KR940006608B1 - Hologram-making method - Google Patents

Abstract

Preventing a moving phenomenon of fringe and increasing a modulation of the fringe for recording to hologram, the method provides a high efficient hologram. The transmitting type hologram comprises: a shutter (2) for cutting off and transmitting the laser; a beam spliter (3); reflix mirrors (4,5); beam expanders (6,7); and a hologram plate (10). Here this method uses a blocking film (S) at a part of plate, after manufacturing a hologram (26), detects a fringe (30) generated from interference phenomenon between a generated object light and a transmitted object light, openes a shutter according to a switching driving sec. (20) and a shutter driving sec. (21), and irradeates the object light and the reference light.

Description

How to make hologram

1 is a manufacturing diagram of a conventional transmission hologram.

2 is a manufacturing diagram of a transmission hologram of the present invention.

3 is an explanatory diagram showing generation and detection of an interference fringe by a monitor hologram according to the present invention.

4 is a manufacturing diagram of the reflective hologram according to the present invention.

* Explanation of symbols for the main parts of the drawings

1: laser 2: shutter

3: beam splitter 4, 5: reflector

6, 7: beam extender 10: hologram plate

11: object light 12: reference light

12 ': transmitted reference light 13: interference pattern

14 optical sensor 15 amplifier

16: analog / digital converter 17: central processing unit

18: display unit 19: input unit

20: switch driver 21: shutter driver

22, 23: partial reflector 24: laser beam for the monitor

25: right angle prism 26: monitoring hologram

27: transmitted object light 28: reproduced object light

29 screen 30 interference pattern for monitor

d: Spacing between interference fringes a: Detection part of the optical sensor

P: One point L, L ₁ , L ₂ on the hologram plate: laser light

L ₁ ', L ₂ ': Laser light for monitor S: Blocking film

The present invention relates to a hologram (Hologram) manufacturing method, in particular to prevent the movement of the interference pattern during the production of holograms to increase the modulation (Modulation) of the interference pattern to be recorded in the hologram to make a hologram suitable to obtain a high efficiency hologram It is about a method.

As shown in FIG. 1, a conventional transmission hologram includes a laser 1 for a light source, a shutter 2 for blocking or transmitting a laser beam, and a beam splitter for dividing the laser beam into two. 3) a reflector (4) (5) for bending the laser light in a desired direction, a beam expander (6) (7) and a lens (8) to enlarge the diameter of the laser light so as to project a desired area; 9, a hologram plate 10 capable of recording a hologram, an object light 11 and a reference light incident on the hologram plate 10 through the lenses 8 and 9; 12) and an interference fringe 13 which is incident on the hologram plate 10 and is formed on the hologram plate 10 by the interference phenomenon.

In the conventional structure configured as described above, when the light L emitted from the laser 1 for the light source passes through the shutter 2, the light L may pass or be blocked depending on the operating position of the shutter 2.

That is, when the shutter 2 is in the on state, the laser light L is divided into two lights L1 and L2 through the beam splitter 3, and the lights L1 and L2 are If necessary, through the respective reflectors 4, 5 and the beam extenders 6, 7 and the lenses 8, 9, the hologram plates as the object light 11 and the reference light 12, respectively. Enters 10).

Therefore, in some cases, the lenses 8 and 9 may be omitted, and light transmitted through or scattered by an object to record an image instead of the lens 9 may be used as the object light 11.

The object light 11 and the reference light 12 form an optical interference pattern 13 which is a series of dark and dark portions on the hologram plate 10 by indirect phenomenon, and the interference pattern 13 (Fringe) forms the hologram. The plate 10 is recorded.

The process of recording the interference pattern 13 into the hologram plate 10 is that a point P on the hologram plate 10 is an object light (when the shutter 2 is turned on, that is, when the laser light 1 passes). 11) and the reference light 12, and the indirect phenomenon of the reference light 11 and the object light 12 causes the point P to have a constant intensity I (p).

That is, if the time that the laser is turned on is T, the point P receives the energy of E = I (p) .T-(1), and the potential caused by the energy is developed through the development process. Since the interference fringes 13 recorded in 10) usually have an interval of 1 m or less, direct observation is difficult.

In this conventional hologram manufacturing method, the path from the laser 1 divided into two by the beam splitter 3 and then incident to each point P is referred to as (l1), (l2). If the wavelength of (1) is λ, the path difference δ between the two lights is δ = l1-l2 and the phase difference Δ ) to be.

The amount of light incident on the point P on the hologram phase difference 10 at any one moment is determined by the phase difference according to Equation (2).

△ When n = 2nπ (n is an integer), I (p) = Imax has the maximum value Imax and △ I (p) = Imin when = (2n + 1) π Since it becomes zero, the amount of light Ip incident on the point P during the exposure time T must be maintained accurately.

