information and a phase information regarding the opening 21 in a photosensitive material 17, laser light 18 which is made incident at an angle theta converted to reference light, simultaneously is irradiated to the photosensitive material 17, an interference fringe is formed by the parallel light and the reference light, a holographic filter 30 corresponding to the opening 21 is formed, such a filter 30 is provided on a light beam deflection scanner, parallel light 31 is irradiated at at the same angle theta as the reference light 18, primary diffracted light 34 is obtained, is deflected 35, and after that, is condensed 36, and a photosensitive material 38 is exposed by a scanning beam 37.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical beam deflection/scanning device in which the edge portion of a scanning light beam is sharp and its intensity distribution is relatively flat.

In a conventional optical beam deflection/scanning device, for example, as shown in FIG. 1, a laser beam 2 from a laser oscillator 1 is converted into parallel light 4 by a collimator lens system 3, then deflected by a deflector 5, and then sent to a condenser lens. The system 6 focuses the light, and the beam 7 scans the photosensitive material 8 and exposes it. As described above, conventional deflection/scanning devices use a coherent laser beam as a light beam, but the laser beam has a so-called Gaussian intensity distribution. For this reason, the intensity distribution of the light beam 70 that exposes the photosensitive material 8 also has a Gaussian distribution curve as shown in FIG. 2, and the edge of the scanning beam becomes less sharp and the width of the scanning line changes depending on the amount of exposure. There are drawbacks such as: Therefore, an object of the present invention is to provide a light beam deflection/scanning device free from such drawbacks, in which the edge portion of the scanning light beam is sharp and its intensity distribution is relatively flat.

This invention will be explained below.

In the present invention, first, a holographic filter is created using coherent light, such as a laser, and the manner of its creation will be explained with reference to FIGS. 3 and 4. That is, the laser beam 11 oscillated from the laser oscillator IO is converted into parallel light 13 by collimating the lens system, and this parallel light 13
An aperture light plate having a circular aperture 4 is disposed in the optical path of the light beam. In this case, the aperture shielding plate is large enough to block the parallel light 13, and the aperture 4 is sufficiently small compared to the diameter of the parallel light 13. As a result, diffracted light 14 is generated from the aperture 21, and this diffracted light 14 is transmitted through the lens system (
7-Lie transform system) 15 as parallel light 16 to light-sensitive material 17
irradiate. Note that the focal length of the lens system 15 is f. On the other hand, in order to record amplitude information and phase information regarding the aperture 21 on the photosensitive material 17, the photosensitive material 17 is simultaneously irradiated with parallel light (laser light) 18 incident at an angle of - as reference light. In this way, interference fringes are formed by simultaneously irradiating the photosensitive material 17 with parallel light giving amplitude information and phase information regarding the aperture 21 and the reference parallel light 18, and a holographic filter field corresponding to the aperture 21 is formed. can be created.

Next, the holographic filter produced as described above is placed in a light beam deflection/scanning device as shown in FIG. That is, the holographic filter (
2), parallel light 31 is irradiated at the same incident angle W# as the angle 0 at which reference light 18 was irradiated when creating this. In this case, the parallel light 31 is formed by the laser oscillator section and the collimator lens system 11 as described above. In this way, when the parallel light 31 is irradiated onto the holographic filter I at an incident angle θ, first-order diffracted light is obtained from the holographic filter I, so this diffracted light is deflected by a deflector and then condensed. A lens system (inverse Fourier transform system) condenses light to form a scanning light beam r, and this light beam n sensitizes between photosensitive materials. Here, since the amplitude information and phase information regarding the aperture 21 are recorded in the holographic filter, the aperture 21 is reproduced in the light beam 37 formed by condensing the first-order diffracted light. The cross-sectional shape of the light beam γ becomes circular corresponding to the aperture 4, and its intensity distribution is flattened as shown in FIG. In other words,
, the intensity of the edge portion can be sharpened, and the above-mentioned drawback of changing the scanning line width can be eliminated.

In addition, although the shape of the opening was explained as circular in the above-mentioned embodiment, it can be any shape such as a square or a triangle.
In this case, the cross-sectional shape of the light beam also has a shape corresponding to this. Further, the light beam not only sensitizes the photosensitive material, but can also be read by an optical system and used separately. Furthermore, a holographic filter can also be created using a computer.

As described above, according to the optical beam deflection/scanning device of the present invention, the edge portion of the scanning dog beam is sharpened and its intensity distribution is flattened, so that the influence of variations and fluctuations in the scanning line is reduced. can do. In addition, since the scanning light beam can be formed with a cross-sectional shape corresponding to the shape of the aperture used to create the holographic filter, its application fields are wide.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a conventional deflection/scanning device using a light beam, Fig. 2 is a diagram showing the intensity distribution of the light beam, and Fig. 3 is a diagram showing a method for creating a holographic filter used in the present invention. FIG. 4 is a plan view showing an example of an aperture light shielding plate used for creating a holographic filter,
FIG. 5 is a diagram showing a schematic configuration example of the light beam deflection/scanning device of the present invention, and FIG. 6 is a diagram showing the intensity distribution of the light beam of the present invention. 1.10.32...Laser oscillator, 3,12.33.
... Collimator lens system, 5.35 ... Deflector, 6.
A...Condensing lens system, 8,17.38...Photosensitive material, Addition...Aperture light shielding plate, 21...Aperture, Addition...Holographic filter, a...Light beam.

Claims (1)

[Claims] A holographic filter having a minute aperture is irradiated with parallel coherent light at a predetermined angle, and the first-order diffracted light from the holographic filter is deflected by a deflector and then condensed by a condensing lens system, thereby forming an edge part. 1. A light beam deflection/scanning device characterized in that a light beam can be scanned over a scanning surface with a light beam having a sharp intensity distribution and a relatively flat intensity distribution.