WO2020162458A1 - Polarization state control device and computer-readable recording medium - Google Patents

Polarization state control device and computer-readable recording medium Download PDF

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Publication number
WO2020162458A1
WO2020162458A1 PCT/JP2020/004144 JP2020004144W WO2020162458A1 WO 2020162458 A1 WO2020162458 A1 WO 2020162458A1 JP 2020004144 W JP2020004144 W JP 2020004144W WO 2020162458 A1 WO2020162458 A1 WO 2020162458A1
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WO
WIPO (PCT)
Prior art keywords
light
retarder
polarization state
control device
state control
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PCT/JP2020/004144
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French (fr)
Japanese (ja)
Inventor
晴継 福本
安藤　道則
山下　達弥
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株式会社デンソー
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Publication of WO2020162458A1 publication Critical patent/WO2020162458A1/en

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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells

Definitions

  • the present disclosure relates to a recording medium that records a program for executing a polarization state control device and a polarization state control method, and more particularly to a technique for controlling a phase delay amount of a retarder.
  • the multilayer polarization grating is offset with respect to the periodic molecular structure of the first polarization grating layer along the interface between the first polarization grating layer and the second polarization grating layer. It has a periodic molecular structure.
  • the third polarization grating layer also has a periodic molecular structure of the second polarization grating layer along the interface between the second polarization grating layer and the third polarization grating layer. It has a periodic molecular structure that is offset.
  • This multilayer polarization diffraction grating reduces the wavelength dependence of diffraction efficiency due to the above configuration.
  • a beam deflecting device configured by arranging a polarization diffraction element having a first birefringence distribution period and a second polarization diffraction element having a second birefringence distribution period in line (in line).
  • a polarization diffraction element having a first birefringence distribution period and a second polarization diffraction element having a second birefringence distribution period in line (in line).
  • the phase delay amount may not be set to the desired value due to the phase delay amount changing in each retarder due to the individual difference of the retarder, deterioration over time, temperature change during use, etc. In this case, there is a problem in that the light of the desired polarization state cannot be emitted from the retarder.
  • the present disclosure aims to provide a polarization state control technique capable of accurately controlling the phase delay amount of a retarder.
  • the polarization state control device is configured to include a linear polarizer, a retarder, a reflection plate, a light receiving unit, and a control unit.
  • the linear polarizer polarizes the source light into linearly polarized light.
  • the light source light that has passed through the linear polarizer is incident on the retarder, and the retarder changes the polarization state of the incident light according to the applied voltage and emits the light.
  • the reflection plate reflects a part of the light source light that has passed through the linear polarizer toward the incident surface side on the exit surface side of the retarder.
  • the light receiving unit receives the light reflected by the reflecting plate and passing through the linear polarizer.
  • the control unit controls the retarder so that light obtained by polarizing the incident light with a phase delay of ⁇ /2 or 0 is emitted from the retarder based on the amount of light received by the light receiving unit. Control the applied voltage.
  • the light source light that has passed through the linear polarizer that polarizes the light source light into linearly polarized light is incident on the retarder.
  • the retarder changes the polarization state of the incident light according to the applied voltage and emits the light.
  • the reflection plate reflects a part of the light source light that has passed through the linear polarizer toward the incident surface side on the exit surface side of the retarder. The light reflected by the reflecting plate and passing through the linear polarizer is received by the light receiving section.
  • the control unit polarizes the incident light with a phase delay of ⁇ /2 or 0 based on the light amount of the light received by the light receiving unit.
  • the voltage applied to the retarder is controlled so that the light is emitted from the retarder. Accordingly, the polarization state control device of the present disclosure can accurately control the phase delay amount of the retarder.
  • the polarization state control device that is the second aspect of the technology of the present disclosure is a quarter that is arranged on the optical path where light is not reflected by the reflection plate and between the linear polarizer and the retarder.
  • a wave plate may be further included.
  • the polarization state control device of the present disclosure circularly polarized light is incident on the retarder, by accurately controlling the phase delay amount of the retarder, from the retarder of the circularly polarized light controlled in the desired rotation direction. Light can be emitted.
  • the polarization state control device is arranged on the optical path where light is reflected by the reflection plate, and is disposed between the linear polarizer and the retarder. It can be configured to further include a four-wave plate.
  • the polarization state control device can be configured to further include a polarization grating on which the light emitted from the retarder is incident.
  • the reflection plate can reflect light that has not been incident on the polarization grating.
  • the polarization state control device of the present disclosure can accurately control the phase delay amount of the light incident from the retarder to the polarization grating, and thus maximize the diffraction efficiency of the light emitted from the polarization grating. it can.
  • the polarization state control device can stack a plurality of combinations of the retarder and the polarization grating.
  • the reflection plate and the light receiving unit are provided corresponding to each of the combinations.
  • the control unit may control the voltage applied to the retarders that form the combination corresponding to the light receiving units, based on the amount of light received by each of the light receiving units.
