JPS58142313A - Optical scanner using hologram - Google Patents

Abstract

PURPOSE:To perform linear scanning without aberrations by making the incident angles of reference light to a hologram and the incident angle of reconstruction light according to the rotation of a hologram disc different. CONSTITUTION:A hologram disc 3 rotates at a specified speed in the direction of an arrow (a) of a broken line. A laser light source 20 is installed in such prescribed position which is the same position as the position of reference light and where there are no differences from the incident angles of reference light R1-R4 even if the incident angle of reconstruction light (r) in the horizontal direction to holograms changes according to the rotation of the disc 3. Converging spherical waves are used for recording light as object light O and cylindrical waves forming linear luminous fluxes R1-R2, R3-R4 are used as reference light R. The incident angle of the reconstruction luminous flux from the light source 20 in the vertical direction of the hologram 3 changes from the incident angles of the reference light according to the rotation of the hologram 3 and the diffraction angle of the output light from the hologram changes so that the reconstructed image is scanned linearly on the imaging plane.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical scanning device that uses a hologram to deflect a light beam at high speed.

More specifically, the present invention relates to an optical scanning device that is effective for use in a device that records or displays signals or images using optical signals, and that is capable of linear plane scanning. 34h
Figure 1 is a diagram showing the main parts of a conventional optical scanning device using a hologram. (also indicated by a dashed line)
Hologram ax made by exposure from K, 32.33
,,, It is configured so that a VC parallel beam is input and a reproduced image by reproduction light 5 is obtained on the imaging plane 4, which is located behind the hologram S and is a nine-scanning plane. In this device, although the hologram disc moves uniformly on the imaging plane 4 as it rotates 30 times, the problem is that the image is distorted due to arc-shaped scanning as shown in the figure. In addition, since the angles of incidence of the recording light and the reproducing light on the hologram are different at both ends of the hologram, there is astigmatism, etc., and there is a drawback that optical scanning cannot be performed with high resolution.

Here, the present invention attempts to realize an optical scanning device that uses a hologram, has a simple configuration, and devises hologram manufacturing conditions and playback conditions.Therefore, it is an attempt to realize an optical scanning device that has no aberrations and can perform linear scanning with high resolution. It is something to do.

The apparatus according to the present invention maintains the position of the recording light source and the reproduction light source at the same position, and even if the horizontal incident angle of the reproduction light to the hologram changes as the hologram disk rotates,
One of the special points is that a predetermined position where the difference from the incident angle of the recording light (reference light) is even is selected. The vertical incident position on the hologram is changed to make it different from the incident angle of the recording beam (reference beam) during recording, and this difference in incidence angle is used to reproduce the diffraction angle of the output beam as the hologram rotates. There is another feature of the nine points that I change so that I scan the image plane in a straight line.

1/E2 to 4 are main part configuration diagrams showing an example of the device according to the present invention, in which FIG. 2 is a perspective view, FIG. 5 is a plan view, and FIG. 4 is a side view. In these figures, numeral 3 is a hologram disk, and here only one hologram is shown, which rotates (moves) at a constant speed in the direction of the dashed arrow a. Note that here, an example using a transmission type hologram disk is shown.

2o is a laser light source with a small luminous flux. This is the aFi imaging plane. The laser light source 20#i is located at the same position as the recording light (reference light), and the hologram disk 50
It is installed at a predetermined position so that even if the horizontal incident angle of the reproduction light r to the hologram changes with rotation, there is no difference from the incident angle of the recording beams (reference beams) 81 to R4(2).

Note that here, the recording light is a convergent spherical wave with the object light 0,
As the reference light R, linear light beams R1 to R2, R3 to R4
A cylindrical wave is used. However, any shape of object light 0 can be drawn. As the hologram 3 rotates (moves) K, the angle of incidence of the reproduction light beam from the light source 2o in the vertical direction on the hologram 5 changes from the angle of incidence of the reference beam during recording, and the diffraction angle of the output light from this hologram changes. has changed, and the playmate is
It sequentially moves on the imaging plane 4 to points Bx, 82-83, and performs linear plane scanning. □ Here, in FIGS. 2 to 4, optical systems during recording and reproduction are shown by broken lines during recording and solid lines during reproduction, respectively.

First, with reference to FIG. 5, the aberration-free operation, which is one of the features of the present invention, will be explained.

FIG. 3K also shows the optical system with the hologram rotated and moved from the position indicated by the solid line 1 to the position indicated by the broken line H2. Here, the reproduction light r is irradiated to the center of the hologram from the same position as the recording light sources R1' and R2. Now, when the hologram 5 moves from the position indicated by the solid line ■ to the position indicated by the broken line 112 and the reproduction light r irradiates the region C3 of R2, the recording light (reference light) applied to the C region and the hologram R If there is a difference between the angle of incidence θ of the reproduction light r and the angle of incidence θ of the reproduction light r, aberrations (mainly astigmatism) occur. The incident angle θ3 is caused by the rotation of the hologram disk 5. ◇In the device according to the present invention, regardless of the 30 rotations of the hologram disk, θ3−θ
1 Select the distance 2 between the hologram 3 and the reproduction light source 20 so that ◇ The calculation formula for finding this distance 2 is shown below. Assume that the hologram 3 moves from the solid line H□ to the broken line H2. In this state, the reproduction light r illuminates the 03 area of the hologram (R2). Here, due to the incident angle θ3Fi of the reproduction light r on the hologram and the rotation of the hologram disk 50, it is expressed by equation (1).

tanθ3”@1nlletlnθ1(1) However, θ
1: Angle of incidence of the reproduction light r on the hologram as seen from the side (see Figure 4) Interference fringes in the horizontal direction in the 03 area of the hologram (R2). Therefore, if the angle of incidence on the impurity is θ-θ, there will be no aberration caused by the difference between θ3 and θ.

