JPH09247367A - Picture reading optical system and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain miniaturization and to facilitate taking and turning by irradiating an object with highly diffracted light beams obtained by optimizing the wave front of irradiating light and outputting 0-order diffracted light beams as picture reading detection light concerning its reflected light. SOLUTION: A transmitting type diffraction grating 3 is arranged between a light source 2 and a picture 10. Light from the light source 2 is diffracted by the grating 3, a diffraction pattern is formed at the grating 3 so as to make highly diffracted light beams parallel, and this parallel light enters vertically with respect to the picture 10. When the parallel light reflected by the picture 10 passes through the grating 3, the light is also diffracted and the highly diffracted light beams of the reflected parallel light is made scatterd light by the diffraction pattern. However, the 0-order diffracted light beams of the reflected parallel light still remains parallel light and this parallel light is outputted toward the photodetective part which is not shown in figure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading optical system and an image reading optical device which can be used in an input section of an optical information processing device such as an optical computer or an optical character reading device (OCR).

[0002]

2. Description of the Related Art An image of an object is read by collimating light emitted from a light source with a lens, irradiating the light onto the object, and obtaining parallel light reflected by the object. If this is set, this reading (removal of reflected light)
If the lens is present on the optical path of, the reflected collimated light is condensed by the lens and returns to the light source, so that the shadow is cast by the light source and an output cannot be obtained. Therefore, as shown in FIG. 6, the light source 51 and the lens 52 are provided at positions off the reflected optical path, and the light from the light source 51 is reflected by the beam splitter 5.
There is known an image reading optical system in which the light reflected by the object 3 is guided to the object 54 and the light reflected by the object 54 is transmitted and output. Such an optical system can also be seen in a metallographic microscope and the like.

[0003]

However, in the structure shown in FIG. 6 described above, the light source and the optical system associated with the light source are largely projected in the direction perpendicular to the optical axis. This is not only an obstacle to miniaturization, but also inconvenient for handling.

In view of the above-mentioned circumstances, it is an object of the present invention to provide an image reading optical system and an image reading optical device which are small in size and have an illuminating device which does not project from the main body.

[0005]

An image reading optical system according to the present invention is an image reading optical system in which light is emitted toward an object and the image of the object is read by the light reflected by the object. In the system, as a light source for irradiating the light, as an image reading detection light related to the higher-order diffracted light reflected by the object while irradiating the object with a higher-order diffracted light with the wavefront of the light from the light source made appropriate And a diffraction grating that outputs 0th-order diffracted light. Further, in an image reading optical system in which light is irradiated toward an object and the image of the object is read by the light reflected by the object, a light source that emits the light and a light from the light source. And irradiating the object with diffracted light having an optimized wavefront, and outputting a diffracted light as image reading detection light relating to the diffracted light of a different order from the diffracted light reflected by the object. It is characterized by that. Further, the higher-order diffracted light or diffracted light obtained by optimizing the wavefront of the light from the light source may be substantially parallel light, and the 0th-order diffracted light or diffracted light as the image reading detection light may be substantially parallel light. .

With the above configuration, for example, parallel light as light having an appropriate wavefront can be generated in the first-order diffracted light of the diffraction grating, and the diffraction grating is used for the parallel light reflected by the object. Since it outputs diffracted light of a different order (for example, 0th-order diffracted light) from the irradiation light of the light, there is no problem in the case of obtaining parallel light with a lens as in the conventional case, and the diffraction grating is applied to the object. The light source can be arranged on the optical axis through which the reflected light passes, and the light source can be arranged on or near the optical axis through which the light reflected by the object passes, so that miniaturization is possible.

Further, the image reading optical apparatus of the present invention is characterized in that a light absorbing wall is provided around the image reading optical system having the above construction.

In the image reading optical system including the above-mentioned diffraction grating, the light which is not substantially collimated out of the light from the light source becomes diffused light and travels away from the target surface of the object. I will get out. Further, light other than, for example, the 0th-order diffracted light that has passed through the diffraction grating and is substantially parallel light reflected on the surface of the object also becomes diffused light, which may become stray light and adversely affect reading accuracy. In the image reading optical device having the above configuration, since the light absorbing wall is provided around the image reading optical system, the diffused light is absorbed by the light absorbing wall.