  • the control unit controls the voltage applied to the retarder so that the amount of light received by the light receiving unit is maximized. be able to. Accordingly, the polarization state control device of the present disclosure uses the luminous intensity of the light reflected by the reflection plate and passed through the retarder and the linear polarizer again, so that the voltage value that maximizes the light amount is ⁇ /2 or 0. Can be used as a voltage value for setting the amount of phase delay.
  • the linear polarizer emits P-polarized light in an incident direction and emits S-polarized light in a direction orthogonal to the incident direction. It is a polarization beam splitter.
  • the light receiving unit receives the S-polarized light emitted from the polarization beam splitter, and the control unit applies the light to the retarder so that the amount of the S-polarized light received by the light receiving unit is minimized.
  • the voltage applied can be controlled.
  • the polarization state control device of the present disclosure uses the luminous intensity of the S-polarized light that has been reflected by the reflection plate and passed through the retarder and the polarization beam splitter again, so that the voltage value that minimizes the light amount is ⁇ / It may be a voltage value for setting the phase delay amount of 2 or 0.
  • the control unit has a preset characteristic of the amount of phase delay with respect to the voltage applied to the retarder, which is lower than a predetermined voltage value. In the first numerical range of values, a voltage value with a phase delay amount of ⁇ /2 is searched for, and in a second numerical value range of voltage values higher than the predetermined voltage value, a voltage value with a phase delay amount of 0 is searched for. can do. Further, in the polarization state control device which is the ninth aspect of the technology of the present disclosure, the control unit has a phase characteristic of ⁇ /2 or 0 in a preset characteristic of a phase delay amount with respect to a voltage applied to the retarder.
  • the voltage value applied to the retarder may be searched in the vicinity of the voltage value corresponding to the delay amount. Accordingly, the polarization state control device of the present disclosure can accurately search for a voltage value corresponding to the phase delay amount ⁇ /2 and a voltage value corresponding to the phase delay amount 0.
  • a polarization state control method that is another aspect of the technology of the present disclosure is a method for realizing the function provided by the polarization state control device.
  • a polarization state control program that is another aspect of the technology of the present disclosure is a program for executing the polarization state control method, and is a program for causing a computer to function as a control unit of the polarization state control device. is there.
  • a recording medium that is another aspect of the technique of the present disclosure is a recording medium that records the above-mentioned polarization state control program.
  • the retarder and the linear polarizer are applied to the retarder so that the phase delay amount becomes ⁇ /2 or 0 based on the light amount of the light that has passed through the retarder and the linear polarizer again. Control the voltage. Accordingly, the technique of the present disclosure can accurately control the phase delay amount of the retarder.
  • FIG. 1 It is a schematic diagram showing the composition of the polarization control device concerning a 1st embodiment. It is a functional block diagram of a control part. It is a figure which shows an example of the relationship between a voltage and a light quantity. It is a figure for demonstrating the relationship between the amount of light and the amount of phase delays. It is a figure which shows an example of a voltage-phase delay amount characteristic. It is a flow chart which shows an example of polarization state control processing. It is a schematic diagram showing composition of a polarization control device concerning a 2nd embodiment.
  • FIG. 6 is a diagram for explaining a temperature change of a voltage-phase delay amount characteristic.
  • the polarization state control device 10 includes a linear polarizer 12, a retarder 14, a mirror 16, a light receiving unit 18, a control unit 20, a control power supply 22, and The first and second electrodes 24L and 24R are included.
  • the linear polarizer 12 polarizes the light (L1) emitted from the laser light source 26 into linearly polarized light (L2) and emits it.
  • the retarder 14 is a ⁇ /2 plate, and is provided with first and second electrodes 24L and 24R partially connected to the control power supply 22.
  • the ⁇ /2 plate is a 1 ⁇ 2 wavelength plate that rotates the polarization direction of linearly polarized light.
  • the retarder 14 receives the light (L2) emitted from the linear polarizer 12 and also emits the light (L3) in which the polarization state of the incident light is changed according to the applied voltage.
  • Mirror 16 is an example of a reflector in the technique of the present disclosure.
  • the mirror 16 is provided on the emission surface So side of the retarder 14, and reflects a part (L4) of the light emitted from the linear polarizer 12 to the incidence surface Si side on the emission surface So side of the retarder 14.
  • Part of the light emitted from the linear polarizer 12 enters from the incident surface Si of the retarder 14 and reaches the reflecting surface of the mirror 16 provided on the exit surface So side.
  • the light (reflected light) reflected by the mirror 16 travels from the exit surface So side of the retarder 14 to the entrance surface Si side.
  • the light receiving unit 18 receives the light (L5) reflected by the mirror 16 and passing through the linear polarizer 12, and outputs the light amount data indicating the light amount of the received light.
  • the light receiving unit 18 is, for example, a light amount monitor.
  • the control unit 20 can be realized by a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory).
  • the computer functions as the control unit 20 of the polarization state control device 10 by the CPU executing the polarization state control program.
  • the ROM stores a polarization state control program for executing a polarization state control process described later.
