KR20140027813A - Holographic recording apparatus and method - Google Patents

Abstract

Disclosed is a hologram recording apparatus which comprises: a stage unit which holds a hologram recording medium and is able to drive; a hologram recording optical system which has a light source unit for emitting a coherent light, separates a beam emitted from the light source unit into a reference beam and a signal beam, modulates the signal beam, and irradiates the modulated signal beam and the reference beam onto the hologram recording medium; a real-time vibration detection system which detects vibrations of the stage unit; a vibration signal processing unit which generates a light source control signal by processing the vibration detected from the real-time vibration detection system as a signal; and a control unit which controls the light source unit according to the light source control signal generated from the vibration signal processing unit. [Reference numerals] (100) Light source unit; (200) Signal beam optical system; (300) Reference beam optical system; (400) Stage unit; (500) Driving unit; (600) Real-time vibration detection system; (700) Vibration signal processing unit; (800) Damping system; (900) Control unit

Description

Holographic recording apparatus and method

The present disclosure relates to a high speed hologram recording apparatus and method considering vibration reduction.

Hologram technology is a technique that can reproduce a signal as a stereoscopic image by recording interference fringes between a signal beam containing a signal and a reference beam. Hologram technology can be used in various fields such as recording and reproduction of stereoscopic images, prevention of forgery and verification of authenticity, and recording and reproduction of digital data. In addition, microhologram technology for recording three-dimensional images on a two-dimensional plane by recording fine interference fringes on a pixel-by-pixel basis on a photosensitive recording film of a flat plate shape has been commercialized.

In general, recording of a hologram divides a beam emitted from a light source to produce a signal beam and a reference beam, modulates the signal beam according to image information, and then modulates the interference fringes of the modulated signal beam and the reference beam on the hologram recording medium. It is carried out in a manner to form. The modulation of the signal beam is performed in units of Hogel (hologram pixels) by the spatial light modulator, and therefore, a stage for holding the hologram recording medium is driven to change the recording position on the hologram recording medium in order to record the large area hologram.

For high-speed hologram recording using continuous wave (CW) lasers, the stage holding the hologram recording medium repeatedly performs the move-stop process. As the stage repeatedly performs the acceleration and deceleration, high-quality holograms are produced. High precision vibration control is required for recording.

The present disclosure provides a hologram recording apparatus and method for vibration reduced hologram recording.

According to one type of holographic recording apparatus, a holographic recording medium holds a hologram recording medium and is provided to be driven; The light source unit emits coherent light, and splits the beam emitted from the light source into a reference beam and a signal beam to modulate the signal beam, and modulates the modulated signal beam and the reference beam into the hologram. A hologram recording optical system irradiating the recording medium; A real-time vibration detection system for detecting the vibration of the stage unit; A vibration signal processing unit for generating a light source control signal by processing the vibration sensed by the real-time vibration detection system; And a controller configured to control the light source unit according to the light source control signal generated by the vibration signal processing unit.

The vibration signal processing unit may generate a firing signal synchronized with a timing at which vibration is relatively low by tracking the vibration signal over time.

The real-time vibration detection system comprises a mirror disposed on the stage; A laser light source for irradiating light to the mirror; It may include; an optical sensor for sensing the light reflected from the mirror.

The vibration signal processing unit may extract the vibration pattern by analyzing the speckle pattern reflected from the mirror.

The light source unit may include a continuous wave laser.

The stage unit may include a damping system that absorbs vibration.

The damping system may be composed of a vibration absorbing member disposed on one surface of the stage, and the vibration absorbing member may be formed of a silicone sealant.

The damping system may be constituted by a rubber plate supporting the hologram recording medium.

The hologram recording optical system separates a beam emitted from the light source into a reference beam and a signal beam, and modulates the separated signal beam according to holographic pixel information to irradiate the holographic recording medium. ; And a reference beam optical system for irradiating the reference beam to a position on the hologram recording medium to which the signal beam is irradiated.

The signal beam optical system includes: a beam separation extension unit for dividing a beam from the light source into a reference beam and a signal beam, and extending a beam diameter of the signal beam; A spatial light modulator for modulating the signal beam according to hologram pixel information; And an objective lens unit focusing the signal beam modulated by the spatial light modulator onto the hologram recording medium.

The beam separation extension may include a first beam splitter for splitting a beam from the light source into a reference beam and a signal beam, and a pair of relay lenses disposed on an optical path of the signal beam.