However, during the exposure time, the laser light L1 and L2 are caused by minute movements of air, each of the reflectors 4 and 5 and the beam extenders 6 and 7 and the lenses 8 and 9. The paths l1 and l2 between the object light 11 and the reference light 12 and incident on the point P are respectively different values l1. l1 ', l2 l2 '), The amount of light incident on point P can be changed from I (p) to I (p '). Changes to I (p)

Here, the change in the amount of light incident on the point P during the exposure time means that the interference fringe 13 moves during the exposure time. When this phenomenon occurs, the quality of the hologram finally obtained is very poor.

In order to prevent this phenomenon, minimize the exposure time (T) to eliminate external disturbance during the exposure time, but in some cases exposure time can range from a few seconds to several minutes, so position control for each optical element through which the laser beam passes Unless the quality of the hologram is deteriorated unless there is a problem.

In order to solve this problem, the present invention manufactures a monitoring hologram on a part of the holographic recording plate, and detects the change in the amount of interference between the reproduced object light and the transmitted object light and is recorded on the hologram recording plate. Invented a hologram manufacturing method that can produce a hologram by exposing only when there is no change in the interference fringe, described with reference to the accompanying drawings as follows.

2 is a manufacturing diagram of a transmission hologram of the present invention, as shown therein, a light source laser 1, a shutter 2 for blocking or transmitting a laser beam, and a beam splitter for dividing the laser beam into two. (3), reflectors (4) and (5) for deflecting the desired direction of the laser beam, beam extenders (6) and (7) for widening the diameter of the laser beam to illuminate a desired area, and a hologram can be recorded. The hologram plate 10, the object light 11 and the reference light 12 incident on the hologram plate 10 by the beam extenders 6, 7, and the hologram plate 10. And a transmissive hologram composed of an interference fringe 13 formed on the hologram plate 10 by indirect development, comprising: an optical sensor 14 and an amplifier 15 for amplifying the output of the optical sensor 14; Converting the analog signal output from the heavy aerator 15 to a digital signal An analog-to-digital converter 16, a central processing unit 17 for receiving and processing the digital signal, and a switching driver 20 for generating a signal necessary for operating the shutter 2 by the central processing unit 17. And the shutter driver 21 for operating the shutter 2 in a blocked or light-transmitted state by the switching driver 20, and a part of the laser 1 light is reflected by the monitor laser beam 24. Lasers for the monitor divided by the partial reflectors 22 and 23 combined through the same path as the laser beam L of the light beam and the beam splitter 3 by the partial reflectors 22 and 23. A monitoring hologram 26 in which light L1, L2, L1 ', L2' is irradiated only to a partial region of the hologram plate 10, and the analog / digital by means of the central processing unit 17; The numerical value inputted to the converter 16 is displayed, a numerical value is input in advance, and processed by a program. Constitutes a display unit 8 and the input unit (9) for to control a shutter (2).

The operation and effect of the present invention configured as described above will be described with reference to the generation and detection of the interference fringe by the monitor holograms shown in FIGS. 3 and 4 and the manufacturing of the reflective hologram.

In the method of manufacturing a transmission hologram according to the present invention, a part of the hologram plate 10 is exposed to produce a monitoring hologram 26, and the hologram plate 10 including the monitoring hologram 26 is an object light 11. And exposing to the reference light 12 to produce a hologram.

First, as a step of manufacturing the monitoring hologram, the laser light L emitted from the laser 1 is divided into two laser lights L1 and L2 through the beam splitter 3, respectively, which are respectively reflecting mirrors 4, The object light 11 and the reference light 12 enter the hologram plate 10 via the beam extender 6 and 7.

At this time, the monitor laser lights L1 'and L2' are blocked.

In addition, in the hologram plate 10, except that the monitoring hologram 26 is used, a blocking film S that blocks transmission of light is prevented from being exposed to light. Through the process, the hologram plate 10 on which the monitoring hologram 26 is formed is prepared.

In the process of manufacturing the hologram, as shown in FIG. 3, the hologram plate 10 is fixed at the same position as in the previous step, the object light 11 and the reference light 12 are incident and the interference pattern 13 caused by the interference of the two laser light is ) Is the process of recording.

At this time, the blocking film S is removed, and the object light 11 and the reference light 12 irradiated to the monitoring hologram 26 are the laser beams L1 ′, L2 ′ for the monitor, respectively, and the beam extender 6, ( 7) to be enlarged by the incident.

Accordingly, the reference light 12 incident on the area of the monitoring hologram 26 generates the object light 28 reproduced with the object light 11 and the wavefront by the hologram principle.