The light source may be arranged on the light absorbing wall. With such a configuration, since the light absorbing wall serves as a placement seat for the light source, it is not necessary to form a separate placement seat,
The manufacturing of the image reading optical device can be simplified.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing an image reading optical system 1 of the present invention in which parallel light is emitted toward an image 10 and the image is read by the reflected parallel light. The image reading optical system 1 has a light source 2 arranged on an optical path through which the light reflected by the image 10 passes. As the light source 2,
An infrared semiconductor laser with a wavelength of 780 nm was used. Also,
The light source 2 is arranged at the center of the optical axis of the reflected parallel light, but the shadow caused by the light source 2 on the reflected light is relatively small.

A transmission type diffraction grating 3 is arranged between the light source 2 and the image 10. The light from the light source 2 is diffracted by the diffraction grating 3, but the diffraction grating 3 is formed with a diffraction pattern so that the high-order diffracted light (first-order diffracted light in this embodiment) becomes parallel light. The parallel light is incident perpendicularly on the image 10. The parallel light reflected by the image 10 (hereinafter abbreviated as reflected parallel light) is also diffracted when passing through the diffraction grating 3, and due to the diffraction pattern, the higher-order diffracted light of the reflected parallel light becomes diffused light. The 0th-order diffracted light of the reflected parallel light remains the parallel light, and the parallel light is output toward the light receiving unit (not shown). That is, the forward path uses the first-order diffracted light and the return path is 0
It is an optical system that uses the second-order diffracted light.

FIG. 2 is an enlarged sectional view of the diffraction grating 3.
The diffraction grating 3 is made of, for example, a quartz plate having a thickness of 1 mm. Further, the grating pattern of the diffraction grating 3 is set so that the ratio of the 1st-order diffracted light and the 0th-order diffracted light is approximately 1: 1. The grid pattern in this case is a rectangular groove with a groove depth of 0.5 μm.
And Of course, the lattice pattern is not limited to the rectangular groove.

As described above, the image reading optical system 1 generates parallel light in the first-order diffracted light of the diffraction grating 3, and the diffraction grating 3 outputs the 0th-order diffracted light of the parallel light reflected by the image 10. Therefore, there is no problem in obtaining parallel light with a lens. Then, the light source 2 and the diffraction grating 3
Can be arranged on the reflection optical path, so that no protruding portion is generated.

FIG. 3 is a schematic diagram showing another configuration example of the image reading optical device 11. This image reading optical device 11
In the image reading optical system 1, the semiconductor laser located at the center of the optical axis is displaced and arranged near the optical axis, and the light absorbing wall 15 is provided. Light absorbing wall 1
For example, 5 is formed by applying a light absorbing paint.

In the structure shown in FIG. 1, the shadow of the semiconductor laser is produced. Further, of the light from the light source 2, the light that has not been collimated becomes diffused light and the target image 10 is obtained.
It goes away from. Similarly, the parallel light reflected by the image 10 other than the 0th-order diffracted light passing through the diffraction grating 3 also becomes diffused light and becomes stray light, which may adversely affect the reading accuracy.

On the other hand, with the configuration shown in FIG.
Since the light absorbing wall 15 is provided around the image reading optical system 1, the diffused light is absorbed by the light absorbing wall 15. Further, since the light source 2 provided in the image reading optical system 1 is arranged so as to be off the center of the optical axis of the reflected parallel light, the influence of the shadow of the light source 2 generated on the reflected parallel light does not occur. Further, since the light source 2 is formed on the light absorbing wall 15 and the light absorbing wall 15 serves as an arrangement seat for the light source 2, it is not necessary to form another arrangement seat, and the image reading optical device 11 is manufactured. Can be simplified.