The spatial light modulator may be a reflective spatial light modulator, in which case the light from the beam separation extension between the beam separation extension and the objective lens unit is directed to the spatial light modulator, and the spatial light modulator A second beam splitter may be further disposed to direct the light modulated by the object lens unit.

The reference light optical system may include an objective lens for focusing the reference light on the hologram recording medium and at least one mirror for adjusting an optical path.

In addition, the hologram recording method according to one type includes a vibration sensing step of detecting in real time the vibration generated when the stage holding the hologram recording medium is driven; A control signal generation step of generating a control signal for driving a light source unit which emits light for hologram recording by signal processing the vibration sensed in the vibration detection step; And driving the light source according to the control signal.

The control signal generating step may generate a firing signal synchronized with a timing at which vibration is relatively low by tracking the vibration signal over time.

The vibration sensing step may include disposing a mirror on the stage and irradiating a laser beam to the mirror; And detecting the light reflected from the mirror with an optical sensor.

The generating of the control signal may include extracting a vibration pattern by analyzing a speckle pattern reflected from the mirror.

The light source unit may include a continuous wave laser.

The above-described hologram recording apparatus and method generate a firing signal by tracking vibration in real time, and control the light source using the hologram recording apparatus, so that high speed hologram recording can be performed with the vibration minimized.

In addition, by applying a damping system to the stage holding the hologram recording medium, high-speed hologram recording can be performed in a state where vibration is minimized.

1 is a block diagram showing a schematic configuration of a hologram recording device according to an embodiment.
FIG. 2 shows an exemplary structure of a real time vibration sensing system employed in the hologram recording device of FIG. 1.
FIG. 3 exemplarily shows generating a firing signal for controlling a light source from the vibration tracking pattern processed in the vibration signal processing unit employed in the hologram recording device of FIG. 1.
4 shows a schematic configuration of a hologram recording device according to another embodiment.
5 shows a schematic configuration of a hologram recording device according to another embodiment.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following drawings, like reference numerals refer to like elements, and the size of each element in the drawings may be exaggerated for clarity and convenience of explanation.

FIG. 1 is a block diagram showing a schematic configuration of a hologram recording apparatus 1000 according to an embodiment, and FIG. 2 is an exemplary structure of a real time vibration sensing system 600 employed in the hologram recording apparatus 1000 of FIG. 3 shows an example of generating a lighting signal for controlling a light source from a vibration tracking pattern processed by a vibration signal processing unit employed in the hologram recording apparatus 1000 of FIG. 1.

In the hologram recording method of the embodiment, in the hologram recording, a vibration sensing step of detecting in real time a vibration generated when the stage holding the hologram recording medium is driven, and a signal processing the vibration detected in the vibration detection step, the hologram And a control signal generating step of generating a control signal for driving a light source unit for emitting light for recording and driving the light source unit according to the control signal; to perform hologram recording in a state of vibrating control with high precision. It is.

The illustrated hologram recording apparatus 1000 is an exemplary structure for implementing such a method. The hologram recording apparatus 1000 holds a hologram recording medium M, is provided with a stage unit 400 to be driven, and a light source unit 100 for emitting coherent light. A hologram for dividing a beam emitted from a light source into a reference beam and a signal beam to modulate the signal beam, and irradiating the modulated signal beam and the reference beam to the hologram recording medium M Real-time vibration detection system 600 for detecting the vibration of the recording optical system, the stage unit, a vibration signal processing unit 700 and a vibration signal processing unit for generating a light source control signal by signal processing the vibration detected in the real-time vibration detection system 600 And a controller 900 for controlling the light source unit 100 according to the light source control signal generated at 700.

The hologram recording optical system separates the beam emitted from the light source unit into a reference beam and a signal beam, modulates the separated signal beam according to the hologram pixel information, and irradiates the hologram recording medium M onto the signal. The beam optical system 200 and the reference beam optical system 300 irradiating the reference beam to a position on the hologram recording medium to which the signal beam is irradiated.