  • the ROM is an example of a recording medium that records the program.
  • control unit 20 includes a light amount acquisition unit 42, a voltage value determination unit 44, a voltage control unit 46, and a DB (database) 48.
  • the light amount acquisition unit 42 acquires the light amount data output from the light receiving unit 18, and transfers it to the voltage value determination unit 44.
  • the voltage value determination unit 44 causes the light incident on the retarder 14 to be polarized with a phase delay of ⁇ /2 or 0 and to be emitted from the retarder 14 based on the light amount data passed from the light amount acquisition unit 42. , The voltage value applied to the retarder 14 is determined.
  • FIG. 3 schematically shows an example of the relationship between the voltage applied to the retarder 14 and the light amount obtained from the light receiving unit 18.
  • the voltage value determination unit 44 sets the voltage value at which the light amount indicated by the light amount data passed from the light amount acquisition unit 42 becomes the maximum voltage value as the voltage value at which the phase delay amount becomes ⁇ /2 or 0. decide.
  • the principle that the amount of light emitted from the linear polarizer 12 is maximized when the phase delay amount of the retarder 14 is ⁇ /2 or 0 will be described.
  • the retarder 14 when the phase delay amount of the retarder 14 is ⁇ /2 (1/2 wavelength), the retarder 14 operates as a ⁇ /2 plate as shown in FIG. Therefore, when the angle between the plane of polarization of linearly polarized light and the fast axis of the retarder 14 is ⁇ , the angle between the plane of polarization and the fast axis becomes 2 ⁇ after passing through the retarder 14 once.
  • the retarder 14 rotates the polarization direction of the incident light by 2 ⁇ and emits it. That is, the plane of polarization of the incident light changes to a position folded back with respect to the fast axis.
  • the polarization plane of the light emitted from the retarder 14 changes to a position folded back with respect to the fast axis by the same principle. That is, the polarization plane of the emitted light returns to the original position. Therefore, in the configuration of the first embodiment, the plane of polarization of the emitted light and the pass axis of the linear polarizer 12 match. Therefore, the amount of light emitted from the linear polarizer 12 is maximized.
  • the phase delay amount of the retarder 14 is 0, the polarization plane of the linearly polarized light does not change even after passing through the retarder 14. Further, the polarization plane of the emitted light does not change even after the emitted light from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again. Therefore, in the configuration of the first embodiment, the plane of polarization of the emitted light and the pass axis of the linear polarizer 12 match. Therefore, the amount of light emitted from the linear polarizer 12 is maximized.
  • the voltage value determination unit 44 determines the voltage value applied to the retarder 14. Specifically, the voltage value determination unit 44 searches the predetermined search range (within the numerical range) while changing the voltage applied to the retarder 14, and the voltage value that maximizes the light amount based on the search result. To decide. The voltage value determination unit 44 determines a predetermined search range with reference to the DB 48.
  • the DB 48 is a database in which the characteristics of the phase delay amount with respect to the voltage applied to the retarder 14 (hereinafter referred to as “voltage-phase delay amount characteristics”) are stored. For example, when the retarder 14 starts to be used, the phase delay amount is measured while changing the applied voltage, and the data indicating the voltage-phase delay amount characteristic can be stored based on the voltage value and the measured value. .. FIG. 5 shows an example of the voltage-phase delay amount characteristic stored in the DB 48.
  • the voltage-phase delay amount characteristic shows a monotonically decreasing curve. Therefore, in the voltage-phase delay amount characteristic stored in the DB 48, the voltage value determination unit 44 sets an arbitrary voltage value between the voltage value at which the phase delay amount becomes ⁇ /2 and the voltage value at which the phase delay amount becomes 0 as a threshold value. Set. Then, the voltage value determination unit 44 searches for a voltage value at which the phase delay amount is ⁇ /2, with the numerical value range (first numerical value range) of the voltage value lower than the set threshold value as the search range (first search range). ..
  • the voltage value determination unit 44 searches for a voltage value at which the phase delay amount is 0, with the numerical range (second numerical range) of the voltage value higher than the set threshold value as the search range (second search range). In this case, instead of the voltage-phase delay amount characteristic as shown in FIG. 5, only the voltage value serving as the predetermined threshold value may be stored.
  • the voltage value determination unit 44 sets the vicinity of the voltage value corresponding to the phase delay amount of ⁇ /2 or 0, for example, the numerical value range of a predetermined voltage value before and after including the voltage value.
  • the search range a voltage value at which the phase delay amount becomes ⁇ /2 or 0 may be searched.
  • the voltage-phase delay amount characteristic shown in FIG. 5 instead of the voltage-phase delay amount characteristic shown in FIG. 5, only the voltage values corresponding to the phase delay amounts of ⁇ /2 and 0 may be stored.
  • the voltage value determination unit 44 sets the voltage value search range as described above, and in the relationship between the voltage and the light amount as shown in FIG. It is possible to accurately search for
  • the voltage value determination unit 44 transfers the determined voltage value to the voltage control unit 46.