In this embodiment, the transmission type diffraction grating 3 is used, but a reflection type diffraction grating may be used to form the image reading optical system. In this case, for example, as shown in FIG. 4, the diffraction grating 31 is configured so as to transmit approximately half of the incident light and reflect half of the incident light, and is arranged at an angle of approximately 45 ° with respect to the optical axis. This angle is not limited to about 45 ° and can be freely determined by the design of the diffraction grating. Then, the light source 2 is arranged between the image 10 and the diffraction grating 31, and emits light toward the diffraction grating 31 side. The diffraction grating 31 is formed by forming a diffraction pattern so that high-order diffracted light (for example, first-order diffracted light) becomes parallel light, and this parallel light is incident perpendicularly to the image 10.
The parallel light reflected by the image 10 passes through the diffraction grating 31, and the 0th-order diffracted light (parallel light) is output toward a light receiving unit (not shown) provided at a position facing the image 10. Become. Alternatively, as shown in FIG.
Reference numeral 2 is configured to reflect all the incident light, and is arranged at an angle of about 45 ° with respect to the optical axis. And the light source 2 is the image 1
It is arranged between 0 and the diffraction grating 32, and emits light toward the diffraction grating 32 side. The diffraction grating 32 is formed by forming a diffraction pattern so that high-order diffracted light (for example, first-order diffracted light) becomes parallel light, and this parallel light is incident perpendicularly to the image 10. The parallel light reflected by the image 10 is reflected by the diffraction grating 32, and the 0th-order diffracted light (parallel light) is output toward a light receiving unit (not shown) provided on the side of the image 10.

The light source 2 is not limited to a semiconductor laser but may be a small solid laser or the like, and a monochromatic light source such as a sodium lamp or a light emitting diode can be used if it is not necessary to be coherent.

[0020]

As described above, according to the present invention,
Since the image reading optical system can be constructed in a small size and no projecting portion is formed, it is easy to handle. When a light absorbing wall is provided between the image reading optical systems,
Unwanted diffused light can be absorbed by the light absorbing wall. Further, when the light source is arranged on the light absorbing wall, the light absorbing wall serves as the arrangement seat of the light source, so that it is not necessary to separately form the arrangement seat, and the manufacturing of the image reading optical device can be simplified. Produce an effect.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an image reading optical system of the present invention.

FIG. 2 is a sectional view of a diffraction grating used in the image reading optical system of the present invention.

FIG. 3 is a schematic view showing another example of the image reading optical system of the present invention.

FIG. 4 is a schematic view showing another example of the image reading optical system of the present invention.

FIG. 5 is a schematic view showing another example of the image reading optical system of the present invention.

FIG. 6 is a schematic view showing a conventional image reading optical system.

[Explanation of symbols]

 1 image reading optical system 2 light source 3 diffraction grating 10 image 15 light absorbing wall

Front page continuation (72) Inventor Hiroshi Tsuchiya 2-5-5 Keihan Hondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Toru Ishikawa 2-5-5 Keihan-hondori, Moriguchi-shi, Osaka Sanyo Denki Co., Ltd. (72) Inventor Akira Ibaraki 2-5-5 Keihan Hondori, Moriguchi City, Osaka Sanyo Denki Co., Ltd.

Claims (5)

[Claims] 1. An image reading optical system configured to irradiate an object with light and read the image of the object with the light reflected by the object, a light source for irradiating the light, and the light source. And a diffraction grating for irradiating an object with a higher-order diffracted light with an appropriate wavefront of the light from and outputting a 0th-order diffracted light as image reading detection light related to the higher-order diffracted light reflected by the object. An image reading optical system characterized by the above. 2. An image reading optical system configured to irradiate an object with light and read the image of the object with the light reflected by the object, and a light source for irradiating the light, and the light source. Diffraction that irradiates an object with diffracted light with an appropriate wavefront of the light from and outputs diffracted light as image reading detection light related to the diffracted light of a different order from the diffracted light reflected by the object. An image reading optical system comprising a grating. 3. The high-order diffracted light or diffracted light obtained by optimizing the wavefront of the light from the light source is substantially parallel light, and the 0th-order diffracted light or diffracted light as the image reading detection light is substantially parallel light. The image reading optical device according to claim 1, wherein 4. An image reading optical apparatus, wherein a light absorbing wall is provided around the image reading optical system according to any one of claims 1 to 3. 5. The image reading optical device according to claim 4, wherein a light source is arranged on the light absorbing wall.