The hologram recording optical system divides the beam emitted from the light source unit to form a signal beam and a reference beam, modulates the signal beam according to image information, and then forms an interference fringe of the modulated signal beam and the reference beam on the hologram recording medium. Is performed. At this time, the modulation of the signal beam is performed in units of Hogel (hologram pixels). For example, the first beamgel modulates the signal beam according to the information and references the signal beam modulated at a corresponding position on the hologram recording medium M. Record the interference fringes of the beam. Next, the hologram recording medium M is moved to the second Hogel position, and the interference fringe between the signal beam and the reference beam modulated according to the second Hogel information is recorded at the corresponding position. As such, the stage portion 400 holding the hologram recording medium M is driven by the drive portion 500 to change the recording position on the hologram recording medium M, and in this process, vibration occurs. In addition, for high speed hologram recording using a continuous wave (CW) laser, the stage unit 400 holding the hologram recording medium M repeatedly performs a move-stop process, and the stage unit 400 As acceleration and deceleration are repeatedly performed, high precision vibration control is required to record high quality holograms.

In this embodiment, for this purpose, a vibration signal for generating a light source control signal by signal processing the vibration sensed by the real-time vibration detection system 600 and the real-time vibration detection system 600 for detecting the vibration of the stage unit 400 in real time The processing unit 700 is employed in the hologram recording apparatus 1000. For example, the vibration signal processing unit 700 tracks the vibration signal according to time, thereby generating a firing signal synchronized with a timing at which vibration is relatively small, and controlling the light source unit 100. Can be delivered to.

Referring to FIG. 2, the real-time vibration detection system 600 detects the light reflected from the mirror 610 disposed on the stage, a laser light source 620 that irradiates light onto the mirror 610, and the mirror 610. It may be configured to include an optical sensor 630.

The mirror 610 may be a mirror polished to form a speckle pattern, and may be formed of, for example, a polysilicon material. The laser light source 620 may be, for example, a laser that outputs a red laser. As the optical sensor 630, various optical sensing elements such as a photo diode may be used.

The vibration signal processing unit 700 may extract the vibration pattern by analyzing the speckle pattern reflected from the mirror 620 and sensed by the optical sensor 630. For example, as shown in FIG. 3, a vibration pattern over time can be tracked and a firing signal synchronized with timings t1 (t2) (t3) with the least vibration can be generated. have. The lighting signal is transmitted to the control unit 900, and the control unit 900 can turn on and off the light source unit 100 in accordance with this signal, thereby performing hologram recording at a timing with little vibration.

In addition, the hologram recording apparatus 1000 may further apply the damping system 800 to the stage unit 400. The vibration of the stage 400 may be reduced by applying a damping system 800 that absorbs or cancels the vibration generated by the driving of the stage 400. The damping system 400 may be configured to additionally install a vibration absorbing member on the stage portion 400 to absorb vibration, or to place the hologram recording medium M on a rubber plate to record holograms. It may be configured to reduce the vibration transmitted to the medium (M). Alternatively, the damping member may be applied to a post (not shown) supporting the stage unit 400. Alternatively, it may be configured as an anti-torque system for canceling the vibration caused by the movement, such as the rotation of the stage 400.

Hereinafter, embodiments of the hologram recording apparatus including a more detailed configuration of the hologram recording optical system will be described.

4 shows a schematic configuration of a hologram recording device 1001 according to another embodiment.

The light source unit 100 may include a laser light source that outputs coherent light. For example, a laser light source that emits a continuous wave (CW) laser or a quasi-CW laser may be used.

The signal beam optical system splits a beam from the light source unit 110 into a reference beam R and a signal beam S, modulates the separated signal beam according to the hologram pixel information, and hologram recording medium. It is an optical system to irradiate. To this end, the signal beam optical system includes a beam separation extension, a phase mask 230, a spatial light modulator 260, and an objective lens unit 270.

The beam splitting extension may include a first beam splitter 220 for splitting a beam from the light source unit 100 into a reference beam and a signal beam, and a beam extension 240 disposed on an optical path of the signal beam.

The first beam splitter 220 may be, for example, a half mirror, and transmits approximately 50% of incident light to be used as a signal beam, and reflects approximately 50% of incident light to be used as a reference beam. Can be. This distribution ratio is exemplary, and the distribution ratio of the signal beam and the reference beam may be set differently. In addition, although the light transmitted through the first beam splitter 220 is shown as a signal beam and the light reflected by the first beam splitter 220 is shown as a reference beam in the drawing, this is exemplary. For example, the optical arrangement of the hologram recording device 1001 may be changed such that the light transmitted through the first beam splitter 220 becomes a reference beam and the light reflected from the first beam splitter 220 becomes a signal beam. .

The beam extension unit 240 may extend the signal beam to a size corresponding to, for example, the effective light modulation area of the spatial light modulator 260, and may include a plurality of optical elements including one or more lenses. The beam extension unit 240 may be configured as a pair of relay lenses as shown, but is not limited thereto.

