JPS62280827A - Optical scanner - Google Patents

Abstract

PURPOSE:To make the titled scanner high in resolution, small in size and light in weight, unnecessary in adjustment after assembly, and to obtain the durability with high level, by providing a grating coupler, and a waveguide type lens, on an incident side of a thin film type optical waveguide, and an emitting side, respectively, and providing an optical deflecting part between them. CONSTITUTION:A light beam which is emitted as parallel rays from a light source 24 is coupled to an optical waveguide layer 23 through a grating coupler 25 of an incident side, and reaches an image forming surface 31 of a photosensitive body 30 through an optical deflecting part 27, and a waveguide type lens 26 of an emitting side. In such a case, when an RF signal is applied to a transducer 28 of the optical deflecting part 27, a Surface Acoustic Wave SAW is excited by a piezoelectric effect, and a period structure 32 of a refractive index is obtained. Accordingly, the coupled light beam is deflected in the angle direction for satisfying a Bragg condition, jumped up in the direction vertical to the film surface of the optical waveguide layer 23 by the waveguide type lens 26 of the emitting side, and also, a uniform angular velocity interlocking of a deflected light is converted to a uniform speed linear interlocking, and the light is condensed on the image forming surface of the photosensitive body 30.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention Field of Industrial Application 1 The present invention relates to an acousto-optic optical scanner having an integrated high-speed sensor.

``Prior art'' An optical scanner used in laser printers, copiers, etc. includes a rotating polygon mirror that deflects light from a light source, and the light reflected by the rotating polygon mirror is transferred to a photoreceptor, photoreceptor, etc. There is one that is constructed with an fO lens that converts constant angular velocity motion into uniform linear motion and focuses light on the imaging plane (surface) of .

In the case of such an optical scanner, each mechanical part is independent, and a predetermined spacing between each mechanical part is required, which complicates assembly and precise adjustment and increases the size of the device.

In order to solve the above-mentioned drawbacks, a thin film waveguide type optical scanner using the acousto-optic effect shown in FIG. 4 has been proposed.

As is clear from FIG. 4, this optical scanner is
A laser diode 2 that emits guided light is provided at one end of the n-film optical waveguide 1, and a collimator 3 that converts the guided light into parallel light extends from the - end side (light source side) to the other end of the optical waveguide I. 5AW (Sur
face acoustic wave) transducer4. An imaging lens 5 for condensing the guided light is provided.

In FIG. 4, reference numeral 6 denotes a photoreceptor (photoreceptor) placed at a certain distance from the output end of the leading waveguide l.

7 is an imaging plane (surface) of the photoreceptor 6.

Note that the optical waveguide 1 is made of ZnO, LiNbO3, LiTaO
For the imaging lens 5, a thin film lens such as a mode index lens, a geodesic lens, or a Lunebrook lens is used.

Problems to be Solved by 1 Emission 1 In the optical scanner shown in FIG. 4, the above-mentioned thin film lens is used as the imaging lens 5 that focuses the light onto the imaging surface 7'2 of the photoreceptor 6. The locus of the image plane focal point on the image plane 7 is curved.

Such a curvature phenomenon occurs in the optical scanning band (in the direction of the arrow in Fig. 4).
When the optical scanning band is narrow, the effect can be ignored, but when the optical scanning band is wide, the defocus increases in the direction of the arrow in FIG.

Therefore, in the optical scanner shown in FIG. 4, as a countermeasure, the output end face 8 of the leading waveguide 1 is curved, but since the leading waveguide 1 is made of the above-mentioned crystalline material, the technical difficulty in rounding becomes high.

On the other hand, in the thin film type optical waveguide l, although the direction parallel to the film surface is good, the light cannot be focused in the direction perpendicular to the film surface.
When attempting to condense light in both directions on the imaging surface 7, it becomes necessary to interpose a cylindrical lens 8 between the imaging surface 7 and the output end surface 8, and the distance between the lens 9 and its optical path is required. The size of the packaging will increase accordingly.

Furthermore, if the optical scanner shown in Fig. 54 is used for a laser printer, for example, it becomes necessary to interpose an fO lens 10 after the cylindrical lens 9, which also increases the size of the device for the same reason as above. It becomes difficult to adjust the lens system after assembling the device.