  • the voltage control unit 46 sets the voltage value transferred from the voltage value determination unit 44 in the control power supply 22.
  • the control power supply 22 applies the voltage of the set voltage value to the retarder 14 via the first and second electrodes 24L and 24R.
  • the control power supply 22 applies a voltage so that the phase delay amount of the retarder 14 is set to ⁇ /2 or 0, and the polarization plane of the linearly polarized light (L3) emitted from the retarder 14 Can be switched to the desired direction.
  • the voltage controller 46 controls the voltage applied to the retarder 14 so that the light polarized with the phase delay of ⁇ /2 or 0 is emitted from the retarder 14.
  • a part (L1) of the laser light emitted from the laser light source 26 enters the linear polarizer 12 and is linearly polarized by the linear polarizer 12.
  • the linearly polarized light (L2) is emitted from the linear polarizer 12 and is incident on the retarder 14. Then, the retarder 14 changes the polarization state of the incident light according to the phase delay amount set in the retarder 14 and emits the polarized light (L3).
  • a part (L20) of the laser light emitted from the laser light source 26 enters the linear polarizer 12 and is linearly polarized by the linear polarizer 12.
  • the linearly polarized light (L4) is emitted from the linear polarizer 12 and is incident on the retarder 14.
  • the light reaching the emission surface So of the retarder 14 is reflected by the reflection surface of the mirror 16.
  • the reflected light passes through the retarder 14 and the linear polarizer 12 again (L5), and is received by the light receiving unit 18.
  • the light receiving unit 18 outputs light amount data indicating the light amount of the received light. Then, the control unit 20 executes the polarization state control process shown in FIG. As a result, the phase delay amount of the retarder 14 is set to ⁇ /2 or 0.
  • the voltage value determination unit 44 refers to the data regarding the voltage-phase delay amount characteristic stored in the DB 48, and determines that the predetermined threshold value is exceeded.
  • the numerical value range of the low voltage value is set as the search range for searching the voltage value where the phase delay amount is ⁇ /2.
  • the voltage value determination unit 44 sets a numerical value range of voltage values higher than a predetermined threshold value as a search range for searching for a voltage value with a phase delay amount of 0.
  • the voltage value determining unit 44 sets the vicinity of the voltage value corresponding to the phase delay amount of ⁇ /2 or 0, for example, the numerical value range of a predetermined voltage value before and after including the voltage value. You may set as a search range.
  • step S14 the voltage value determination unit 44 causes the voltage value corresponding to the initial value (first search value) within the search range set by the process of step S12 (for example, the minimum voltage value within the numerical range). Is output to the voltage control unit 46.
  • the voltage control unit 46 sets the voltage value input from the voltage value determination unit 44 in the control power supply 22.
  • step S16 the control power supply 22 applies the voltage having the set voltage value to the retarder 14 via the first and second electrodes 24L and 24R.
  • the light amount acquisition unit 42 acquires the light amount data output from the light receiving unit 18 when the control power supply 22 applies a voltage.
  • step S18 the voltage value determination unit 44 stores the voltage value set by the process of step S14 and the light amount acquired by the process of step S16 as a set of data.
  • step S20 the voltage value determination unit 44 determines whether or not the processes of steps S16 and S18 have been completed for the voltage values within the search range set by the process of step S12 (end of search). Is determined).
  • step S22 the voltage value determination unit 44 changes and sets the voltage value to a value shifted by a predetermined value (a value obtained by increasing or decreasing the voltage value by a predetermined value), and then returns to step S16.
  • step S24 the voltage value determination unit 44 determines whether or not the processes of steps S16 and S18 have been completed for the voltage values within the search range set by the process of step S12 (end of search). Is determined).
  • step S22 the voltage value determination unit 44 changes and sets the voltage value to a value shifted by a predetermined value (a value obtained by increasing or decreasing the voltage value by a predetermined value), and then returns to step S16.
  • step S24 the voltage value determination unit 44 determines whether or not the processes of steps S16 and S18 have been completed for the voltage values within the search range set by the process
  • step S24 the voltage value determination unit 44 sets the voltage value of the group data having the maximum light amount, out of the group data of the voltage value and the light amount stored by the process of step S18, to the phase delay of ⁇ /2 or 0. It is determined as the voltage value corresponding to the quantity.
  • the voltage value determination unit 44 outputs the determined voltage value to the voltage control unit 46.
  • the voltage control unit 46 sets the voltage value input from the voltage value determination unit 44 in the control power supply 22, and the polarization state control process ends.
  • the polarization state control device 10 As described above, according to the polarization state control device 10 according to the first embodiment, the amount of light that is reflected by the exit surface So side of the retarder 14 and passes through the linear polarizer 12 again to be output is monitored. ing. Then, the polarization state control device 10 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light becomes maximum. Thereby, the polarization state control device 10 can set the phase delay amount of the retarder 14 to ⁇ /2 or 0. As a result, as shown in FIG.
