KR100846860B1 - System and method for recording of objective wave, reference wave and interference pattern in digital holography system - Google Patents

Abstract

The present invention relates to a digital holography recording system and method.

The object light, the reference light and the interference fringe recording system according to the present invention include a laser for generating light using an incoherent light source; A light diffuser for diffusing light generated by the laser; A light splitter dividing the diffused light into object light and reference light; And a holographic recording system using an interferometer structure for effectively removing zero-order diffracted light by having at least one reflector reflecting object light and / or reference light, comprising: a first CCD for recording object light; And a second CCD for recording the interference fringes of the object light and the reference light, wherein the object light and the interference fringe are recorded simultaneously.

Digital holography, Michelson interferometer, Mach-Zehnder interferometer, interference fringe, object light, reference light

Description

System and method for recording of objective wave, reference wave and interference pattern in digital holography system}

Figure 1 shows one preferred embodiment of a holographic system according to the present invention.

Figure 2 shows another preferred embodiment of the holographic system according to the present invention.

Figure 3 shows another preferred embodiment of the holographic system according to the present invention.

4 is a flowchart for explaining a preferred embodiment of the holographic recording method according to the present invention.

FIG. 5 is a flowchart for explaining an example of step S106 of FIG. 4.

<Explanation of symbols for the main parts of the drawings>

Reference Signs List 101: laser, 102: light diffuser, 103: 45 ° polarizer, 104: first light splitter, 105: first horizontal polarizer, 106: reflector, 107: object, 108: second light splitter, 109: second horizontal Polarizer 110: second CCD 111; Second vertical polarizer, 112: first CCD

201: laser, 202: light diffuser, 203: 45 ° polarizer, 204: first light splitter, 206: first reflector, 205: first horizontal polarizer, 206: reflector, 207: object, 208: second light splitter 209: second horizontal polarizer, 210: second CCD, 211: vertical polarizer, 212: first CCD, 213: second reflector, 214: third light splitter

301: laser, 302: light diffuser, 303: 45 ° polarizer, 304: first light splitter, 305: first horizontal polarizer, 306: first reflector, 307: object, 308: second light splitter, 309: first 2 horizontal polarizer, 310: second CCD, 311: vertical polarizer, 312: first CCD, 313: second reflector

The present invention relates to the measurement of reference light, object light, and interference fringes for various applications of digital holograms, and more particularly to the structure of a reflective Michelson interferometer using polarized light and an object light in a transmissive and reflective Mach-Zehnder interferometer structure. And a recording system and method capable of simultaneously measuring interference fringes.

In the case of a charge-coupled device (CCD) camera, a recording medium used for digital holography, the recordable spatial frequency is less than 100 line / mm. Therefore, a 3D image is reproduced by acquiring holographic interference fringes on-axis.

The elimination of zero-order diffraction light is a very important topic in the application of digital holography. In principle, the perfect removal of zero-order diffraction light is possible only with reference light, object light and interference fringe.

One method of zero-order diffraction light removal is to use object and reference light with interference fringes (U. Schnars and W. Jueptner, "Digital Holography", Springer, 3.3.1 Supperssion of the DC term). This can theoretically completely eliminate zero-order diffracted light. However, it is meaningful that the three types of recording light are directly related to each other. Therefore, when the object to be recorded is moved or changed in real time and there is a difference in the recording time between the object light and the interference fringe, there is a problem that the correlation between the two data is reduced and the correct signal processing is not performed.

SUMMARY OF THE INVENTION An object of the present invention for solving the above problems of the prior art is to provide a holographic recording system in which zero-order diffracted light for an object that changes or moves rapidly in time is efficiently removed.

In accordance with another aspect of the present invention, there is provided a digital holography system comprising: a laser for generating light from an incoherent light source; a light diffuser for diffusing light generated by the laser; A light splitter dividing the diffused light into an object light and a reference light; And a holographic recording system using an interferometer structure for effectively removing zero-order diffracted light by having at least one reflector for reflecting the object light and / or reference light, comprising: a first CCD for recording the object light; And a second CCD for recording the interference fringes of the object light and the reference light, wherein the object light and the interference fringe are simultaneously recorded.