The reproduced object light 28 causes interference with the transmitted object light 27 so that the two light lights 28 and 27 interfere with each other, thereby forming a monitor interference pattern 30.

In other words, if the screen 29 is placed in this position, a series of dark and dark light distributions can be observed. In this case, if the size of the black or dark portions is d, the positions of the partial reflectors 22 and 23 are fine. By adjusting the length d can be made sufficiently larger than the size of the optical sensor 14, the optical sensor 14 receives a constant amount of light (Io).

Here, the change in the amount of light sensed by the optical sensor 14, that is, the change of the interference fringe 30 for the monitor coincides with the change of the interference fringe 13 to be recorded on the hologram plate 10.

The reason is that the path from each laser beam L1, L1 ', L2, L2' through the beam splitter 3 to the beam extender 6, 7 passes. Because they are almost identical, they are equally affected by external disturbances.

Accordingly, the optical sensor 14 actually detects the change of the monitor interference fringe 30 representing the change of the interference fringe 13 which is very small and difficult to detect, and thus actually records the interference recorded on the hologram plate 10. Used to control exposure so that movement of the pattern 13 is minimized.

The method is as follows:

To produce a hologram without moving the interference fringe 13, the shutter 2 only at the moment when the interference fringe 13 is fixed, that is, at the moment when the amount of light detected by the optical sensor 14 maintains the initial value Io. Open to the on position.

Since Io is an analog value, a method of exposing and opening the shutter 2 only when entering a certain range is usually used.

That is, if the amount of light of the interference fringe 13 felt by the point P of the hologram plate 10 is I (p), the change of Io, which represents the change of I (p), is calculated in advance. The shutter 2 is in the on position only when it is in the range ≤Io≤Io + ΔI --- (4).

Thereafter, the signal sensed by the optical sensor 14 is amplified by the amplifier 15, and this value is input to the central processing unit 17 by the analog / digital converter 16, and this value is input to the central processing unit. Compared to the value? I input to the input unit 19 by (17), the shutter 2 is opened only for a predetermined time T1 in which the detection value of the optical sensor 14 does not deviate from equation (4). The shutter 2 is turned off at the moment when it is turned on and out of range.

Again when Io is in the range of equation (4), the shutter 3 is exposed for T2 in the on position, thus exposing it while being T1 + T2 --- T and the shutter 2 is in the off state. It becomes

Another control method may display the Io value on the display unit 18 and control the shutter 2 through the input unit 19.

On the other hand, the present invention can be used in the manufacture of the reflective hologram as shown in Figure 4, the process is that the two object light 11 and the reference light 12 is incident in different directions of the hologram plate 10 Same as except.

Therefore, the present invention can be used for producing all kinds of holograms regardless of the type of hologram recording medium.

As described in detail above, when the hologram is manufactured, the effect of phase shift of the interference fringe generated during hologram recording can be eliminated, so that a high-efficiency hologram can be produced and exposed regardless of the cause of the interference fringe change. As a result, it is possible to manufacture a hologram that requires long exposure without affecting the low power laser and the surrounding environment, and to be applied to the manufacture of the hologram element for HLSU and the hologram element for BCR.

Claims (3)

Shutter 2 for blocking and transmitting the light L with the laser 1, Beam splitter 3 for dividing the light L into two L1, L2, and the light L1 and L2 are incident to the object light 11 and the reference light 12 through the reflectors 4, 5 and the beam extenders 6, 7, respectively, as necessary, so that the interference fringe 13 In the transmission hologram composed of a hologram plate 10 is formed, the monitoring hologram 26 is prepared in advance by using a blocking film (S) in a part of the hologram plate 10, and when the hologram is manufactured When the object light 28 reproduced by the object light 11 and the reference light 12 incident to the area and the transmitted object light 27 are generated, interference caused by the two lights 27 and 28 is generated. Check the monitor interference pattern 30 to open the shutter 2 in accordance with the switching driver 20 and the shutter driver 21 by the central processing unit 17 only when there is no movement of the interference pattern 13. By irradiating the object light (11) and the reference light (12). The amount of light detected by the interference fringe 13 in advance from the display unit 18 and the input unit 19 in the central processing unit 17 via the amplifier 15 and the analog-to-digital converter 16. And the shutter (2) is turned on only when the range of Io-ΔI≤Io≤Io + ΔI is satisfied in comparison with a specified amount of light. The method of claim 1, wherein the laser (1) light is made using the partial reflector (22), (23) and the right angle prism (25) to produce a monitor laser beam (24), even when the shutter (2) is off. Hologram manufacturing method characterized in that the monitoring the amount of light distribution of the interference fringe 30 for monitoring by the hologram (26).