JPS58202424A - Optical beam deflecting device - Google Patents

Abstract

PURPOSE:To reduce a cost of a titled device, by vibrating rockingly one of a pair of mirrors whose mirror faces are opposed to each other, against the other, or vibrating both of them rockingly and complementarily, and constituting so that an optical beam which is made incident between both mirrors can be deflected at a high speed and at a large deflection angle. CONSTITUTION:When an optical beam 1 is made incident from a prescribed direction, between mirror faces M1, M2 of mirrors placed so as to be opposed in parallel to each other, the optical beam 1 is reflected like a zigzag by the mirror faces M1, M2, and is emitted as an optical beam 1O. In this state, when each of mirror faces M1, M2 is silighly vibrated rockingly and complementarily by making their end parts A, B the rocking centers, the emitted beam 1O is deflected periodically at a deflection angle theta around a virtual deflecting center point P by the rocking and complementary slight vibration of the mirror faces M1, M2, and its deflecting period is equal to a complementary vibrating period of the mirror faces M1, M2.

Description

[Detailed description of the invention] The present invention relates to a light beam deflection device.

Conventionally, various types of light beam deflection devices are known in connection with optical printers, document scanning devices, and the like. The optical beam deflection devices of Jl et al. can be roughly divided into three types: those using mechanical methods, those using electro-optic effects, and those using acousto-optic effects. Kowara naturally has advantages and disadvantages, so it is difficult to say whether they are superior or inferior, but they are aimed at ultra-high-speed deflection and dumb deflection. When it comes to leakage and lumps, mechanical methods are superior to other methods in terms of the deflection angle, the number of resolution points, the efficiency of light utilization, and the stability of 1 m degree.

Polarization devices based on the mechanical force method include those that rotate a polygon mirror or prism, and those that vibrate the mirror in an oscillating manner.

A method in which a polygon mirror or the like is rotated has a faster deflection speed, a larger deflection angle, and a larger number of resolution points than a method in which a mirror is oscillated. However, on the other hand, since polygon mirrors and the like have a polyhedral structure, extremely high surface precision is required for the polygon mirrors, and manufacturing costs are high. In addition, since it involves a rotating system, there are problems in terms of mechanical lifespan (i' lJi Note), and non-linearity of deflection due to rotational movement can only be suppressed by an optical system. This also requires a highly accurate and therefore expensive optical system, resulting in an extremely high cost for the entire system.

On the other hand, in a system in which the mirror is oscillated, the surface accuracy of the mirror does not need to be very high, and correction of nonlinearity of deflection is relatively easy. However, when high-speed deflection is to be performed, the conventional situation is that it is not as good as the rotation method due to the possibility of the size of the same angle and the number of resolution points.

Therefore, the present invention is a mirror vibration method.

Furthermore, even during high-speed deflection, a large deflection angle and a high number of resolution points can be obtained, and the structure is extremely simple, does not require much mechanical precision, and can be implemented at low cost. The purpose of this invention is to provide a light beam deflection device.

The present invention will be explained below.

A light beam deflection device according to the present invention includes a pair of mirrors, light beam entrance means, and vibration means.

A pair of mirrors is arranged with their mirror surfaces facing each other.

The light beam incidence means directs the light beam between the pair of mirrors so that the light beam is reflected alternately and in a zigzag pattern by the pair of mirrors.

The vibration means vibrates one of the pair of mirrors in an oscillatory manner in response to another force, or vibrates both mirrors in an oscillatory manner in a complementary manner. The meaning of complementary vibration will be explained later.

Hereinafter, a detailed description will be given with reference to the drawings.

Now, a detailed explanation of the present invention will be given with reference to Figure 1.
In Figure 1, the symbols Ml and M2 indicate the mirror surface of the mirror,
It shows. The mirror surfaces are parallel to each other in the position shown by the solid line.

Now, it is assumed that the mirror surfaces Ml and M2 are stationary, facing each other in parallel in the attitude shown by the solid line, and when a light beam l is made incident between these mirror surfaces from a fixed direction, the light beam l is The light beams are alternately reflected in a zigzag pattern Jl, and the light beam is emitted as a 1° beam.

Next, from this state, each of the mirror surfaces M1 and M2 is slightly vibrated in a complementary manner with the ends A and B as the center of vibration. Each mirror surface M], M2.

The rocking vibrations of the mirror surfaces M1 and Bi are complementary.

This means that the vibration circumferences ml of the mirror surfaces are equal to each other, and the phases of & are lag each other by half a period.