The holographic recording system further includes two polarizers polarized in a first direction and one polarizer polarized in a second direction, thereby injecting light polarized in a second direction to the first CCD, and the second CCD. Incident light polarized in the first direction, the reference light is polarized in a first direction in advance and incident only on a second CCD, and the first and second directions are perpendicular or horizontal polarization directions perpendicular to each other. You can do

The interferometer structure may be any one of a reflective Michelson interferometer, a reflective Mach-Zehnder interferometer, and a transmission Mach-Zehnder interferometer structure.

A holographic recording method using an interferometer structure for effectively removing zero-order diffracted light, the method comprising: (a) generating light with a laser using an incoherent light source; (b) diffusing the light with a light diffuser; (c) dividing the light diffused light into an object light and a reference light by a light splitter; And (d) recording the object light into the first CCD and recording the interference fringes of the object light and the reference light into a second CCD, wherein the object light and the interference fringe are simultaneously recorded. .

Step (d) may include: (d1) polarizing the reference light in a first polarization direction;

(d2) said first CCD recording object light incident in a second polarization direction, and said second CCD recording an interference fringe of said object light and said reference light incident in a first polarization direction, The first direction and the second direction may be characterized in that the perpendicular or horizontal polarization direction perpendicular to each other.

The interferometer structure may be any one of a reflective Michelson interferometer, a reflective Mach-Zehnder interferometer, and a transmission Mach-Zehnder interferometer structure.

Hereinafter, with reference to the accompanying drawings, the configuration and operation of the present invention will be described in detail. Like reference numerals in the drawings denote components that perform the same function.

1 is a configuration of a simultaneous recording system of object light and an interference fringe using two light splitters, two CCDs, and four polarizers in a reflective Michelson interferometer according to a preferred embodiment of the present invention.

That is, in the holography system 100 using the reflection type Michelson interferometer structure considering polarization, the laser 101, the light diffuser 102, the first and second light splitters 104 and 108, the reflector 106, and The first and second CCDs 112 and 110 are provided.

The laser 101 generates light using an incoherent light source. The light diffuser 102 diffuses the light, and the first light splitter 104 splits the light polarized by the polarizer 103 into the object light and the reference light after the light is diffused. The reflector 106 reflects the reference light, and the second light splitter 108 divides the object light reflected and reflected by the target object and the reference light reflected by the reflector. The first CCD 112 records the object light split from the second light splitter 108, and the second CCD 110 records the interference fringes by the object light and the reference light split from the second light splitter 108. do.

In this case, in order to record only the object light in the first CCD 112 and to record the interference fringes of the object light and the reference light in the second CCD 110, only the object light is incident on the first CCD 112, and the second CCD It is required at 110 to make both the object light and the reference light enter. Therefore, the holographic system 100 according to the present exemplary embodiment uses two polarizers 105 and 109 polarized in the first direction and one polarizer 111 polarized in the second direction. At this time, the reference light is previously polarized in the first polarization direction, and if only the light in the second polarization direction is incident on the first CCD 112, only the object light will be recorded in the first CCD 112. It is preferable to arrange | position so that a 1st polarization direction and a 2nd polarization direction may mutually perpendicularly cross.

Referring to FIG. 1, the light projected by the laser 101 passes through the light diffuser 102 and then passes through the polarizer 103. In this case, the polarization direction of the light passing through the polarizer 103 is 45 degrees. This light is divided into a reference light and an object light by the first light splitter 104. The reference light is incident through the first horizontal polarizer 105 to be horizontally polarized. The reference light passing through the first horizontal polarizer 105 is reflected by the reflector 106 and passes through the second light splitter 108 and passes through the second horizontal polarizer 109 to the second CCD 110. In this case, since the reference light has already been horizontally polarized by the first horizontal polarizer 105, the reference light cannot pass through the vertical polarizer 111 and thus cannot enter the first CCD 112.