The phase mask 230 may be provided for shaping the shape of the signal beam and changing the distribution uniformly, and the placement position is not only the position shown but also another position, for example, the position after the beam extension 240. May be changed to.

A filter (not shown) may be further disposed between the light source unit 100 and the first beam splitter 220 as necessary. For example, a band-pass filter for transmitting only light of a specific wavelength band can be further disposed.

The spatial light modulator (SLM) 260 modulates a signal beam according to image information to be formed on the hologram recording medium 150. For example, a liquid crystal on silicon (LCoS) device may be used. .

The spatial light modulator 260 may be a reflective spatial light modulator. In this case, as shown, a second beam splitter 250 may be disposed between the beam extension 240 and the objective lens unit 270. have. The second beam splitter 250 directs the beam such that the light from the beam extension 240 is directed to the spatial light modulator 260, and the light modulated by the spatial light modulator 260 is directed to the objective lens unit 270. Branch.

The second beam splitter 250 may be a transflective mirror that reflects a part of incident light and transmits a part of the incident light. Alternatively, the second beam splitter 250 may be a polarizing beam splitter that transmits or reflects light according to the polarization direction of the incident light. In this case, a polarizing plate (not shown) for transmitting only light in a specific polarization direction may be further disposed on an optical path toward the second beam splitter 250, and the second beam splitter 250 and the spatial light modulator ( A quarter wave plate (not shown) may be further disposed between the 260.

The above description is for the case where the spatial light modulator 260 is a reflective spatial light modulator, but this is exemplary and a transmissive spatial light modulator may be employed. In this case, the second beam splitter 250 is not provided.

The objective lens unit 270 is a Fourier transformation optical system for Fourier transforming the signal beam modulated from the spatial light modulator 260, that is, the signal beam containing the image information and focusing it on the hologram recording medium M. ) Is prepared for the role. Although shown in the drawing as a single lens, this is exemplary and may be configured to further include two or more lenses or other optical elements.

The reference beam optical system transmits the reference light branched from the first beam splitter 220 to the hologram recording medium M, and includes an objective lens 330 and at least one mirror for adjusting the optical path. Although two mirrors 360 and 370 are shown in the figure, this is exemplary and may be modified. For example, the mirrors 360 and 370 can be configured to be rotatable and movable so that the reference beam can be incident on a desired position on the hologram recording medium M at a desired angle of incidence. In particular, the reference beam optics can be configured such that the reference beam is incident at the same position on the hologram recording medium 150 as the signal beam. Further, the reference beam optical system can be configured so that the cross sectional area of the reference beam and the cross sectional area of the signal beam match on the hologram recording medium M. FIG.

In the above-described hologram recording apparatus 1001, the signal beam containing the image information and the reference beam meet on the hologram recording medium M, and the interference fringe generated when the signal beam and the reference beam interfere with each other is recorded on the hologram recording medium M. FIG. .

In order to change the recording position on the hologram recording medium M, the driving unit 500 drives the stage unit 400, and the vibration generated at this time is signal-processed by the vibration signal processing unit 700 to generate a control signal. Transfer to the control unit 900. As described above, the vibration detection is a process of irradiating light to the mirror 610 disposed on the stage unit 400 in the laser light source 620 and detecting light reflected from the mirror 610 in the optical sensor 630. Can be done with.

5 shows a schematic configuration of a hologram recording apparatus 1002 according to another embodiment.

This embodiment differs from the hologram recording apparatus 1001 of FIG. 4 in that it further includes a damping system. The damping system may be configured of, for example, a vibration absorbing member 810 disposed on one surface of the stage unit 400. The vibration absorbing member 810 may be made of, for example, a silicone sealant, and various other materials for absorbing vibration may be used.

In the above, an example of an apparatus for performing hologram recording with reduced vibration by detecting vibration in real time of the stage 400 driven while holding the hologram recording medium M and applying a damping system together will be described. It was. The vibration sensing method may employ various other methods besides a method of sensing reflection and scattering of laser light, as illustrated. In addition, the configuration of the damping system applied to the stage unit 400 may also be variously modified. For example, an anti-talk system may be introduced, or the stage portion or the post supporting the same may be modified into a vibration reduction structure.