  • the polarization state control device 10 sets the polarization plane of the linearly polarized light of the light emitted from the retarder 14 to a desired state ( Switch to (polarization state).
  • the polarization state control device 10 can emit the light (L3) whose polarization state has been changed by the retarder 14.
  • the polarization state control device 10 according to the first embodiment can accurately control the phase delay amount of the retarder 14.
  • the angle ⁇ formed by the polarization plane of the linearly polarized light incident on the retarder 14 and the fast axis of the retarder 14 is set to 45 degrees so that 2 ⁇ becomes 90 degrees. Set. In this case, the plane of polarization of the incident light is rotated by 90 degrees. Therefore, in the configuration of the first embodiment, for example, linearly polarized light having a horizontal polarization plane can be switched to linearly polarized light having a vertical polarization plane.
  • the polarization state control device 210 has an optical path on which light from the laser light source 26 is not reflected by the mirror 16.
  • the ⁇ /4 plate 28 is arranged between the linear polarizer 12 and the retarder 14.
  • the ⁇ /4 plate 28 is a quarter wavelength plate that converts linearly polarized light into circularly polarized light.
  • the ⁇ /4 plate 28 receives the linearly polarized light (L2) emitted from the linear polarizer 12 and converts the linearly polarized light into circularly polarized light and emits it (L6).
  • the rotation direction of the circularly polarized light emitted from the ⁇ /4 plate 28 may be clockwise or counterclockwise.
  • the circularly polarized light (L6) When the circularly polarized light (L6) is incident on the retarder 14, the circularly polarized light (L7) is rotated clockwise or counterclockwise according to the set phase delay amount of ⁇ /2 or 0. Is emitted.
  • the polarization state control device 210 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light becomes maximum. Accordingly, the polarization state control device 210 can set the phase delay amount of the retarder 14 to ⁇ /2 or 0. As a result, as shown in FIG. 7, when the circularly polarized light (L6) is incident on the retarder 14, the polarization state control device 210 causes the clockwise or counterclockwise circularly polarized light depending on the phase delay amount. (L7) can be emitted.
  • the polarization state control device 310 in addition to the configuration of the polarization state control device 210 according to the second embodiment, has a polarization grating (on which the light emitted from the retarder 14 enters). A polarization diffraction grating) 30 is further included.
  • the mirror 16 is arranged on the exit surface So side of the retarder 14 and at a position capable of reflecting the light before entering the polarization grating 30.
  • the polarization grating 30 diffracts the incident light according to the set diffraction angle and emits it (L8).
  • the polarization state control device 310 controls the voltage applied to the retarder 14 so that the light amount of the light becomes maximum based on the light amount as the monitoring result. Thereby, the polarization state control device 310 can set the phase delay amount of the retarder 14 to ⁇ /2 or 0. As a result, as shown in FIG. 8, when the circularly polarized light (L6) enters the retarder 14, the polarization state control device 310 emits the light (L8) diffracted according to the diffraction angle from the retarder 14. can do.
  • the rotation direction of the circularly polarized light incident on the polarization grating 30 is exactly left-handed or right-handed circularly polarized light, the diffraction efficiency by the polarization grating 30 is maximized.
  • the light incident on the polarization grating 30 becomes elliptically polarized light instead of circularly polarized light, the diffraction efficiency decreases. Therefore, in order to maximize the diffraction efficiency, the light emitted from the retarder 14 needs to be accurately circularly polarized.
  • the polarization state control device 410 includes the light from the laser light source 26 reflected by the mirror 16.
  • a ⁇ /4 plate 428 is arranged on the road between the linear polarizer 12 and the retarder 14.
  • the ⁇ /4 plate 428 is located on the optical path where the light from the laser light source 26 is not reflected by the mirror 16 and between the linear polarizer 12 and the retarder 14 ( An example integrated with the ⁇ /4 plate 28) in the second and third embodiments is shown.
  • the ⁇ /4 plate 428 reflects the circularly polarized light (L9) that has passed through the retarder 14 again after being reflected by the mirror 16, and converts the circularly polarized light into linearly polarized light and emits the linearly polarized light (L10).
  • the principle that the amount of light emitted from the linear polarizer 12 is maximized when the phase delay amount of the retarder 14 is ⁇ /2 or 0 will be described.
  • the retarder 14 operates as a ⁇ /2 plate. Therefore, the light emitted from the retarder 14 becomes circularly polarized light in the rotation direction opposite to the rotation direction of the circularly polarized light of the incident light to the retarder 14.
  • the light emitted from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again, it becomes circularly polarized light in the opposite rotation direction by the same principle. That is, the rotation direction of the circularly polarized light of the light (L9) reflected by the mirror 16 and emitted from the retarder 14 returns to the circularly polarized state of the light incident on the retarder 14.
  • the polarization plane of the light (L10) emitted from the ⁇ /4 plate 428 and the linear polarizer 12 Coincides with the passing axis of. Therefore, the amount of light emitted from the linear polarizer 12 (L5) is maximized.