Meanwhile, the object light passing through the first light splitter 104 is irradiated to the object, and the object light reflected by the object passes through the second light splitter 108 and the vertical polarizer 111 by the first CCD 112. Is recorded. In this case, since the vertical polarizer 111 passes, only the object light is recorded while the horizontally polarized reference light is blocked. In addition, the object light passes through the second light splitter 108, passes through the second horizontal polarizer 109, and interferes with the reference light in the second CCD 110 to be recorded with no interference. The polarizers in the horizontal direction and the vertical direction used may be reversed in direction. That is, since the object light is not polarized in the vertical or horizontal direction until it passes the second light splitter 108, both the first and second CCDs 112 and 110 are recorded. On the other hand, since the reference light is horizontally polarized by the first horizontal polarizer 105 and does not pass through the vertical polarizer 111, the reference light is not recorded in the first CCD 112 but only in the second CCD 110.

The system illustrated in FIG. 1 enables the measurement of interference fringes at the same time. Since the reference light hardly changes with time, the reference light is measured separately in a state in which the object light is blocked by a CCD measuring an interference fringe. As described above, according to the present invention, image data in which the light intensity distributions of the object light and the interference fringe are formed can be obtained at the same time.

2 is a block diagram of a simultaneous recording system of object light and interference fringe using three light splitters, two CCDs and four polarizers in a reflective Mach-Zehnder interferometer according to another preferred embodiment of the present invention.

That is, in the holography system 200 using the reflective Mach-Zehnder interferometer structure considering polarization, the laser 201, the light diffuser 202, the first, second, and third light splitters 204, 208, and 214 and the first , The second reflectors 206 and 213 and the first and second CCDs 212 and 210 are provided.

The laser 201 generates light using an incoherent light source, and the light diffuser 202 diffuses the light. The first light splitter 204 splits the light polarized by the polarizer 203 into the object light and the reference light after the light is diffused, and the first and second reflectors 206 and 213 reflect the reference light to the object light, respectively.

The second light splitter 208 splits the object light reflected by the second reflector 213 and then irradiated onto the object and the reference light reflected by the first reflector 206, and the third light splitter 214 The object light and the reference light split from the second light splitter 208 are split.

The first CCD 212 records the object light split from the third light splitter 214, and the second CCD 210 records the interference fringes by the object light and the reference light split from the third light splitter 214. do.

In this case, the horizontal light polarizer is provided between the first reflector, the second light splitter, the third light splitter, and the second CCD, respectively, and the vertical polarizer is provided between the third light splitter and the first CCD, so that the object light is the third light source. After passing through the light splitter, the first and second CCDs are incident, and the reference light is preferably configured to enter the second CCD only after passing through the third splitter.

2, the light projected by the laser 201 passes through the light diffuser 202 and then passes through the polarizer 203 having a polarization direction of 45 degrees. This light is divided into object light and reference light by the first light splitter 204. The reference light passes through the first horizontal polarizer 205 after being reflected by the first reflector 206. The reference light passing through the first horizontal polarizer 205 enters the second CCD 210 via the second light splitter 208 and the third light splitter 214, through the second horizontal polarizer 209. In this case, since the reference light is polarized in the horizontal direction by the first horizontal polarizer 205, the reference light does not pass through the vertical polarizer 211 and is not recorded in the first CCD 212.

The object light passing through the first light splitter 204 is incident through the second reflector 213. The light reflected by the second reflector 213 is irradiated to the object via the second light splitter 208. The object light reflected by the object is recorded in the first CCD 212 after passing through the second light splitter 208 and the third light splitter 214 and the vertical polarizer 211. In this case, the first CCD 212 records only the object light in a state where the horizontally polarized reference light is blocked. In addition, the object light passing through the third light splitter 214 and the second horizontal polarizer 209 is recorded as an interference fringe by interfering with the reference light in the second CCD 210. The polarizers in the horizontal and vertical directions used in the same manner as described in FIG. 1 may be interchanged with each other. That is, since the object light is not polarized in the vertical or horizontal direction until passing through the third light splitter 214, it is recorded in both the first and second CCDs 212 and 210. On the other hand, since the reference light is horizontally polarized by the first horizontal polarizer 205 and does not pass through the vertical polarizer 211, the reference light is not recorded in the first CCD 212, but only in the second CCD 210.

