JPS62232611A - Laser exposing device for image scanning and recording device - Google Patents

Abstract

PURPOSE:To eliminate a variation of a size of an image, and to improve the workability by forming an image of an aperture on a recording surface by an image forming optical system, so that a main light beam of each laser beam for forming its line becomes parallel to an optical axis. CONSTITUTION:Plural lines of parallel laser beams B4 which have passed through an aperture 5 form an aperture image on a recording surface G as an image 14 whose beam pitch has been reduced, by an image forming optical system 10 consisting of a telecentric optical system. In this case, a main light beam 15 of each laser beam B6 for forming the image 14 becomes parallel rays to an optical axis 16. In this way, even if a shift DELTAD is generated between an image forming surface Q and the recording surface G of the image forming optical system 10, a size of the image is not varied.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention is applicable to a J3 image scanning recording apparatus for recording a desired image using a light-modulated laser beam, such as a laser plotter or a color scanner. The present invention relates to a laser exposure device.

<Prior Art> As an image scanning recording device as described above, a laser plotter as shown in FIG. 8, for example, is known. This laser plotter includes a console section 21 and a data processing section 2 that performs processing on data inputted via a medium such as a magnetic tape.
2, a data conversion generation section 23 that converts the data processed by the data processing section 22 into a required recording signal, and a recording section 24 that scans and records an image on a photosensitive sheet on a recording cylinder 25 based on the recording signal. It is designed to record high-precision master patterns on printed wiring boards, etc., by exposure at high speed.

The recording section 24 of the image scanning recording apparatus as described above is equipped with a laser exposure device 30 as shown in FIG. 9, for example, in order to record a desired pattern. As disclosed in Japanese Patent Application Laid-Open No. 6O-169F320 previously proposed by the present applicant, a laser beam B l l from a laser light source 31 is split into a plurality of parallel laser beams B l 2 by a beam splitter 32. The plurality of laser beams B1□ are each independently modulated by a multi-channel acoustic or electro-optic modulator 33 according to the pattern signal,
The beam pitch of the plurality of modulated parallel laser beams B11 is reduced to a required value by an imaging optical system 34 consisting of a zoom lens 35 and an imaging lens 36, and an image 14 is formed on the imaging plane G, and the image 14 is recorded. This is after the configuration is such that a desired pattern image is exposed and recorded on the photosensitive sheet 26 wrapped around the shilling 25.

<Problems to be Solved by the Invention> The laser exposure apparatus 30 of the above-mentioned conventional example can perform exposure by adjusting the beam pinch of the light spot array image projected onto the imaging plane G using an optical system with a simple configuration. It is very good, but
There is room for further improvement regarding the following points.

(a) In the conventional example described above, when the beam compression optical system 34 reduces the beam pitch and forms a required light spot array image, the principal ray 55 of each laser beam is is converged by the imaging lens 36 to obtain the required light spot sequence 'm W + on the imaging position Q.
Due to the deviation ΔD between the imaging position Q and the recording position G, the width W of the light spot array on the recording position G changes.

Furthermore, with a zoom lens, the beam pitch is infinitely variable! For example, the photosensitive sheet 26 to be used
Since the above-mentioned deviation ΔD changes when using beams with different thicknesses, it is inconvenient to need to adjust the beam pitch in such cases.
! The adjustment work is also not easy.

(b) Furthermore, in the conventional example described above, even if an image is exposed and recorded on a lithium-ion film, the edge sharpness of the image may not be sufficient depending on the developing conditions and the like. This is thought to be due to the following reasons.

That is, the light intensity distribution of the laser beam B l + emitted from the laser light source 31 is not uniform, and has, for example, a Uth distribution I (solid line portion) as shown in FIG.
The light intensity is extremely low at the outer periphery of the beam, so when an image is drawn using such a laser beam, the edges of the image may vary depending on the developing conditions, even if a high-contrast lithium-type photosensitive material is used. This is because the required concentration may not be obtained.