  • the rotation direction of circularly polarized light does not change even after passing through the retarder 14. Even after the light emitted from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again, the rotation direction of circularly polarized light does not change. Further, when the circularly polarized light is incident on the ⁇ /4 plate 428, the plane of polarization of the emitted light (L10) from the ⁇ /4 plate 428 and the pass axis of the linear polarizer 12 coincide with each other. Therefore, the amount of light emitted from the linear polarizer 12 (L5) is maximized.
  • the polarization state control device 410 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light becomes maximum. Accordingly, the polarization state control device 410 can set the phase delay amount of the retarder 14 to ⁇ /2 or 0. As a result, the polarization state control device 410 can cause circularly polarized light (L6) whose rotation direction is exactly left-handed or right-handed to enter the polarization grating 30, as shown in FIG. The polarization state control device 410 can maximize the diffraction efficiency of the light (L8) emitted from the polarization grating 30.
  • the polarization state control device 510 includes a polarization beam splitter 512 and a control unit instead of the linear polarizer 12 and the control unit 20 of the polarization state control device 310 according to the third exemplary embodiment.
  • the unit 520 is provided.
  • the polarization beam splitter 512 emits P-polarized light (L11, L13) in the incident direction of the light (L1, L20) incident on the polarization beam splitter 512.
  • the polarization beam splitter 512 emits S-polarized light (L12, L14) in a direction orthogonal to the incident direction of the light incident on the polarization beam splitter 512.
  • the light receiving unit 18 receives the light (L17), which is the reflected light (L15) reflected by the mirror 16 and is incident on the polarization beam splitter 512 and is emitted as S-polarized light, and outputs light amount data indicating the light amount of the received light. To do.
  • control unit 520 includes a light amount acquisition unit 42, a voltage value determination unit 544, a voltage control unit 46, and a DB 48 that stores a voltage-phase delay amount characteristic. It is configured to include.
  • the voltage value determination unit 544 sets the voltage value at which the amount of light indicated by the light amount data passed from the light amount acquisition unit 42 becomes the minimum voltage value as the voltage value at which the phase delay amount becomes ⁇ /2 or 0. decide.
  • the principle that the amount of light emitted from the polarization beam splitter 512 (S-polarized light) is minimized when the phase delay amount of the retarder 14 is ⁇ /2 or 0 will be described.
  • the retarder 14 operates as a ⁇ /2 plate as shown in FIG. Therefore, when the angle between the plane of polarization of linearly polarized light and the fast axis of the retarder 14 is ⁇ , the angle between the plane of polarization and the fast axis becomes 2 ⁇ after passing through the retarder 14 once. That is, the plane of polarization of the incident light changes to a position folded back with respect to the fast axis.
  • the polarization plane of the light emitted from the retarder 14 changes to a position folded back with respect to the fast axis by the same principle.
  • the polarization plane of the emitted light returns to the original position. Therefore, in the configuration of the fifth embodiment, the light emitted from the retarder 14 becomes P-polarized light. Therefore, when the light is incident on the polarization beam splitter 512, the light amount of the S-polarized component becomes the minimum.
  • the phase delay amount of the retarder 14 is 0, the P-polarized light does not change even after passing through the retarder 14. Furthermore, the P-polarized light of the emitted light does not change even after the emitted light from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again. Therefore, in the configuration of the fifth embodiment, the light emitted from the retarder 14 becomes P-polarized light. Therefore, when the light is incident on the polarization beam splitter 512, the light amount of the S-polarized component becomes the minimum.
  • a part (L1) of the laser light emitted from the laser light source 26 enters the polarization beam splitter 512 and is polarized by the polarization beam splitter 512.
  • the P-polarized emitted light (L11) is emitted in the incident direction
  • the S-polarized emitted light (L12) is emitted in the direction orthogonal to the incident direction.
  • the P-polarized outgoing light (L11) is converted into circularly polarized light via the ⁇ /4 plate 28, and the circularly polarized light (L6) is incident on the retarder 14.
  • the retarder 14 emits polarized light according to the phase delay amount set in the retarder 14.
  • the light emitted from the retarder 14 enters the polarization grating 30.
  • the polarization grating 30 emits light (L8) diffracted at the diffraction angle set for the polarization grating 30.
  • a part (L20) of the laser light emitted from the laser light source 26 enters the polarization beam splitter 512 and is polarized by the polarization beam splitter 512.
  • the P-polarized emitted light (L13) is emitted in the incident direction
  • the S-polarized emitted light (L14) is emitted in the direction orthogonal to the incident direction.
  • the P-polarized outgoing light (L13) enters the retarder 14.
  • the light reaching the emission surface So of the retarder 14 is reflected by the reflection surface of the mirror 16.
  • the reflected light again passes through the retarder 14 and enters the polarization beam splitter 512 (L15).
  • the polarization beam splitter 512 emits P-polarized outgoing light (L16) in the incident direction, and emits S-polarized outgoing light (L17) in the direction orthogonal to the incident direction.