In view of the above problems, the present invention can satisfy high resolution, small size and light weight, no need for adjustment after assembly, and high durability! I! The aim is to provide a multilayer optical scanner.

Means for Solving Problems J The optical scanner according to the present invention is a thin-film optical waveguide having one end having a light source as an input end and the other end as an output end. A grating coupler is provided on the input side and a waveguide lens is provided on the output side, and an optical deflection section is provided between the grating coupler and the waveguide lens to achieve the desired purpose. .

r Implementation Example J The following is unreleased 1! An example of the +1 optical scanner will be explained with reference to the drawings.

In FIGS. 1 and 2, 21 is a substrate, and 22 is a thin film type optical waveguide.

The optical waveguide 22 includes ZnO, LiNb0], LiTa
Acousto-optic materials such as 0) are used.

For example, NS, M for the guiding waveguide, and Zn as the optical material.
When O is used, the optical waveguide 22 uses a glass plate or a sapphire plate as the substrate 21, and uses Zr+0 grown as a polycrystal or a tunic crystal with C-axis orientation as the leading wave layer (waveguide II) 23 on the substrate. It is formed on 21F.

Reference numeral 24 denotes a light source consisting of, for example, a semiconductor laser and a collimating lens, and this light source 24 is attached to one end of the optical waveguide 22 via a manting means.

Reference numeral 25 denotes a grating coupler provided on the incident side of the optical waveguide 22, and this grating coupler 25 has a function of coupling a powerful light wave from the light source 24 to the optical waveguide layer 23.

Reference numeral 26 denotes a waveguide lens (imaging lens) provided on the output side of the guide waveguide 22. This waveguide lens 2B is made of, for example, a hologram lens, and is a device 1 for condensing the guided light onto a spatial plane. It has a function of converting the uniform angular velocity motion of the guided light into equicircular motion.

The hologram lens in this case may be either a refractive index modulation type or a relief type.

27 is the grating coupler 2 in the leading waveguide 22
5. A light deflection section provided between the waveguide lenses 26;
This optical deflection unit 27 is mainly composed of a transducer 28, to which an ultrasonic absorber 29 is combined. The transducer 28 has a function of exciting surface acoustic waves, and an ultrasonic absorber Reference numeral 29 has a function of eliminating the shadow 1 caused by reflection from the SA, and a line segment connecting the transducer 28 and the ultrasonic absorber 29 forms a Bragg angle with the optical axis of the optical waveguide 22.

In the figure, 30 is a photoreceptor (photoreceptor) in a laser printer, a copying machine, etc., and 31 is an image forming surface of the photoreceptor 30.

In the embodiments of FIGS. 1 and 2 described in , the first number 124
The light emitted as one line of light is coupled to the optical waveguide layer 23 via the grating 7gukatsuzura 25 on the incident side,
Thereafter, the light passes through the light deflection section 27 and the waveguide lens 26 on the output side, and then reaches the image forming surface 31 of the photoreceptor 30.

At this time, when an RF multiplied signal is applied to the transducer 28 of the optical deflection section 27, the SA trade is excited due to the piezoelectric effect.
The SAW creates a circumferential M structure 32 of refractive index due to the photoelastic effect.

Therefore, the light coupled to the optical waveguide layer 23 via the grating coupler 25 is
The deflected light is deflected in an angular direction that satisfies the Bragg condition, and the deflected light is bounced up by the waveguide lens 26 on the output side in a direction perpendicular to one film surface of the optical waveguide layer 23, and The uniform angular velocity motion of the polarized light is converted into isophartic line interlocking, and the light is focused on the imaging surface 31 of the photoreceptor 30.

In this way, the light passing through the optical waveguide layer 23 is simultaneously focused in a direction parallel to and perpendicular to the waveguide layer 23, and is focused into a substantially spot shape on the image forming surface 31.

As mentioned above, the ultrasonic absorber 29 eliminates the influence of SA- reflection, but the SAW reflection surface is rough <L,
When taking measures such as scattering the reflected waves of the SAW, the ultrasonic absorber 29 can be omitted.

Next, a more specific example of the above-mentioned embodiment will be explained using a design example for a laser printer.

The leading wave layer 23 is C-axis oriented ZnO deposited on the glass substrate 21, and the SAW propagation velocity v5,
RF multiplied signal band ΔD applied to the transducer 28,
The printing width 1p of the printer, the printer printing resolution P, and the printing size PL were set as follows.

