JPS62195618A - Optical scanner - Google Patents

Abstract

PURPOSE:To attain linear scanning by arranging plural scanning lenses around the periphery of a rotary disk along the peripheral direction. CONSTITUTION:Many scanning lenses 12 are arranged and fixed on the outer periphery of the rotary disk 1 along the circumference of the disk 1. The lenses 12 are constituted of Fresnel lenses such that the phase distribution (thickness distribution) is vertical to radiant rays extended from the center of the disk 1. Namely, the thickness distribution of the lenses 12 is uniform on the radiant rays. The thickness distribution can be obtained by condensing optical beams in the reaction vertical to the radiant rays. Since the lenses 12 having such a kind of thickness distribution is provided with a function for bending the optical beams only in the direction vertical to the radiant rays without having a function for bending the optical beams in the radial directions of the disk 1, the optical beams made incident upon the lenses 12 in accordance with the rotation of the disk 1 are scanned only in the Y direction.

Description

DETAILED DESCRIPTION OF THE INVENTION Summary of the Invention In an optical scanner in which several scanning lenses are arranged in the circumferential direction near the outer periphery of a rotating disk, the scanning lens has a three-phase distribution that detects radiation extending from the center of the rotating disk. Fresnel curve perpendicular to
It consists of a lens that scans the light beam only in the vertical direction.1. It is characterized by eliminating vibration in the lateral direction.

BACKGROUND OF THE INVENTION TECHNICAL FIELD This invention relates to an optical scanner that has a rotating disk called a hologram disk and scans an incident light beam with a hologram lens disposed around the rotating disk as the rotating disk rotates. .

Conventional technology A schematic configuration of a conventional optical scanner is shown in FIG.

The rotating disk 1 is rotatably supported at its center by a shaft 1O, and is rotationally driven by a rotational drive device. A large number of hologram lenses 2 are arranged along the circumferential direction of the rotating disk 1 at its outer circumference.

The light beam emitted from the laser 3 is converted into parallel light by a lens 4, and further converted into Y by a cylindrical lens 5.
The light is converged in the same direction and converted into flat light, which passes through the hole of the perforated mirror 6 and enters the hologram lens 2 arranged around the one-rotation disk 1 .

As shown in FIGS. 2 and 3, the hologram lens 2 rotates as the disk 1 rotates once.

It makes a circular motion as the locus of its center is indicated by A. As the lens 2 moves circularly, the light beam B is relatively scanned on the lens 2 in an arc. As a result,
The light that has passed through the hologram lens 2 is irradiated onto the object 7 while being scanned in the Y direction.

The light reflected from the object 7 is reflected by the mirror 6, and
The light is received by the line sensor 8.

This provides information on the surface of the object 7. By passing through one hologram lens 2, the light beam is scanned back and forth once in the Y direction. If the object 7 is moving in the X direction, the light beam will be directed to the lens 2 as the disk 1 rotates.
By scanning the object 7 one after another, information on the entire surface of the object 7 can be detected.

However, since the relative scanning locus of the light beam B on the lens 2 draws an arc in the same way as the locus of the center of the lens 2, the light beam emitted from the lens 2 is not only scanned in the Y direction.

It will also be deflected in the X direction. As a result, the scanning locus of the light beam on the object 7 actually became arcuate, and linear scanning in the strict sense of the word was not possible.

SUMMARY OF THE INVENTION OBJECTS OF THE INVENTION It is an object of the invention to provide an optical scanner capable of achieving linear scanning.

Structure and Effects of the Invention The optical scanner according to the present invention is an optical scanner in which several scanning lenses are arranged along the circumferential direction near the outer periphery of a one-rotation disk.

The scanning lens is characterized in that it is constituted by a Fresnel lens in which one phase distribution is perpendicular to the radiation extending from the center of the rotating disk.

The Fresnel lens is formed so that its phase distribution (thickness distribution) is perpendicular to the radiation extending from the center of the rotating disk. In other words, since they are distributed on concentric circles centered on the center of the rotating disk, the light beam incident on this lens as the disk rotates once is scanned only in the direction perpendicular to the radiation (Y direction), The vibration in the X direction is eliminated. Therefore, linear light beam scanning can always be achieved.

Preferably 1. I-A Fresnel lens is manufactured by the following steps.

That is, apply electron beam resist to the substrate.

A predetermined pattern such as a lens is drawn on this resist using an electron beam lithography method, and then the resist is developed. Using the residual film resist pattern on the substrate as a male mold, a female mold is created using an electroforming method. Lenses are manufactured by plastic injection molding using

According to this manufacturing method, the amount of electron beam irradiation and the writing position can be controlled by a computer in the electron beam writing apparatus, so that an ideal lens pattern without aberrations can be obtained.

Since a lens having a flat plate shape and sufficient performance can be obtained with a single lens, it is possible to construct a compact lens system that does not take up much space.

Processes such as polishing can be omitted and manufacturing is easy. Since it can be made by molding plastic, it has excellent productivity. Since the lens shape is determined by computer software, the shape can be freely changed and improved, resulting in high flexibility.

DESCRIPTION OF THE EMBODIMENT FIG. 4 shows an embodiment of the invention. In FIG. 4, parts that are the same as those shown in FIG. 1 are given the same reference numerals.