Therefore, when the mirror surface M] takes the positions indicated by the symbols M1', M1'' due to vibration, the mirror surface M2 correspondingly assumes the positions M2', M2''.

When the mirror surfaces Ml and M2 assume the positions Ml' and M2', that is, when they take the positions shown by the chain lines, the light beam 1 incident in a direction is reflected as shown by the chain lines, and becomes the beam 1.
′ and ejects.

The attitude Ml' is inclined by 1/2Δθ with respect to the attitude M1 shown by the solid line, and the attitude M2' of the mirror surface M2 is inclined by 1/2Δ02 with respect to the attitude shown by the solid line.

Therefore, at this time, the direction of reflection of the light beam 1 is slanted toward the mirror surface M1. Furthermore, each time the light is reflected on the mirror surface M2, the direction of reflection changes by Δθ2. Since the vibrations of mirror surface M] and M2 are complementary, -f' of these tl
il is additive. Therefore, in general, the mirror surface Ml
Suppose that the number of reflections by FJ is FJ and the number of reflections by mirror M2 is n2.

What is the name of the direction in the reflected light beam?

1Δθ1+n2Δθ2(1). In Figure 1, rL4 = 1% rL2 = 2
Therefore, beam l. What is the angle between and 1'?

Δθ1+2Δθ2(2) becomes.

Similarly, the mirror surfaces Ml and M2 are in the attitude M1'' shown by the broken line.
, M2'', the light beam 1 is reflected as shown by the broken line, and beam 1'' is emitted. Using the same concept as above, the angle between beams 1° and 1" is:

Δθ1 +2Δθ2(3). Therefore, the 1ttd direction angle θ of the emitted beam due to the complementary vibrations of the mirror surfaces M1 and M2 is.

2ΔU1+4Δθ2(4). That is, due to the oscillating complementary micro-trailing movements of the mirror surfaces M] and M2, the emitted beam 1° is periodically deflected at a deflection angle θ around the virtual deflection center P point, and the deflection period is , are equal to the complementary vibration periods of the mirror surfaces Ml, M2.

Generally, if the number of reflections by the mirror surface M], M2 is nl, rL2 as mentioned above, then the deflection angle is 21'L1 Δ
It will be easily understood that it cannot be given by θ1 '' 2 '' 2 Δ θ2 (5).

In particular, when Δθ1=Δθ2=Δθ, that is, when the mirror surface Ml and M20 angular amplitudes are equal to each other, the deflection angle is.

2 (n1+nl)Δθ (6
). For example, when Δθ1=00, the deflection angle is 2 2 Δθ2 (7), but in the first case, when the mirror surface M is kept stationary and only the mirror surface is oscillated. It is.

The above is the principle of light beam deflection according to the present invention.
Since this deflection method utilizes the rocking vibration of the mirror surface, it may require a high degree of accuracy from the device, as in the case of conventional lift-type deflection.

Moreover, since the configuration is very simple, it can be implemented at low cost.

The deflection angle is basically given by the product of the angular amplitude of the mirror surface and the number of reflections on the vibrating mirror surface, and by increasing both the angular amplitude and the number of reflections, the deflection angle can be increased. Since they can be increased synergistically, large deflection angles can be easily obtained.

For example, with conventional vibration-type deflection mounting, the deflection angle was limited to 4 to 6 degrees at most in the case of high-speed deflection, but with the deflection method of the present invention, even in the case of high-speed deflection, 14~
It is possible to easily achieve the deflection angle of 16 degrees, which is required for a four-speed rotation system.

Regarding the number of resolution points, the magnitude of the deflection angle and the spread of the beam spot are important factors, but the magnitude of the deflection angle can be made sufficiently large as described above. On the other hand, regarding the spread of the beam spot, in the case of the deflection method of the present invention, the beam is simply reflected by the mirror surface.
The principle is the same as in the case of ridge width in the air, and the spread of the beam spot, which is a problem when transmitting a light beam through an electro-optic crystal, does not become a problem in the deflection method of the present invention.

As described above, in the deflection method according to the present invention, the deflection angle is large and the number of resolution points is also large. In addition, the light beam is reflected multiple times between a pair of mirror surfaces tl, and the direction angle is amplified by 1JIll according to the number of reflections, so the vibration of the mirror surface is
1 is sufficient, and therefore high-speed deflection is EJ capable, and even in that case, the deflection angle can be made sufficiently large.

Figure 2 schematically shows only the parts necessary for explaining Embodiment 1 of the present invention.

