JPS6353526B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When recording information on a recording medium by deflecting a light beam two-dimensionally, the present invention prevents multiple reflections from occurring in the relay lens used in the deflection system into the recorded information. This invention relates to an optical system for deflecting a light beam that prevents information from being mixed in the form of ghost images or interference fringes and deteriorating the quality of information.

Various methods are possible for recording information by deflecting a light beam, but the influence of multiple reflected light from an optical system seems to be most noticeable when recording in the form of an image.

An example of a conventional configuration of an apparatus for recording an image using a light beam is shown in FIG. In the configuration shown in the first diagram, the laser beam 9 from the laser oscillator 1 is
In a light modulator, e.g. an ultrasonic light modulator, 2,
It is intensity modulated in accordance with an input signal, for example an image signal 8 from a television camera, resulting in a modulated light beam 10. Next, the modulated light beam 10 is deflected in the left-right direction by a first optical deflector, such as a rotating polygon mirror 3, to become a deflected light beam 11, and the deflected light beam 12 passing through the relay lens system 4 becomes a second light beam. It is deflected in the vertical direction by a deflector, such as a galvanometer 5, resulting in a polarized light beam 13 that is deflected two-dimensionally in left and right and up and down directions.

This deflected light beam 13 becomes an imaging light beam 14 through an imaging optical system 6, and forms a raster on a recording medium, for example, a 16 mm color film 7.

The above-mentioned relay lens system 4 optically connects the first optical deflector 3 and the second optical deflector 5, and generally the first and second optical deflectors 3 and 5 are connected to the object point and the second optical deflector 5, respectively. Configure it so that it has a relationship with the image point.
Therefore, if one optical deflector has a two-dimensional deflection function, the relay lens system 4
becomes unnecessary. However, to date, such a two-dimensional optical deflector that is high-speed and high-performance enough to be applied to image recording has not been realized, and the use of the relay lens system 4 has traditionally been an indispensable condition. There is. However, as described in detail below, such an essential relay lens system has a problem in that the quality of the image to be recorded deteriorates due to multiple reflected light generated inside the system.

The manner in which the above-mentioned multiple reflected light is generated will be explained below.

FIG. 2 shows how multiple reflected light is generated by the lens immediately after the first optical deflector 3 in the configuration shown in FIG. The light beam 11 exiting the first optical deflector 3 is deflected in a direction perpendicular to the plane of the paper, and the lens 1
5, the light is focused onto a condensing surface 20 that is conjugate with respect to the recording medium 7 shown in the first diagram. As a result, multiple reflected light 19 is generated as shown in the figure. The figure shows only the one with the largest energy among the multiple reflected lights, but countless other reflected lights are also generated. The manner in which the multiple reflected light 19 is generated differs depending on the type of lens used. In a lens with a large number of lenses, such as a normal photographic lens, the shape of the multiple reflected light 19 becomes complex, and the shape of the multiple reflected light 19 becomes complicated. The shape of the multiple reflected light 19 generated in a relay lens system that combines multiple lenses becomes even more complex.

Among the multiple reflected lights mentioned above, those far away from the optical axis have little effect on the recorded image, but those very close to the optical axis interfere with the main beam and cause so-called fringes on the recorded image. let

In any case, in the configuration shown in FIG. The noise becomes a noise whose intensity is distributed in the horizontal direction of the original deflection, and even after passing through the second optical deflector 5 and being deflected in the direction perpendicular to the one-dimensional deflection, the pattern of intensity distribution for each one-dimensional deflection remains unchanged. Noise with the same intensity distribution continues vertically, creating ghost images with vertical stripes, etc.
becomes noticeably noticeable.

On the other hand, the multiple reflected light generated in the optical system after passing through the second optical deflector 5 rarely overlaps with the main beam in areas other than the center, and rarely causes interference. Becomes a point,
The peripheral area becomes interference fringes with a two-dimensional distribution of strength and weakness in the recorded image, similar to the so-called Newton rings that occur concentrically due to the mutual interference of multiple reflected lights between the reflecting plane and the reflecting spherical surface. Since the degree of interference is weak, it is much less noticeable than the above-mentioned vertical striped ghost image and does not pose a particular problem.

Therefore, if the multiple reflected light generated in the optical system after the first optical deflector 3 and before the second optical deflector 5 can be removed, the quality of recorded images can be significantly improved.

In order to remove such multiple reflected light from optical elements such as lenses, conventionally a method has been used to coat the surface of the optical element with an anti-reflection film. As with the optical system in
When using a lens system with a small number, it has been difficult to obtain sufficiently good prevention characteristics. Furthermore, as can be seen from the manner in which the multiple reflected light is generated as shown in FIG. 2, the main beam and the multiple reflected light overlap, and therefore cannot be easily separated.

The purpose of the present invention is to solve the above-mentioned conventional problems and eliminate their drawbacks, and to prevent the multiple reflected light generated in the optical system from being deflected and overlapped with the original light beam to be used for recording. An object of the present invention is to provide an optical system for deflecting a light beam that prevents ghost images, interference fringes, etc. caused by multiple reflected light from being mixed into recorded information.