The measurement of interference fringes is possible at the same time by the system illustrated in FIG. Since the reference light hardly changes with time, the reference light is measured separately in a state in which the object light is blocked by a CCD measuring an interference fringe. With this structure as in Fig. 1, the image data in which the light intensity distributions of the object light and the interference fringe are formed by the present invention can be obtained at the same time.

3 is a block diagram of a simultaneous recording system of object light and interference fringe using two light splitters, two CCDs, and four polarizers in a transmission type Mach-Zehnder interferometer according to another preferred embodiment of the present invention.

That is, in the holography system 300 using a transmission type Mach-Zehnder interferometer structure considering polarization, the laser 301, the first and second light splitters 304 and 308, the first and second reflectors 313 and 306, and the first 2 CCDs 312 and 310 are provided.

The laser 301 generates coherent light, the light diffuser 302 diffuses the light, and the first light splitter 304 diffuses the light and then polarizes the light polarized by the polarizer 303 into the object light and the reference light. Divide.

The first and second reflectors 313 and 306 reflect the object light and the reference light, respectively, and the second light splitter 306 is reflected by the first reflector 313 and then passes through the object and the second reflector ( The reference light reflected by 306 is split.

The first CCD 312 records the object light split from the second light splitter 308, and the second CCD 310 records the interference fringes by the object light and the reference light split from the second light splitter 308. do.

In this case, horizontal polarizers 305 and 309 are provided between the first light splitter 304 and the second reflector 306 and the second light splitter 308 and the second CCD 310, respectively, and the vertical light splitter ( By installing 311 between the second light splitter 308 and the first CCD 312, the object light is incident on the first and second CCDs 312 and 310 after passing through the second light splitter 308, and the reference light is After passing through the second light splitter 308, it is preferable to configure the incident to only the second CCD 310.

Referring to FIG. 3, light passing through the light diffuser 302 passes through the polarizer 303. In this case, the polarization direction of the light passing through the polarizer 303 is 45 degrees. This light is divided into a reference light and an object light by the first light splitter 304. The reference light is incident through the first horizontal polarizer 305.

The reference light passing through the first horizontal polarizer 305 is reflected by the second reflector and passes through the second light splitter 308 to the second CCD 310 through the second horizontal polarizer 309. In this case, since the reference light is polarized in the horizontal direction by the first horizontal polarizer 305, the reference light does not enter the first CCD 312.

The object light passing through the first light splitter 304 is irradiated onto the object after being reflected by the first reflector, and the object light passing through the object passes through the second light splitter 308 and the vertical polarizer 311 to be first. It is recorded on the CCD 312. In this case, the first CCD 312 records only the object light while the horizontally polarized reference light is blocked. In addition, the object light passes through the second light splitter 308 and the second horizontal polarizer 309 and interferes with the reference light to be recorded as an interference fringe in the second CCD 310. The polarizers in the horizontal direction and the vertical direction used as described with reference to FIGS. 1 and 2 may be interchanged with each other. That is, since the object light is not polarized in the vertical or horizontal direction until passing through the second light splitter 308, both the first and second CCDs 312 and 310 are recorded. On the other hand, since the reference light is horizontally polarized by the first horizontal polarizer 305 and does not pass through the vertical polarizer 311, the reference light is not recorded in the first CCD 312, but only in the second CCD 310.

It is possible to measure the interference fringe at the same time by the system illustrated in FIG. Since the reference light hardly changes with time, the reference light is measured separately in a state in which the object light is blocked by a CCD measuring an interference fringe. 1 and 2, the image data in which the light intensity distributions of the object light and the interference fringe are formed according to the present invention can be obtained at the same time with this structure.

