JPH0554754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of the Invention) The present invention relates to an optical travel reading device, and more particularly, to an optical scanning device, which generates surface acoustic waves in an optical waveguide, and deflects guided light by the diffraction action of the surface acoustic waves. The present invention relates to an optical scanning reading device that performs optical scanning.

(Prior Art) As is well known, in the past, an image recorded on the original has been read by scanning the original with light and photoelectrically detecting the transmitted light, reflected light, or emitted light from the original. Various types of phototactic reading devices have been provided. Conventional optical scanning devices that scan the reading light one-dimensionally in such reading devices include devices that deflect and scan the light beam using a mechanical optical deflector such as a galvanometer mirror or a polygon mirror (rotating polygon mirror); There are known devices in which a light beam is deflected and scanned by an optical deflector using an optical deflection element, such as an electro-optic optical deflector (electro-optic optical deflector) or an acousto-optical optical deflector (AOD).

However, the above-mentioned mechanical optical deflector has disadvantages in that it is susceptible to vibrations, has low mechanical durability, and is troublesome to adjust. Furthermore, there is a problem in that the optical system becomes large in order to swing and deflect the light beam, leading to an increase in the size of the reading device.

Furthermore, optical scanning devices using EOD or AOD also have the problem of increasing the size of the reading device because the light beam is waved and deflected in the same way as described above. In particular, since the EOD and AOD cannot have a large optical deflection angle, the optical system tends to be even larger than when using a mechanical optical deflector.

Therefore, the guided light traveling inside the optical waveguide is called a surface acoustic wave.
An optical scanning device that scans light by deflecting the light using a SAW (Surface Acoustic Wave) and changing the angle of this deflection has been considered. This optical scanning device includes an optical waveguide formed from a material that allows surface acoustic waves to propagate, a light source that inputs light into the optical waveguide, and an optical system that converts the guided light traveling through the optical waveguide into parallel light. , a means for generating a surface acoustic wave in an optical waveguide that propagates in a direction intersecting the optical path of the guided light and deflects the guided light; and a means for generating a surface acoustic wave whose frequency continuously changes. An optical scanning reading device using such an optical scanning device has excellent durability and vibration resistance, and can be made relatively compact.

However, in the case of an optical scanning reading device using an optical scanning device as described above, an optical element such as a prism coupler is provided in order to emit the polarized waveguide light out of the optical waveguide, and furthermore, an optical element such as a prism coupler is provided to emit the deflected guided light out of the optical waveguide. Since a focusing lens is provided to focus the scanned light onto the document to be read, there is a problem in that sufficient miniaturization cannot be achieved. Furthermore, the deflection of the guided light described above is due to Bragg diffraction based on the acousto-optic interaction between the guided light and the surface acoustic wave, but in this type of optical deflection, the deflection angle cannot be set large, and therefore the optical scanning width is If it is attempted to set a large value, the distance from the optical waveguide to the document to be read must be set long, resulting in a problem that the reading device becomes larger.

Furthermore, when using the above prism coupler, it is necessary to precisely adjust the gap between the prism bottom surface and the optical waveguide, which requires an expensive fine adjustment mechanism, and the prism coupler is also expensive. , the reading device becomes expensive.

Furthermore, in addition to the above-mentioned adjustment work, it is also necessary to precisely adjust the relative positions of the optical waveguide and the focusing lens, so that adjustment of a reading device using the above-mentioned optical scanning device becomes extremely troublesome. Since many adjustments are required, this type of phototaxis reading device has low reliability.

Furthermore, when the guided light is emitted out of the optical waveguide using the prism coupler, the shape of the emitted light is
Since the beam becomes parallel in the direction parallel to the prism base and diverging in the direction perpendicular to the prism base, a special focusing lens other than a normal spherical lens is required to focus the scanning light into a circular spot. There are also problems.

Furthermore, when using the prism coupler, focusing lens, etc. mentioned above, if defects occur in these optical elements or the end face of the optical waveguide, the shape of the scanning beam spot will be affected (particularly when converging light from the end face of the optical waveguide, this There is also the problem that a defect in the end face directly leads to a chip in the scanning beam spot), making precise scanning impossible.

(Objective of the Invention) Therefore, an object of the present invention is to provide an optical scanning reading device that can solve the various problems described above.