In order to solve this problem, it is desirable to make the light intensity within the beam cross section uniform at a required level. For example, seven vertices 61 of the beam shaping plate 51 may be illuminated.

However, since the emitted beam Bl+ from the laser beam a31 originally has a small diameter, the aperture 61 for extracting the uniform light amount portion J at the center needs to be made small, and in doing so, the wavelength of the laser beam and the Due to this relationship, diffraction development has a large influence, and a light intensity distribution that should be uniform cannot be obtained. Moreover, it is not easy to form such small apertures with high precision.

The present invention has been made in view of the above circumstances, and has an object to prevent the beam pitch from changing even if the deviation between the image forming surface and the recording surface of the image forming optical system changes, and to prevent the edge of the image line from changing. The purpose is to improve the sharpness of the image.

<Means for Solving the Problems> In order to achieve the above object, the present invention improves the conventional laser exposure apparatus as shown in FIGS. 1 to 4, for example.

That is, an image 14 of the aperture 5 placed before entering the imaging optical system 10 is imaged onto the recording surface G by an imaging optical system constituted by one or more telecentric optical systems, and a line is formed. The main ray 15 of each laser beam 66 is parallel to the optical axis 16.

<Operation> Multiple parallel laser beams B4 passing through the aperture are
An aperture image is formed on the recording surface G as an image 14 with a reduced beam pitch by an imaging optical system 10 comprising a telesend link optical system.

At this time, the chief ray 15 of each laser beam B6 forming the image 14 becomes a parallel ray with respect to the optical axis 16.

As a result, even if a deviation ΔD occurs between the imaging surface Q of the imaging optical system 10 and the recording surface G, the dimensions of the image do not change as in the conventional example.

<Example> Hereinafter, an example of a laser exposure apparatus according to the present invention will be described based on FIGS. 1 to 5.

FIG. 1(A) is a perspective view showing an outline of a laser exposure apparatus, and in this figure, reference numeral 1 is a laser light source, 3 is a beam expander, 4 is a beam splitter (splitting means), and 5 is a laser light source.
(5a/5111) is a beam shaping plate, 6 is an aperture,
7 is a multi-channel optical modulator, 8 is a slit plate for blocking O-order diffracted light, 2 and 9a and 9b are mirrors, and 10 is an imaging optical system.

The beam expander 3 includes a pair of lenses 3a and 3b, and serves to expand the diameter of the laser beam B emitted from the laser light source 1.

The beam shaping plate 5a is for obtaining a relatively uniform light intensity distribution by extracting the central portion of the laser beam B2 expanded by the beam expander 3.

That is, the light intensity distribution of the laser light beam B emitted from the laser light @1 is not uniform, and as mentioned above, the light intensity is extremely low at the outer periphery of the beam. When an image is drawn using a laser beam, the edges of the image may not have the required density depending on the developing conditions even if a high-contrast lithium-type photosensitive material is used.

Therefore, the beam shaping plate 5a is used after the beam has passed through the beam expander 3, and is used as a means to solve this problem, since it may be one of the causes of a decrease in the sharpness of the edge of the image. That is, this beam shaping plate 5a has a single aperture 6a and is arranged between the beam expander 3 and the beam splitter 4, and as shown in FIG. and the size are defined, and it is possible to extract a portion of the relatively uniform light intensity distribution J at the center of the expanded laser beam B2. As a result, the decrease in light intensity at the outer periphery of the beam can be ignored. The line drawn using the laser beam extracted in this manner has the advantage of ensuring sufficient edge sharpness.

When the beam shaping plate 5a is provided after the beam expander 3 as shown in FIG. 1(A), the beam expander 3
After making the diameter of the laser beam B2 sufficiently large, the beam can be shaped, so that the diameter of the aperture 6a can be enlarged to such an extent that the influence of the diffraction phenomenon can be ignored.