In the figure, symbol 10t, 11 is a stator, symbol 12 is a support, symbol ]3 is a hole for taking in a light beam, right symbol ]4゜1
5 is pointing at the mirror.

Vibrator 10. The moon has a similar 'M' composition.

No. 11, it is constructed by laminating thin PZT plates through thin film electrodes. In the figure, numerals 101, 102, 111, and 132 are thin plates of PZT. The thin sheet of PZT is one that expands and contracts in a direction perpendicular to the applied electric field, such as a thin sheet of sintered zirconate or ammonium dihydrogen oxide. Since the material cost of PZT is low, the deflection device shown in Figures 1 and 2 can be realized at a lower cost than a system using a rotating polygon mirror or the like.

When an electric field acts on the dough, this PZT thin plate 101# expands or shrinks depending on the direction of the electric field.

For example, when a regular electric field is applied to the thin film electrode of the vibrator IO, an upward electric field acts on the thin plate 101 and a downward electric field acts on the thin plate J02. If it shrinks, thin plate 1
02 extends in the left and right direction. As a result, the camera element 10 is warped upward. Therefore, by applying an alternating current voltage to the electrodes of the vibrator 10, the vibrator 10 can be made to move slowly.

Vibrator 0 and IJ face each other in parallel with one end fixed to a support.

Therefore, by applying voltage to the electrodes of the vibrator 10.11 in an appropriate direction, the vibrator 10.11. ]l can be made to vibrate minutely in an oscillatory and complementary manner. That is, the vibrator 1O111 and a means (not shown) for continuously applying a vibrating voltage constitute a vibrating means.

Mirrors 1 are provided on mutually opposing surfaces of the elbow movers 10 and 11.
4. J5 is formed by, for example, metal thin film deposition (・
Ru.

A hole 13 for taking in the optical beam is bored at a position close to the fixed end of 0 (1A).
The position of the support 12 is fixed in the state shown in Figure 2, and the light beam l is directed through the hole 13 in a unidirectional manner, that is, always from a fixed direction, as shown in the figure. The emitted beam can be periodically deflected by making it enter between the mirrors 14 and 15 through the camera and causing the camera element]0.11 to vibrate minutely in an oscillatory and complementary manner. The period of deflection is the vibration cylinder 1 of the vibrator 10.11.
However, depending on the selection of materials, shapes, etc., the transducer 10.1
The imaging period of 1 is several microseconds to several tens of seconds /j se
Since the length can be shortened to the order of e, extremely high-speed deflection can be realized.

Note that the vibration mode of the vibrator JO 111 can be controlled with a considerable degree of freedom by changing the waveform and magnitude of the applied voltage.

In the above example, we took the case where a pair of opposing mirrors face each other in parallel, but this is not always necessary, and the mirrors may be configured to face in a state other than parallel. It is also possible.

By the way, in recent years, semiconductor lasers have come to be used as light sources for light beams, and as is well known, the luminous flux emitted from semiconductor lasers is a divergent luminous flux, and moreover, the direction of the divergence is are not equidirectional around the optical axis, and therefore the cross-sectional shape of the beam obtained by collimating the above beam is .

Generally, it is an ellipse or an ellipse-like shape that is circular.

In such a case, by using mirrors MLI and ML2 as one-dimensional concave mirrors, such as the cylindrical shape shown in Fig. 4, the length of the beam with the elliptical cross-sectional shape can be increased. By giving a Tokyo tendency in the axial direction, the spot shape on the scanning plane of the deflected beam can be modified to a desired shape. Mirror MLI, M
One of L2 may be a plane mirror.

In FIG. 4, reference numeral 2 indicates mirror MLI, ML2.
shows the plane determined by the optical path of the chief ray of a light beam reflected in a zigzag manner by .

[Brief explanation of drawings]

Figure 1 shows FXI for explaining the principle of the present invention.
The figure is a top view of the bottle showing one embodiment of the present invention.
FIG. 4 is a plan view showing the above-mentioned embodiment ψ(1), and is a diagram for explaining another embodiment of the present invention.

Claims (1)

[Claims] A light beam is directionally incident between the mirrors so that it is alternately reflected in a zigzag pattern by a pair of mirrors arranged with mirror surfaces facing each other and a kneaded mirror. and vibrating means for oscillatingly moving one of the pair of mirrors relative to the other, or vibrating both of the pair of mirrors oscillatingly and complementary. A light beam deflection device that obtains a light deflection angle larger than twice the vibration angle.