(Structure of the Invention) The optical scanning reading device of the present invention is an optical scanning device comprising the above-described optical waveguide, a light source, an optical system that converts the guided light into parallel light, a surface acoustic wave generating means, and a drive circuit. A focusing grating (FGC) that emits the polarized guided light outside the optical waveguide and focuses it in a space outside the waveguide.
and a light-reflecting layer on each of the opposing surfaces,
A glass block is provided which is bonded to the substrate of the optical waveguide so that the light emitted from the optical waveguide is repeatedly reflected between both surfaces before reaching the focal point, and in addition to this optical scanning device. , a sub-scanning means for relatively moving an optical waveguide and a read original placed at a position where the focused light is irradiated in a direction substantially perpendicular to the direction of scanning of the light by the deflection; and irradiation of the light. The device is equipped with a photodetector that photoelectrically detects transmitted light, reflected light, or emitted light from the original document obtained by the method.

(Function) Deflection of guided light by surface acoustic waves has been known for a long time, but will be briefly explained here. As shown in FIG. 1, for example, the traveling direction of a surface acoustic wave 12 generated by an interdigital transducer (IDT) 15 and propagating through an optical waveguide 11, and the traveling direction of a guided light 13 are shown. If the angle (Bragg angle) formed by
It becomes 2θ. Let the wavelength and effective refractive index of the guided light 13 be λ and Ne, and the wavelength and frequency of the surface acoustic wave 12,
If the velocities are Λ, f, and v, respectively, then 2θ=2sin ^-1 (λ/2Ne・Λ) λ/Ne・Λ = λ・f/Ne・v, and 2θ, that is, δ, is the frequency f of the surface acoustic wave. Almost proportional. Therefore, if the frequency of the pulsed voltage applied to the electrode pair 15 is continuously changed to continuously change the frequency of the surface acoustic wave 12, the deflection angle δ will be continuously changed. Therefore, if this guided light 13 is taken out of the optical waveguide 11,
The light scans in one dimension.

On the other hand, the condensing diffraction grating (FGC) 14 is a diffraction grating having bends and chirps, and is a diffraction grating that has curves and chirps.
A plane wave inside the optical waveguide 11 and a spherical wave having a focal point at a point in space outside the optical waveguide 11 are directly coupled. Therefore, if this light-condensing diffraction grating 14 is provided on the surface of the optical waveguide in the optical path of the guided wave 13 deflected as described above, the deflected light can be taken out of the optical waveguide 11 and furthermore, It is focused in the space outside the wave path 11. If the original 31 to be read is placed at the position where this light is focused, the original 31 will be one-dimensionally scanned by the focused circular beam spot.

Regarding the light-collecting diffraction grating as mentioned above,
For example, IEICE technical research report MW83-88, 47
Detailed information is provided on pages ~54, etc.

(Embodiments) Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 and FIG. 2 show one embodiment of the optical travel reading device of the present invention. As shown in the figure, this optical scanning reading device includes an optical scanning section 10',
Endless belt device 30 as sub-scanning means
, a photomultiplier (photomultiplier tube) 40 as a photodetector, a light condenser 50 connected to the light receiving surface of the photomultiplier 40,
A glass block 60 is provided. First, the optical scanning section 10' will be explained in detail.

This optical scanning section 10' includes an optical waveguide 11 formed on an elongated substrate 16, a pair of crossed or interdigitated electrodes 15 provided at the side ends of this optical waveguide 11, and a pulse-like voltage applied to this electrode pair 15. Drive circuit 1 that applies
7, and a semiconductor laser 18 directly coupled to one end surface 11a of the optical waveguide 11. The optical waveguide 1 is located near the one end surface 11a.
A waveguide lens 19 is formed on the optical waveguide 1, and a condensing diffraction grating 14 having a curve and a chirp is formed on the surface of the optical waveguide 11 at a position near the end surface 11b opposite to the one end surface 11a. .

In this embodiment, as an example, the substrate 16 is
The optical waveguide 11 is formed by using a LiNbO ₃ wafer and providing a Ti diffusion film on the surface of this wafer. In addition, as the substrate 16, other materials such as sapphire, Si
A crystalline substrate made of, for example, may be used. In addition, the optical waveguide 11 is not limited to the above-mentioned Ti diffusion.
Other materials can also be formed on 6 by sputtering, vapor deposition, or the like. Regarding optical waveguides, for example, see “Integrated Optics” edited by T. Tamir.
Optics” (Topics in Applied Physics) No. 7
Volume) Springer Verlag (Springer−
Verlag) (1975); “Optical Integrated Circuits” by Nishihara, Haruna, and Suhara, published by Ohmsha (1985). can also be used. However, this optical waveguide 11 must be formed of a material such as the above-mentioned Ti diffusion film that allows surface acoustic waves to propagate, which will be described later. The optical waveguide may also have a laminated structure of two or more layers.