If the distance from the center of the hologram 5 to the C3 area in the H2 state is n, and the radius of the hologram disk is P, then (3)
The formula holds true.

n age p-9 n P-9 tan θIT = T(3) 0) If θ knee is 03 in 2, then equation (4) is obtained.

P・ψ T= ! If we assume that six holograms are installed on the hologram disk 3, then 0≦,≦0.44rad (25.
) S degree, and in this case, Equation < 1.03 = 81nψ 2, so equation (4) can be expressed as equation (5) ◇2÷-'-(S) ano1 Since the aberration is maximum when 9, U P? 4 ■ 2- ・□ (6) t
It can also be expressed as JLn 01 "" 41 m1LX.

Next, the operation for linear plane scanning, which is a feature of the present invention, will be explained in detail with reference to FIG.

In Figure 5, the hologram rotates, and it looks like a real IIH engineer! This figure shows the optical system seen from several planes in a state where it has moved by a distance fK from the dotted line H2. Here, the reproduction light r is irradiated onto one end C2 region of the hologram 3.

In this state, on the condensation surface 4, the light source position f(
x, y). Now, assuming that the rotation angle of the hologram is 9, equations (7) and (8) hold true.

θx=θ1cos p (7
) λ 81nθ2- giftθ'ti -, (a) However,
θ1: Angle of incidence of the second light (reference light) on the C-castle as seen from the side θ1: Angle of incidence of the light (reference light) R in the C□ area θ2: Angle of incidence of the light (reference light) Reference light) Incident angle of R to area C2 viewed from the side θ, -〇' (1+Δθd: Output angle of reproduction light 41: area C
Interference fringe spacing λ of 2: The wavelength of the light reproduced image is 83KIiII on the formation surface 4, so K is:
It suffices if equation (9) holds true.

sin θ-8in (θ1d+Δo d) 1 piece (9) (
7>? (ISL) From the equation (9), the aO equation is obtained.

sinθ2−g1nθIdslIsin(θ1cos
9')-sin(,'a+Δo a)02w arc
1itn (slm(θ1cowψ) −5in(θ1
d+Δθd)+81nθ, d'% all a. In the formula, when x and y are calculated from θ2 and θ1, 1
The formula is obtained.

tan θ − × tan θ m9 (11) Equation 2 7 ” + m In the 55th!I, - is the predetermined position (x + F # z) If a light source for the K reference beam R is installed for recording, and a light source for the reproduction beam R is installed at the same position during reproduction and the hologram is irradiated, the reproduced image on the convergence plane 4 can be reproduced without aberrations and with high resolution. Can perform linear plane scanning.

Figures 6 and 7 show an example of the optical system used for hologram recording in the WAk of this invention.
The figure is an llilI diagram. In this embodiment, the spherical lens 21. By using the cylindrical lens 22 and the cylindrical lens 22, the linear light source R□-R2-R5-R4 in FIG.
has been realized. Note that as the reproduction light r, one with a small beam width is used.

In the above description, a transmission type hologram is used as the hologram, but a reflection type hologram may also be used.

As explained above, by devising the hologram manufacturing conditions and reproduction conditions, the present invention has been able to realize an optical scanning device that has a simple configuration, is free from aberrations, and can perform linear scanning with high resolution.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts of a conventional optical scanning device using a hologram, and FIGS. 2 to 4 are block diagrams of main parts showing an example of a device according to the present invention. Figure 3 is a plan view, Figure 4
The figure is a side view, Figure 5 is a larger explanatory diagram explaining the optical system,
FIGS. 6 and 7 show an example of an optical system for recording a hologram in the present invention, with FIG. 6 being a plan view and FIG. 7 being a side view. 3... Hologram disk, 4... Light source, 21... Spherical lens, 22... Cylindrical lens.

Claims (1)

[Claims] (1) In an optical scanning device using a hologram disk with transmission and reflection, the position of the light source of the recording light (reference light) and the light source of the reproduction light are at the same position, and the position of the light source of the reproduction light is the same as the rotation of the hologram disk. Therefore, even if the horizontal incidence angle of the reproduction light to the hologram changes, the hologram of the recording light (reference light) is selected at a predetermined position so that there is no difference from the incidence angle of the recording light (reference light). The angle of incidence on the hologram is different from the angle of incidence on the hologram of the reproduction light as the hologram disk rotates, and this angular difference is used to change the diffraction angle of the output light from the hologram as the hologram rotates. An optical scanning device using a hologram, characterized in that the reproduced image on the pongee image is scanned in a straight plane without any aberration.