That is, the optical system for light beam deflection of the present invention is designed to prevent the multiple reflected light generated in the optical system from overlapping with the original light beam. The light beam is arranged so that it is incident on a position off the optical axis of the lens element, and if necessary, the multiple reflected light can be blocked and removed with a mask etc., and the light beam is directed in the first direction and in the corresponding direction. In an optical system used for two-dimensional deflection of a light beam to record information on a recording medium by deflecting the light beam in a second direction orthogonal to the first direction, the light beam is deflected in the first direction and the second direction, respectively. The lens element interposed between the first and second optical deflectors that
The incident position of the one-dimensionally deflected light beam incident from the optical deflector is shifted from the position of the optical axis of the lens element in a direction perpendicular to the plane of deflection of the one-dimensionally deflected light beam. The present invention is characterized in that the relative positions of the second optical deflector and the lens element are set.

Hereinafter, the present invention will be explained in detail with reference to embodiments with reference to the drawings.

First, FIG. 3 shows the basic configuration of the optical system of the present invention, which prevents the multiple reflected light generated in the optical system from overlapping the original light beam.The optical system with the configuration shown in FIG. The beam is configured to move parallel to the optical axis of the optical system in a plane perpendicular to the one-dimensional deflection plane. At the same time, the multiple reflected light 19'
to occur. However, since the incident position of the incident light beam 11' is shifted from the position of the optical axis of the lens 15, the multiple reflected light 19' does not overlap with the main deflected beam 18' and can be blocked by a mask or the like if necessary. Move in the direction you can.

FIG. 4 shows an example of a specific configuration of the optical system of the present invention based on the principle configuration shown in FIG. 3 above. Fourth
The optical system having the configuration shown in FIG. 4A is viewed from a direction perpendicular to the deflection direction of the first optical deflector 3 in the configuration shown in FIG. The optical system shown in FIG. 4a is viewed from a direction parallel to the deflection direction of the first optical deflector 3. In addition, FIG. 4c shows the state of spread of the light beam when the lens surfaces of lenses 21 and 23 in the optical system shown in FIGS. 4a and 4b are viewed from the direction in which the light beam travels. In the figure, the dotted line shows the state in which the light beam is deflected and spread within the plane that includes the optical axis, and the solid line shows the state in which the light beam is deflected and spread in the plane that is off the optical axis according to the present invention. This shows the spread of the deflected beam within the area.

As can be seen from each of FIGS.
The light beam 10 that is parallel-translated in a direction perpendicular to the direction of deflection of the first beam 10 and deflected in a one-dimensional direction is
Most of the multiple reflection light generated when passing through the relay lens 21 is blocked and removed by the first mask 22. Furthermore, most of the multiple reflection light generated by the second relay lens 23 is blocked and removed by the second mask 24, and almost only the main beam 12 is transmitted to the second optical deflector 5 and the imaging lens 24.
5 and reach the recording medium 7.

Relay lens 2 in the configuration shown in Figure 4
1 and 23 are both single lenses, but in reality it is necessary to use a lens with a complicated configuration such as a photographic lens with little aberration, and even when using a relay lens with such a complicated configuration, According to the optical system having the configuration shown in FIG. 4, the complicated multiple reflected light generated by those relay lenses can be
It can be removed very effectively in the same manner as described above.

Note that, of course, if the multiple reflected light exits outside the effective aperture surface of the optical system, the first and second masks 22 and 24 in the configuration shown in FIG. 4 can be omitted.

As is clear from the above description, according to the present invention, in order to remove multiple reflected light that occurs in the optical system of a recording device using deflection of a light beam and significantly deteriorates the quality of recorded information, The effects of multiple reflections, especially those caused by multiple reflections, can be avoided using relatively inexpensive ordinary photographic lenses, without the use of expensive lenses with special configurations or lenses with anti-reflection coatings specifically designed to prevent such effects. , it is possible to remove fringes on a recorded image due to interference of multiple reflected light generated in a portion close to the optical axis of the lens with extremely easy adjustment.

In the configuration example shown in FIG. 4, there is no need to tilt the optical axis of the relay lens system, so the design of the optical system is relatively simple and adjustment is easy.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a conventional recording device using light beam deflection, Fig. 2 is a side view showing the mode of multiple reflected light generation in the optical system, and Fig. 3 is the principle of the optical system of the present invention. FIGS. 4a, 4b and 4c are a side view and a front view, respectively, showing an example of a specific structure of the optical system of the present invention. 1... Laser oscillator, 2... Optical modulator, 3, 5
...Light deflector, 4...Relay lens system, 6...Imaging optical system, 7...Recording medium, 8...Input signal, 9
... Laser light beam, 10 ... Modulated light beam,
11, 11', 11'', 12, 13... Deflected light beam, 14... Imaging light beam, 15... Lens, 1
6, 17... Lens surface, 18, 18', 18''...
Main beam, 19, 19', 19''...Multiple reflected light,
20... Convergence surface, 21, 23... Relay lens,
22, 24...mask, 25...imaging lens.

Claims (1)

[Claims] 1. In an optical system used for two-dimensional deflection of a light beam to record information on a recording medium by deflecting the light beam in a first direction and a second direction perpendicular to the first direction, the light beam is deflected in the second direction. The incident position of the one-dimensional deflected light beam that is incident from the first optical deflector on a lens element interposed between the first and second optical deflectors that are deflected in the first and second directions, respectively, is determined from the lens element. The first and second beams are deflected from the optical axis of the element in a direction perpendicular to the plane of deflection of the one-dimensionally deflected light beam.
An optical system for deflecting a light beam, characterized in that the relative positions of the light deflector and the lens element are set.