Vs = 3.15X103 (m/5ec) Δy =
800 (MHz)! Q9 = 20 (c) P = 10 (dat/mm) Pt = 8 (row/1 nch) With these condition settings, the number of horizontal scanning points of the optical scanner N, the width of the collimated light beam in the + row, 1dat
The +1) time it takes to write and the scrolling speed V are respectively as shown in -C.

N = lp X P = 2000 (dat) W = N X
Vs / Δp = 7.9 (mta) t = W / v
, =2.5(psec)v = 1/(PX t
XN)=2(CI/5EIC)Thus, printing speed V=
283 (rows/min), the laser print becomes 11 digits, and the RF multiplied signal 11 applied to the transducer 28
By setting Δ0 to an appropriate value yJ, the printing speed can be further increased.

Next, another embodiment of the non-issue 151 will be described with reference to FIG.

The basic configuration of the optical scanner shown in FIG. 3 is as shown in FIG.
Although it is the same as that in FIG. 2, a laser diode array is used as the light source 24, which includes a plurality of laser diodes (1±4 in the figure).

Therefore, the optical scanner in FIG. 3 is equivalent to four optical scanners in FIGS. 1 and 2 arranged in parallel.

In the optical scanner of FIG. 3, the SAW from the transducer 28! ! , it is necessary to determine the delay of the signal that modulates each laser diode according to the extended opening time.

When the design conditions of such an optical scanner are the same as those in FIGS. 1 and 2, the horizontal scanning point fil of the optical scanner is
(t, width of the collimated light beam W, l d
The time t required to write at and the scroll speed V are as follows.

N books = sentence ρXP/4 = 500 (dat) W = NzX
Vs /Δy = 1.97(+u)t =W /
vS=0.83(μ5ec)v=1/(PX
't

In this embodiment, by controlling the temperature of the entire optical scanner, fluctuations in the oscillation wavelength of the laser diode and deterioration of the characteristics of the waveguide lens are suppressed.

As explained above, according to the present invention, a high-speed, high-resolution optical scanner can be constructed in a small, light, and inexpensive manner using a thin l112 type branch, and moreover, it can be constructed with a special lens system. Since I don't think it's a ghost, I'm worried about the adjustment after Group)'Z,
Its integrated structure provides a high degree of durability.

[Brief explanation of the drawing]

Figure 1 is a plan view clearly showing one embodiment of the optical scanner of the present invention, Figure 2 is a side view of the same as above, Figure 3 is a plan view clearly showing another embodiment of the optical scanner, and Figure 4 is a conventional optical scanner. FIG. 3 is a plan view clearly showing the scanner. 21... 11 substrate 22... Optical waveguide 23... Leading wave layer (waveguide film) 2411 - Reference light 1≦1 No. 25 - Grating coupler 2611 - Bone waveguide lens 27... Light deflection section 28. Work - Transducer 29 Work... Trend RF wave absorber 30... Old photoreceptor... Imaging surface 32... Periodic structure agent For patent attorney Yoshio Saito If Figure 3 Figure 48

Claims (7)

[Claims] (1) In a thin-film optical waveguide in which one end with a light source is an input end and the other end is an output end, a grating coupler is installed on the input side of the thin-film optical waveguide, and a waveguide lens is installed on the output side of the thin-film optical waveguide. An optical scanner characterized in that an optical deflection section is provided between the grating coupler and the waveguide lens. (2) The thin film optical waveguide is made of ZnO, LiNbO_3, L
The optical scanner according to claim 1, having an optical waveguide layer made of an acousto-optic material such as iTaO_3. (3) Claim 1 in which the light source is a semiconductor laser
Optical scanner as described in section. (4) The optical scanner according to claim 1, wherein the grating coupler has a function of coupling light waves from the light source to the optical waveguide. (5) The light according to claim 1, wherein the waveguide lens has the function of focusing the guided light on a spatial plane and the function of converting the constant angular velocity motion of the guided light into uniform linear motion. scanner. (6) The optical scanner according to claim 1, wherein the optical deflection section has a function of exciting surface acoustic waves. (7) The optical scanner according to claim 1 or 5, wherein the waveguide lens is a hologram lens.