4 is a flowchart for explaining a preferred embodiment of the holographic recording system according to the present invention.

First, light is generated using a coherent light source (S100).

Next, the light generated by the laser is diffused by the light diffuser (S102).

Next, the light diffused light is divided into object light and reference light by a light splitter (S104).

Next, the object light is recorded in the first CCD and the object light is recorded in the second CDD with the interference fringe of the reference light (S106). In this case, the object light and the interference fringe are recorded at the same time.

 5 is a flowchart illustrating an example of step S104 of FIG. 4.

That is, in step S106, the object light and the reference light are divided in the step S104 of FIG. 4, and the reference light is polarized in the first polarization direction (S200) and the first CCD records the object light incident in the second polarization direction. The second CCD may be performed by recording interference fringes of the object light and the reference light incident in the first polarization direction.

The method according to FIGS. 4 and 5 may be described in the same way by the respective embodiments illustrated by FIGS. 1 to 3 described above.

In the above, the optimal embodiments have been disclosed in the drawings and specification. Although specific terms have been used herein, they are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

   In the application of digital holography, the removal of zero-order diffracted light is a very important topic. In principle, perfect zero-order diffraction light removal is possible only with reference light, object light, and interference fringe. In such an application, when the object to be recorded moves or changes over time, if the object light and the interference fringe are measured at different times, the correlation between the two data disappears and the zero-order diffraction light removal becomes impossible.

According to the present invention, there is an effect of providing a holographic system and method which is easy to remove zero-order diffracted light by simultaneously measuring the object light and the interference fringe using the polarization characteristic of the light.

In addition, the proposed digital hologram recording system and method may be applied regardless of the classification of the living object, the living object in the fluid moving in real time, etc. There is an effect that can be applied to.

Claims (6)

delete A laser for generating light using an incoherent light source; a light diffuser for diffusing the light generated by the laser; A light splitter dividing the diffused light into an object light and a reference light; A holographic recording system using an interferometer structure for removing zero-order diffracted light by having at least one reflector for reflecting the object light or reference light or object light and reference light, A first CCD for recording the object light; And A second CCD for recording an interference fringe of the object light and the reference light, The object light and the interference fringe are simultaneously recorded, The holographic recording system further comprises two polarizers polarized in the first direction and one polarizer polarized in the second direction, The light polarized in the second direction is incident to the first CCD, and the light polarized in the first direction is incident to the second CCD, but the reference light is polarized in the first direction in advance to enter only the second CCD. And the first and second directions are perpendicular or horizontal polarization directions orthogonal to each other. A laser for generating light using an incoherent light source; a light diffuser for diffusing the light generated by the laser; A light splitter dividing the diffused light into an object light and a reference light; A holographic recording system using an interferometer structure for removing zero-order diffracted light by having at least one reflector for reflecting the object light or reference light or object light and reference light, A first CCD for recording the object light; And A second CCD for recording an interference fringe of the object light and the reference light, The object light and the interference fringe are simultaneously recorded, And the interferometer structure is any one of a reflective Michelson interferometer, a reflective Mach-Zehnder interferometer, and a transmissive Mach-Zehnder interferometer structure. delete A holographic recording method using an interferometer structure for removing zero-order diffracted light, (a) generating light with a laser using an incoherent light source; (b) diffusing the light with a light diffuser; (c) dividing the light diffused light into object light and reference light by a light splitter; And (d) recording the object light into a first CCD, and recording an interference fringe of the object light and the reference light into a second CCD, The object light and the interference fringe are simultaneously recorded, In step (d), (d1) polarizing the reference light in a first polarization direction; (d2) said first CCD recording object light incident in a second polarization direction, and said second CCD recording an interference fringe of said object light and said reference light incident in a first polarization direction, And the first polarization direction and the second polarization direction are perpendicular or horizontal polarization directions perpendicular to each other. The method according to claim 5, And the interferometer structure is any one of a reflective Michelson interferometer, a reflective Mach-Zehnder interferometer, and a transmissive Mach-Zehnder interferometer structure.

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