In this case, it is advantageous to form the seven pernaya with high precision. Incidentally, in this embodiment, the diameter of this aperture 6a is approximately 1.5 mm. Sn+/m
That's about it.

Note that a beam shaping plate 5b according to another embodiment shown in FIG. 1(B) may be used in place of the beam shaping plate 5a. The beam shaping plate 5b according to this other embodiment is provided between the beam splitter 4 and the optical modulator 7, and has a plurality of seven vertices 6b opened in series corresponding to the parallel beam B emitted from the beam splitter 4. Basically, similar to the beam shaping plate 5a described above, each laser beam B is shaped by the aperture 6b and has a relatively uniform light intensity before entering the optical modulator 7. Part J is taken out.

The beam splitter 4 is for splitting the expanded laser beam B2 into a plurality of parallel laser beams B.
As described in Japanese Patent No. 122135, it is equipped with a glass plate having parallel planes, one plane is coated with a coating that forms a completely reflective surface, and the other plane is coated with a coating that emits light from the plane. A coating is applied to change the transmittance in stages so that the light intensity of each of the parallel beams B is uniform.

The multi-channel optical modulator 7 is of an acousto-optic type, for example, and as is well known, a plurality of ultrasonic excitation members are attached on a single acousto-optic medium, and an acoustic wave corresponding to the excitation member is attached. Each parallel laser beam B is made incident on the optical medium portion, and each incident laser beam B is configured to be independently modulated based on a control signal issued based on a bang signal.

The slit plate 8 is for passing only the first-order diffracted light modulated by the light modulation adjuster 7 and blocking and removing the zero-order diffracted light.

A plurality of parallel laser beams B passing through the slithering plate 8,
The direction of the light is changed by the next two plane mirrors 9a and 9b, and the light is incident on the imaging optical system 10.

The imaging optical system 10 is configured as a telesend link optical system in which two telescope optical systems 11 and 12 are optically connected telecentrically, and with this configuration, the beam pitch of the plurality of parallel beams B is compressed and the resulting An image 14 having a required width W1 is formed on the image plane F.

FIG. 2 is a schematic diagram of this imaging optical system 10.

L and L2 indicate the objective lens and eyepiece lens of the telescope optical system 11 at the front stage, respectively. This optical system 11 constitutes one telecentric optical system as a whole, and a beam shaping plate 5 is arranged at the front focal position F1 of the objective lens L1.
The plurality of parallel beams B4 from the converging lens 'X:L2 are emitted as the same number of parallel beams B again, and 11
1 lens L2 rear focal position F 23 front stage reduction magnification M
, the beam pitch is compressed to form a small image 13.

L and L4 respectively indicate the objective lens and eyepiece of the rear-stage telescope optical system 12. Like the front-stage optical system 11, this optical system 12 constitutes one telesend link optical system as a whole, and the objective lens L, Front focal position F 21
The plurality of parallel beams B from the image 13 formed in An image 14 is formed.

The rear-stage telescope optical system 12 includes a zoom lens L therein, so that the beam pitch of the image 14 can be adjusted steplessly.

As described above, when the telescope optical systems 11 and 12 are connected in two stages, the magnification of each can be made relatively low, resulting in an advantage that aberrations can be made smaller than when the telescope optical systems are reduced in one stage. By the way, in this embodiment, the beam compression optical system 1
The overall reduction magnification of 0 can be adjusted steplessly from 1/150 to 1/300.

The zoom lens L is not necessarily limited to the rear optical system 12, but may instead be included in the front optical system 11, or if the reduction magnification is not adjusted steplessly, as shown in FIG. It can be abbreviated to

The advantage of configuring the imaging optical system 10 as a telecentric optical system is that the imaging position F is fixed as shown in figure fjrJ4.
Even if a deviation ΔD occurs between Q and the recording position G, the dimensions W1 and W2 of the image at each position are substantially equal. That is, this is because, as described above, the chief ray 15 of each laser beam B6 emitted from the eyepiece L at the subsequent stage is parallel to the optical axis 16 of this optical system 12. However, since such a positional shift means that the imaging state of each beam deteriorates, it is desirable that the imaging position F and the recording position G be as close as possible.