The waveguide lens 19 in this embodiment is, for example, a proton exchange type waveguide Fresnel lens, but such a waveguide lens 19 has a SiNx film deposited on the surface of the optical waveguide 11, and positive-type electrons are deposited on the surface of the waveguide lens 19. Apply line resist and then
A conductive Au thin film is deposited, a Fresnel lens pattern is drawn with an electron beam, the Au thin film is peeled off and developed, and the resulting resist pattern is ion-etched.
It can be formed by transferring it to a SiNx film, peeling off the resist, and then performing a known proton exchange. Further, the light-condensing diffraction grating 14 can be made by, for example, applying a negative electron beam resist to the surface of the SiNx film after forming the waveguide lens 19, and further depositing an Au conductive thin film thereon, and drawing the diffraction grating pattern with an electron beam. However, after that, it can be formed by performing the steps from peeling off the Au thin film to peeling off the resist described above. Further, the crossed comb-shaped electrode pair 15 is formed by applying a positive electron beam resist to the surface of the optical waveguide 11, for example.
Furthermore, a conductive Au thin film is deposited on top of the thin film, an electrode pattern is drawn with an electron beam, the Au thin film is peeled off and developed, and then a Cr thin film and an Al thin film are deposited, followed by lift-off in an organic solvent. can be formed.

Note that if the substrate 16 and the optical waveguide 11 are made of a piezoelectric material, the electrode pair 15 can generate the surface acoustic wave 12 even if it is installed directly inside the optical waveguide 11 or on the substrate 16. If this is not the case, a piezoelectric thin film made of, for example, ZnO may be formed on a part of the substrate 16 or the optical waveguide 11 by vapor deposition, sputtering, etc., and the electrode pair 15 may be placed there.

The aforementioned semiconductor laser 18 emits a laser beam (radiation beam) 13' from one end surface (light incident end surface) 11a of the optical waveguide 11 into the optical waveguide 11. This radiation beam 13' is transmitted through a waveguide lens 19
The beam 13 is made into a parallel beam 13 by
propagates in the direction of arrow A in the waveguide mode within the optical waveguide 11. Note that the beam 13' is made to enter the optical waveguide 11 via a lens, a coupler prism, a diffraction grating (grating coupler), etc., instead of directly coupling the semiconductor laser 18 to the light incident end face 11a as described above. It's okay. In particular, when a diffraction grating is used here, if it is a condensing diffraction grating formed on the surface of the waveguide, the beam 13' entering the optical waveguide 11 can be made into a parallel beam, and the waveguide lens 19 It can be replaced by However, if the semiconductor laser 18 is directly coupled to the light incident end surface 11a and the waveguide lens 19 is used to convert the radiation beam 13' into a parallel beam as in this embodiment, the optical scanning section 10' can be extremely small and It can be highly reliable. Furthermore, the light source that generates the scanning light is the semiconductor laser 18 mentioned above.
However, other lasers such as gas lasers and solid-state lasers may also be used.

A glass block 60 is provided on the bottom surface 16a of the substrate 16.
are joined. This glass block 60 is
Light reflecting layers 61a and 61b are provided on the surface 60a on the side to be bonded to the substrate 16 and on the surface 60b opposite to this surface 60a, respectively. These light reflecting layers 61a and 61b are made of, for example, vapor-deposited mirrors. And the condensing diffraction grating 14 is
It is formed so that the first-order diffracted light of the guided light 13 is diffracted toward the substrate 16 side, and the semiconductor laser 1 of the substrate 16
An end surface 16c opposite to the end surface 16b on the 8-attachment side is formed obliquely so as to face upward in the figure. Therefore, the diffracted light 13 is totally reflected at the end face 16c and enters the glass block 60. Naturally, the oblique cut angle of the end face 16c is set to an angle that causes the above-mentioned total reflection, and a light reflecting layer 61 is provided in the range on the surface 60a of the glass block 60 where the light 13 is incident.
a is not formed.

The light 13 that has entered the glass block 60 as described above is reflected by two opposing light reflecting layers 61a,
61b, the glass block 6 is repeatedly reflected from the surface 60 from which the light reflecting layer 61b is partially removed.
0 Emitted outside.