  • the light receiving unit 18 receives the S-polarized outgoing light (L17) from the polarization beam splitter 512, and outputs light amount data indicating the light amount of the received light. Then, the control unit 520 executes the polarization state control process shown in FIG. As a result, the phase delay amount of the retarder 14 is set to ⁇ /2 or 0.
  • the polarization state control process according to the first embodiment performs a process of searching for a voltage value that maximizes the light amount, whereas the polarization state control process according to the fifth embodiment determines a voltage value that minimizes the light amount. Perform the process of searching.
  • the process of the fifth embodiment is different from the process of the first embodiment only in this point, and thus the description thereof is omitted.
  • the light intensity is monitored.
  • the polarization state control device 510 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light is minimized.
  • the polarization state control device 510 can set the phase delay amount of the retarder 14 to ⁇ /2 or 0.
  • the polarization state control device 510 can enter the circularly polarized light (L6) whose rotation direction is exactly left-handed or right-handed into the polarization grating 30, as shown in FIG.
  • the polarization state control device 510 can maximize the diffraction efficiency of the emitted light (L8) from the polarization grating 30.
  • the retarder 14 and the polarization grating 30 of the polarization state control device 310 according to the third embodiment are combined so that the main surfaces thereof face each other. At least two layers are provided (a plurality of layers are stacked). In the example of FIG.
  • the first layer of the combination of the retarder (first retarder) 14A and the polarization grating (first polarization grating) 30A, the retarder (second retarder) 14B and the polarization grating (second polarization grating) 30B The case where it is configured by the second layer of the combination and the third layer of the combination of the retarder (third retarder) 14C and the polarization grating (third polarization grating) 30C is illustrated.
  • the retarders 14 and the polarization gratings 30 in each layer are arranged alternately.
  • the retarder 14A is provided with first and second electrodes 24AL and 24AR
  • the retarder 14B is provided with first and second electrodes 24BL and 24BR
  • the retarder 14C is provided with first and second electrodes 24CL and 24CR.
  • a voltage is applied to each of the retarders 14 at an individually set voltage value.
  • Mirrors 16A, 16B and 16C and light receiving portions 18A, 18B and 18C are provided corresponding to each of the first layer, the second layer and the third layer of the combination.
  • reference numerals A, B, and C are omitted.
  • Each of the mirrors 16 is located on the emission surface So side of the retarder 14 forming the combination of the corresponding layers and at a position that reflects the light before being incident on the polarization grating 30 forming the combination of the corresponding layers. Will be placed.
  • the polarization state control device 610 according to the sixth embodiment includes a control unit 620 instead of the control unit 20 of the polarization state control device 310 according to the third embodiment.
  • control unit 620 includes a light amount acquisition unit 42, a voltage value determination unit 644, a voltage control unit 646, and a DB 48 that stores a voltage-phase delay amount characteristic. It is configured to include.
  • the voltage value determination unit 644 determines the voltage value to be applied to the retarder 14 that constitutes the combination of layers corresponding to each light receiving unit 18, based on the light amount data acquired from each of the light receiving units 18.
  • the method of determining the voltage value is the same as the method shown in the first to fourth embodiments.
  • the voltage control unit 646 applies the voltage value corresponding to each layer determined by the voltage value determination unit 644 to the retarder 14 that forms a combination of corresponding layers via the first and second electrodes 24L and 24R. As described above, the power source for control 22 is set.
  • the polarization state control device 610 As described above, according to the polarization state control device 610 according to the sixth embodiment, two or more layers in which the retarder 14 and the polarization grating 30 are combined are provided.
  • the polarization state control device 610 independently sets the phase delay amount of the retarder 14 of each layer to ⁇ /2 or 0. Thereby, the polarization state control device 610 can diffract the emitted light in a plurality of directions by using the single light source by the plurality of polarization gratings 30.
  • the polarization state control device stores the voltage-phase delay amount characteristic in advance for each of a plurality of different temperatures, monitors the ambient temperature, and measures the voltage-phase delay amount corresponding to the ambient temperature. You may select a characteristic and determine a voltage value like each above-mentioned embodiment.
  • the polarization state control device not only shifts the phase delay amount due to the individual difference of the retarder 14 or deterioration over time, but also shifts the phase delay amount due to the temperature change during use. Therefore, the amount of phase delay can be optimized at all times.
  • the above embodiments can be combined and implemented.
  • the combination of the retarder 14 and the polarization grating 30 may be a multilayer configuration.
  • the polarization state control program for executing the polarization state control processing according to each of the above embodiments may be recorded in a computer-readable recording medium and provided.
  • the configuration capable of obtaining emitted light in a desired polarization state as in each of the above-described embodiments can be used in a light beam scanner such as a laser radar, a laser processing machine, or the like.