Such a hologram recording apparatus and method of the present invention have been described with reference to the embodiments shown in the drawings for clarity, but these are merely exemplary, and those skilled in the art may various modifications and other equivalent implementations therefrom. It will be appreciated that examples are possible. Accordingly, the true scope of the present invention should be determined by the appended claims.

1000, 1001, 1002 ... Hologram recorder 100 ... Light source
200 ... signal beam optics 300 ... reference beam optics
220 first beam splitter 230 phase mask
240 ... beam extension 250 ... second beam splitter
260 ... Spatial Light Modulator 270 ... Objective Unit
320, 340 ... mirror 330 ... objective lens
400 Stage Stage 500 Drive Section
600 ... real-time vibration detection system 610 ... mirror
620 laser light source 630 light sensor
700 ... vibration signal processing unit 800 ... damping system
810 vibration absorbing member 900 control unit

Claims (20)

A stage unit holding the hologram recording medium and provided to be driven;
The light source unit emits coherent light, and separates the beam emitted from the light source unit into a reference beam and a signal beam to modulate the signal beam, and modulates the modulated signal beam and the reference beam into the hologram. A hologram recording optical system irradiating the recording medium;
A real time vibration detection system for detecting vibration of the stage unit;
A vibration signal processing unit for generating a light source control signal by processing the vibration sensed by the real-time vibration detection system;
And a controller for controlling the light source unit according to a light source control signal generated by the vibration signal processing unit. The method of claim 1,
The vibration signal processing unit
A hologram recording device that tracks a vibration signal over time to produce a firing signal synchronized with a timing at which vibration is relatively low. The method of claim 1,
The real-time vibration detection system
A mirror disposed on the stage;
A laser light source for irradiating light to the mirror;
And a photosensor for detecting light reflected from the mirror. The method of claim 3,
The vibration signal processing unit
And a vibration pattern extracted by analyzing the speckle pattern reflected from the mirror. The method of claim 1,
And the light source unit comprises a continuous wave laser. The method of claim 1,
And said stage portion comprises a damping system for absorbing vibrations. The method according to claim 6,
The damping system is a hologram recording device consisting of a vibration absorbing member disposed on one surface of the stage. 8. The method of claim 7,
And the vibration absorbing member is made of a silicone sealant. The method according to claim 6,
And said damping system comprises a rubber plate for supporting said hologram recording medium. 10. The method according to any one of claims 1 to 9,
The hologram recording optical system
A signal beam optical system for dividing the beam emitted from the light source unit into a reference beam and a signal beam, and modulating the separated signal beam according to hologram pixel information to irradiate the hologram recording medium; And
And a reference beam optical system for irradiating the reference beam to a position on the hologram recording medium to which the signal beam is irradiated. 11. The method of claim 10,
The signal beam optical system
A beam separation extension unit for dividing the beam from the light source into a reference beam and a signal beam, and extending a beam diameter of the signal beam;
A spatial light modulator for modulating the signal beam according to hologram pixel information;
And an objective lens unit for focusing the signal beam modulated by the spatial light modulator onto a hologram recording medium. 12. The method of claim 11,
The beam splitter
A first beam splitter for separating the beam from the light source into a reference beam and a signal beam;
And a pair of relay lenses disposed on an optical path of the signal beam. 12. The method of claim 11,
Wherein the spatial light modulator is a reflective spatial light modulator. 14. The method of claim 13,
Between the beam splitter and the objective lens unit
Directing the light from the beam splitter to the spatial light modulator,
And a second beam splitter arranged to direct light modulated by the spatial light modulator to the objective lens unit. 11. The method of claim 10,
The reference light optical system
An objective lens for focusing the reference light onto the hologram recording medium;
And at least one mirror for optical path adjustment. A vibration sensing step of sensing in real time vibration generated as the stage holding the hologram recording medium is driven;
A control signal generation step of generating a control signal for driving a light source unit which emits light for hologram recording by signal processing the vibration sensed in the vibration detection step;
And driving the light source unit according to the control signal. 17. The method of claim 16,
The control signal generation step
A hologram recording method of tracking a vibration signal over time to generate a firing signal synchronized with a timing at which vibration is relatively low. 17. The method of claim 16,
The vibration detection step
Disposing a mirror on the stage and irradiating a laser beam to the mirror;
And detecting the light reflected from the mirror with an optical sensor. 19. The method of claim 18,
The control signal generation step
And extracting a vibration pattern by analyzing the speckle pattern reflected from the mirror. 17. The method of claim 16,
And the light source unit comprises a continuous wave laser.

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