On the outer periphery of the rotating disk 1, a large number of scanning lenses 12 are arranged and fixed along the circumference.

FIG. 5 shows this rotating disk 1 viewed from above, FIG. 6 shows the lens 12 surrounded by the chain line circle in FIG. 5 viewed from an angle, and FIG. This is the view from the other side. As can be seen from these figures, the scanning lens 12 is composed of a Fresnel lens whose phase distribution (thickness distribution) is perpendicular to the radiation extending from the center of the one-rotation disk 1. There is. That is, the thickness distribution of this Fresnel lens 12 is
It is uniform on the above radiation. This thickness distribution may be such that the light beam is focused in a direction perpendicular to the radiation.

The Fresnel lens 12 having such a thickness distribution does not have any function of bending the light beam in the radial direction of the single-rotation disk 1, but has the function of bending the light beam only in the direction perpendicular to the ray, so it is a double-rotation disk. The light beam incident on the lens 12 as the lens 1 rotates is scanned only in the Y direction.

Since this lens 12 has the function of converting a circular beam into a flat light beam, the cylindrical lens 5 is not necessarily required.

This Fresnel lens 12 is preferably manufactured as follows.

In FIG. 8, the substrate 21. For example, an electron beam resist 22a, such as CM S-EX(R) (
Apply a negative resist (negative resist) uniformly.

An electron beam 23 is irradiated onto this resist 22a by an electron beam drawing device to draw a predetermined lens male pattern (
Figure 8(A)). When this resist 22a is developed, a predetermined lens male pattern 22b remains on the substrate 21 due to the residual film resist (FIG. 8(B)). For electron beam resist, the amount of electron beam irradiation is controlled depending on the location.

The thickness of the film that remains after it is developed depends on the irradiation dose and varies depending on the location. The electron beam drawing device is controlled by a computer, and the electron beam irradiation can be arbitrarily changed for each coordinate position determined on the substrate. Moreover, the change pattern can also be freely determined or selected by software.

Gold is evaporated onto the substrate 21 having the residual film resist 22b of the predetermined lens male pattern thus formed to form the electrode layer 24 (FIG. 8(C)). Further, a plating layer 25 is formed by plating chromium thereon (FIG. 8(D)). Gold electrode layer 24 formed by vapor deposition
The layer 25 is used as an electrode during plating processing, and its thickness is approximately several tens of angstroms.Since the plating layer 25 serves as a female mold for injection molding, it is preferably several microns or more. If the residual film resist 22b and, if necessary, the St substrate 21 are dissolved and removed using an organic solvent, an etching solution, etc., a female mold consisting of the electrode layer 24 and the plating layer 25 remains.

A plastic lens 12 is manufactured by injection molding using the female mold thus formed (Fig. 8 (E).
)).

There are several ways to mold the plastic lens 12 using the female mold 25 (the electrode layer 24 is also square, but the reference numeral 25 is used for convenience). For example, as shown in FIG. 9(A), a mold 25 is placed in a recess 30a of a mold 30 having four parts 30a.

The lens 12 is formed by pouring an ultraviolet curing resin from above and curing this resin by irradiating ultraviolet light.

Also, using two split molds 31 and 32, fill the recess 31a of one of the split molds 31 with a female! ! ! [Contains 225, 9-car type 31.32
Connect them facing each other. Then, resin is injected into the recess 32a of the split Hi 132.

Finally, as an example, two characteristics of the male pattern of a Fresnel lens, that is, the residual resist pattern will be shown.

The male pattern shape of a Fresnel medium lens (Fresnel lens male pattern shape) F (r) is expressed by the following equation.

F(r)=d- (d/2yr) ・([(πr 2)haλf)]
(mod2yr)1d-λ/(n-1) However.

r: distance d from the center of the lens in the direction perpendicular to the above radiation; thickness of the lens λ: wavelength of light incident on the lens; f: focal point of the lens; rate

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the configuration of a conventional optical scanner, and FIGS. 2 and 3 show how a light beam is scanned by the 2-point scanner. (A) is a front view, and (B) is a sectional view. FIG. 4 is a perspective view showing an embodiment of the invention, FIG. 5 is a plan view of a one-rotation disk, FIG. 6 is a perspective view of a scanning lens, and FIG. 7 is a sectional view of the same lens. Figures 8 (A) to (E) are process diagrams for explaining step-by-step the steps of manufacturing a scanning lens, and Figures 9 (A) and (B) are examples of the molding process of the same lens. FIG. ■...Rotating disk. 12...Scanning lens (Fresnel lens). Patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Kenji Ushiku (and one other person) Figure 8 (A) (D) (E) Figure 9 3I Z 5z

Claims (2)

[Claims] (1) In an optical scanner in which a plurality of scanning lenses are arranged circumferentially near the outer periphery of a rotating disk, the scanning lenses are configured so that the phase distribution is perpendicular to the radiation extending from the center of the rotating disk. An optical scanner characterized by comprising a Fresnel lens. (2) The above-mentioned Fresnel lens is a plastic Fresnel lens, in which an electron beam resist is applied onto a substrate, a predetermined pattern such as a lens is drawn on the resist by an electron beam drawing method, and then the resist is developed. A female mold is formed by electroforming using the residual film resist pattern on this substrate as a male mold, and this female mold is used to produce the product. optical scanner.