When reading a document with the optical scanning reading device having the above structure, the document 31 to be read is transported by the endless belt device 30 in the direction of the arrow Y in FIG. Then, the semiconductor laser 18 emits a laser beam 1.
3', and at the same time, a pulse voltage whose frequency changes continuously is applied to the electrode pair 15 from the drive circuit 17. Electrode pair 15
By applying such a voltage to the surface of the optical waveguide 11, the surface acoustic wave 12 propagates in the direction of arrow B in FIG. The electrode pair 15 is arranged so that the surface acoustic wave 12 travels in a direction intersecting the optical path of the guided light (parallel beam) 13.
Therefore, the guided light 13 travels across the surface acoustic wave 12, but at this time the guided light 13 is deflected by the surface acoustic wave 12 as described above.
Since the above voltage is applied to the electrode pair 15, the frequency of the surface acoustic wave 12 changes continuously, and as a result, the deflection angle of the guided light 13 changes continuously. The guided light 13 thus deflected is diffracted toward the substrate 16 by the condensing diffraction grating 14 having a curve and a chirp, and is guided to the optical waveguide 11.
The light is emitted to the outside, passes through the substrate 16, and enters the glass block 60. As described above, this light 13 is repeatedly reflected between the light reflecting layers 61a and 61b, propagates inside the glass block 60, and then reaches the surface 60.
The light is emitted to the outside of the glass block 60 from b.

At the same time, the guided light 13 is transferred to the condensing diffraction grating 14
As a result, the light is focused to a circular spot P in the space outside the optical waveguide 11. As described above, since the deflection angle of the guided light 13 changes continuously, this beam spot P scans one-dimensionally in the direction of the arrow X in FIG. Therefore, if the original 31 is placed at a position irradiated by this beam spot P and the sub-scan is performed in the direction Y that is substantially perpendicular to the scanning (main scanning) direction X, this original 31 is scanned two-dimensionally by the beam spot P.

As an example, the above manuscript 31 is
The stimulable phosphor sheet 31 is a stimulable phosphor sheet disclosed in Japanese Patent Application No. 56-104645, etc., and this stimulable phosphor sheet 31 is irradiated with radiation that has passed through the subject. Radiographic image information of the subject is accumulated and recorded. This stimulable phosphor sheet 31
is the beam spot P (light 13) as described above.
When the sheet 31 is scanned, stimulated luminescence light 32 carrying accumulated and recorded radiographic image information is emitted from the portion of the sheet 31 that is irradiated with the light 13 (see FIG. 1). This stimulated luminescence light 32 is collected by a condenser 50
The light is focused by the photomultiplier 40
Detected photoelectrically by The output signal (read image signal) S of the photomultiplier 40 is subjected to appropriate image processing and then sent to an image reproducing device (not shown), where it is used for reproducing the radiation image information.

In this optical scanning reading device, since the optical path of the scanning light is folded within the glass block 60 as described above, even if the optical scanning section 10' including the glass block 60 is formed in a small size, the surface acoustic wave
The optical path length from the portion deflected by the arrow 2 to the original document 31 to be read can be set sufficiently long, and a long main scanning width can be ensured.

Note that in order to make the length of the reflected optical path within the glass block 60 longer, and the end surface 16c
Naturally, in order to make the light 13 reflected by the glass block 60 enter the glass block 60 more efficiently, the light 13
glass block 60 at an angle of incidence as small as possible.
It is preferable to set the oblique cut angle of the end face 16c so that the light enters the inside. Of course, the optical path length of the above-mentioned folded optical path must be set so that the light 13 exits from the glass block 60 before converging on the spot P.

In addition, when a long main scanning width is required, multiple optical scanning mechanisms having the structure described above are installed in parallel on the same substrate, and each scanning line from several scanning beams is combined to form a single main scanning line. may be configured.

Next, with reference to FIG. 3, another embodiment of the optical travel reading device of the present invention will be described. In the device of this embodiment, the end surface 16c of the substrate 16 is cut obliquely in the opposite direction to that in the devices shown in FIGS. 1 and 2, and a glass block 60 is bonded thereto. In this case, the oblique cut angle of the end face 16c is set so that the light 13 enters the glass block 60 at an incident angle as small as possible. By doing so, the light (first-order diffracted light) 13 diffracted by the condensing diffraction grating 14 efficiently enters the glass block 60, and the optical path length of the reflected optical path within the glass block 60 is set to be sufficiently long. sell.

In the optical scanning reading device constructed as described above, a folded optical path is also formed within the glass block 60, and the same effects as in the devices shown in FIGS. 1 and 2 can be obtained.