In the above embodiment, the imaging optical system 10 is an example in which the telescope optical systems 11 and 12 are connected in two stages, but the invention is not limited to this, and as long as the imaging optical system 10 as a whole constitutes a telecentric optical system, It may be a single type or a type connected in three or more stages.

The blocking slit plate 8 may have a plurality of apertures opened in series, or a plurality of apertures opened in series may be provided at appropriate positions between the imaging optical system and the multi-channel optical modulator. It may be provided.

<Effects of the Invention> According to the present invention, even if there is a misalignment between the imaging surface of the imaging optical system and the recording surface, the dimensions of the image do not change as in the conventional example. Therefore, even if the thickness of the photosensitive sheet used changes, for example, all you have to do is adjust the focus, and you don't have to worry about changes in the image dimensions at all.
Workability is improved and assembly and adjustment of the imaging optical system becomes easier.

[Brief explanation of drawings]

1 to 5 show an embodiment of a laser exposure apparatus according to the present invention, and FIG. 1(A) is a schematic perspective view of the laser exposure apparatus;
FIG. 1(B) is a perspective view of the main parts of another embodiment, FIG. 2 is a plan view showing an outline of the beam compression optical system 10 in FIG. 1, and FIG. 3 is a diagram showing another embodiment of the imaging optical system. Figure 2 Correspondence diagram, 4th
The figure is a plan view showing the mode of the beam near the imaging position by the imaging optical system, and FIGS. 5 and 6 are explanatory diagrams showing the mode of beam shaping by the beam shaping plate, respectively. @Figure 7-9
The figure shows a conventional example, FIG. 7 is a plan view showing the state of the beam near the imaging position by the conventional imaging optical system, and FIG. 8 shows an example of an image scanning recording device using a laser exposure device. FIG. 9 is a perspective view of a conventional laser exposure apparatus. DESCRIPTION OF SYMBOLS 1... Laser light source, 3... Beam expander, 4... Beam splitter, 5 (5a, 5b).
...Beam shaping plate, 6 (6a, 6b)...Aperture, 7...Multi-channel optical modulator, 10...
Imaging optical system, 11/12... Telescope optical system,
14...Statue. Figure 1 (A') Figure 1 (B)

Claims (1)

[Claims] 1. A laser beam from a laser light source is divided into a plurality of parallel laser beams by a beam splitting means, and each of the plurality of laser beams is modulated independently by a multi-channel optical modulator. In a laser exposure device of an image scanning recording device configured to project multiple parallel laser beams onto a recording surface via an imaging optical system composed of multiple lenses, a The image of the aperture is formed on the recording surface by an imaging optical system composed of one or more telecentric optical systems, and the chief ray of each laser beam forming the line is parallel to the optical axis. A laser exposure device 2 of an image scanning and recording device characterized in that the imaging optical system includes a zoom lens, a laser exposure device 3 of the image scanning and recording device according to claim 1, and a beam According to claim 1, an expander is provided to expand the diameter of a laser beam emitted from a laser light source, and the aperture is irradiated with a laser beam of parts whose light intensity distribution is relatively uniform. The laser exposure device 4 of the image scanning recording device according to claim 3, wherein the beam shaping plate has a single aperture and is arranged between the beam expander and the beam splitter. The laser exposure device 5 is an image scanning recording device according to claim 3, wherein the beam shaping plate has a plurality of serially opened apertures and is arranged between a beam splitter and a multi-channel optical modulator. A laser exposure device 6 for an image scanning and recording device according to claim 3, wherein the beam-shaped plate is arranged between the imaging optical system and the multi-channel optical modulator.