An embodiment formed as a device for reading stimulated luminescence light from a stimulable phosphor sheet has been described above, but the optical scanning reading device of the present invention scans an original with light and reads the reflected light from the original. Alternatively, it is, of course, also possible to form the document image so as to photoelectrically detect transmitted light and read the original image.

Further, the sub-scanning means is not limited to the endless belt device 30, but other known devices such as a rotating drum may be used. Of course, this sub-scanning means may be one that moves the original to be read, or one that moves the optical scanning section along the surface of the original that is placed still. In particular, in the device of the present invention, a simple optical scanning section without mechanically operating parts is used, so that the optical scanning section can be easily moved. Further, the photodetector is not limited to the photomultiplier 40, and other known photodetectors such as a photodiode array may also be used.

Further, the optical scanning reading device of the present invention may be formed by arranging a plurality of optical scanning sections in parallel to scan a plurality of beams of light simultaneously. For example, it is also possible to arrange three optical scanning sections in parallel, and to use them for color original reading by combining filters of different colors such as R, G, and B, or light sources of different emission colors.

(Effects of the Invention) As explained in detail above, the optical scanning reading device of the present invention performs optical scanning using a simple optical scanning unit that does not include mechanically operating parts, so it has excellent durability and vibration resistance. Becomes excellent. Furthermore, the device of the present invention does not require a prism coupler for emitting the guided light out of the optical waveguide or a focusing lens for focusing the scanning light, so it is extremely compact.
Furthermore, adjustment is easy and it can be formed at low cost.

Since the optical scanning reading device of the present invention forms a folded optical path within the glass block, it is possible to arrange the optical scanning section close to the original to be read even when the main scanning width is relatively long. It can be formed into a small size.

Furthermore, since the optical travel reading device of the present invention uses a redundant light-converging diffraction grating in order to emit the guided light out of the optical waveguide and focus it,
Even if there is some damage in this diffraction grating portion, the shape of the focusing spot will not be affected, making it possible to always perform accurate image reading with a beam spot of a predetermined shape.

[Brief explanation of the drawing]

1 and 2 are a schematic perspective view and a side view, respectively, showing one embodiment of the optical travel reading device of the present invention, and FIG. 3 is a side view showing another embodiment of the light travel reading device of the present invention. It is. 10'... Optical scanning section, 11... Optical waveguide, 12
...Surface acoustic wave, 13... Waveguide light, 14... Focusing diffraction grating, 15... Cross-comb electrode pair, 16...
...Substrate, 16a...Bottom surface of substrate, 16b, c...
End face of substrate, 17... Drive circuit, 18... Semiconductor laser, 19... Waveguide lens, 30... Endless belt device, 31... Original to be read, 40... Photo multiplier, 50... Light condenser, 60...
...Glass block, 60a, b... Surface of glass block, 61a, b... Light reflecting layer, P... Beam spot, S... Read image signal.

Claims (1)

[Scope of Claims] 1. An optical waveguide formed of a material through which surface acoustic waves can propagate, a light source that allows light to enter the optical waveguide, and an optical system that converts guided light traveling within the optical waveguide into parallel light. a means for generating a surface acoustic wave in the optical waveguide that propagates in a direction intersecting the optical path of the guided light and deflects the guided light; and a surface acoustic wave whose frequency continuously changes. a driving circuit for driving to generate waves; and a light-converging diffraction grating formed on the surface of the optical waveguide to emit polarized guided light outside the optical waveguide and focus it in a space outside the optical waveguide. , each having a light reflecting layer on both opposing surfaces,
A glass block is bonded to the substrate of the optical waveguide so that the light emitted from the optical waveguide is repeatedly reflected between both surfaces before reaching the focused position, and the focused light is irradiated with the glass block. a sub-scanning means for relatively moving an original to be read placed at a position and the optical waveguide in a direction substantially perpendicular to the scanning direction of the light by the deflection; A phototaxis reading device consisting of a photodetector that photoelectrically detects transmitted light, reflected light, or emitted light. 2. The light-converging diffraction grating is formed to diffract the guided light toward the substrate, and the glass block is bonded to the bottom surface of the substrate of the optical waveguide and faces the end surface of the substrate on the light incident side. The light according to claim 1, wherein the end face is formed obliquely so as to totally reflect the light diffracted by the condensing diffraction grating toward the glass block. Scanning reading device. 3. The light-converging diffraction grating is formed to diffract the guided light toward the substrate, and has an oblique end face opposite to the light incident side end face of the substrate, and the light-concentrating diffraction grating Claim 1 characterized in that glass blocks are bonded together.
Phototactic reading device described in Section 1.