Abstract

This polarization state control device is configured to include a linear polarizer 12, a retarder 14, a reflecting plate 16, a light receiving unit 18, and a control unit 20. Source light that has passed through the linear polarizer 12 for polarizing the source light into linearly polarized light is incident on the retarder 14. The retarder 14 emits the incident light after changing the polarization state of the incident light according to applied voltage. The reflecting plate 16 reflects, on the emission surface So side of the retarder 14, part of the source light that has passed through the linear polarizer 12 to the incidence surface Si side. The light receiving unit 18 receives light reflected by the reflecting plate 16 and passing through the linear polarizer 12, and outputs light amount data indicating the light amount of the received light. The control unit 20 controls voltage to be applied to the retarder 14 on the basis of the light amount inputted from the light receiving unit 18 such that light obtained by polarizing the incident light with a phase delay of λ/2 or 0 is emitted from the retarder 14.

Description

偏光状態制御装置及びコンピュータが読取可能な記録媒体Polarization state control device and computer-readable recording medium
　本開示は、偏光状態制御装置及び偏光状態制御方法を実行するためのプログラムを記録した記録媒体に係り、特に、リターダの位相遅れ量を制御する技術に関する。 The present disclosure relates to a recording medium that records a program for executing a polarization state control device and a polarization state control method, and more particularly to a technique for controlling a phase delay amount of a retarder.
　従来、第１層から第３層の偏光回折層から構成される多層偏光回折格子が提案されている（特許文献１参照）。この多層偏光回折格子は、第１の偏光回折格子層と第２の偏光回折格子層との間の界面に沿って、第１の偏光回折格子層の周期的分子構造に対してオフセットされている周期的分子構造を有している。また、第３の偏光回折格子層も、第２の偏光回折格子層と第３の偏光回折格子層との間の界面に沿って、第２の偏光回折格子層の周期的分子構造に対してオフセットされている周期的分子構造を有している。この多層偏光回折格子は、上記の構成により、回折効率の波長依存性を低減している。 Conventionally, a multilayer polarization diffraction grating including first to third polarization diffraction layers has been proposed (see Patent Document 1). The multilayer polarization grating is offset with respect to the periodic molecular structure of the first polarization grating layer along the interface between the first polarization grating layer and the second polarization grating layer. It has a periodic molecular structure. The third polarization grating layer also has a periodic molecular structure of the second polarization grating layer along the interface between the second polarization grating layer and the third polarization grating layer. It has a periodic molecular structure that is offset. This multilayer polarization diffraction grating reduces the wavelength dependence of diffraction efficiency due to the above configuration.
　また、第１の複屈折率分布の周期を有する偏光回折素子と、第２の複屈折率分布の周期を有する偏光回折素子とを、一列に並べて（インラインに）配置して構成したビーム偏向装置が提案されている（特許文献２参照）。 A beam deflecting device configured by arranging a polarization diffraction element having a first birefringence distribution period and a second polarization diffraction element having a second birefringence distribution period in line (in line). Has been proposed (see Patent Document 2).
　また、光学異方性を有する物質の複屈折を利用して、光の偏光状態を電気的に変える液晶リターダの駆動方法が提案されている（特許文献３参照）。この駆動方法は、液晶リターダへの印加電圧Ｖが閾値電圧Ｖｔｈより大きい範囲において、印加電圧の逆数と液晶リターダの位相差との線形制御を可能にする。 Also, a method of driving a liquid crystal retarder that electrically changes the polarization state of light by utilizing the birefringence of a substance having optical anisotropy has been proposed (see Patent Document 3). This driving method enables linear control of the reciprocal of the applied voltage and the phase difference of the liquid crystal retarder in the range where the applied voltage V to the liquid crystal retarder is larger than the threshold voltage Vth.
米国特許第８３０５５２３号US Patent No. 8305523 米国特許第８９８２３１３号US Pat. No. 8,982,313 特許第３５２９６９９号公報Japanese Patent No. 3529699
　リターダの個体差、経年劣化、使用時の温度変化等の影響により、リターダ個々において位相遅れ量が変化することにより、位相遅れ量が所望の値に設定されなくなる場合がある。この場合、所望の偏光状態の光をリターダから出射することができない、という問題がある。 -The phase delay amount may not be set to the desired value due to the phase delay amount changing in each retarder due to the individual difference of the retarder, deterioration over time, temperature change during use, etc. In this case, there is a problem in that the light of the desired polarization state cannot be emitted from the retarder.
　本開示は、リターダの位相遅れ量を正確に制御することができる偏光状態の制御技術を提供することを目的とする。 The present disclosure aims to provide a polarization state control technique capable of accurately controlling the phase delay amount of a retarder.
　本開示の技術の第１の態様である偏光状態制御装置は、直線偏光子、リターダ、反射板、受光部、及び制御部を含んで構成されている。前記直線偏光子は、光源光を直線偏光に偏光する。前記リターダは、前記直線偏光子を通過した光源光が入射されると共に、印加される電圧に応じて、入射された光の偏光状態を変えて出射する。前記反射板は、前記直線偏光子を通過した光源光の一部を、前記リターダの出射面側において入射面側に反射させる。前記受光部は、前記反射板により反射されて、前記直線偏光子を通過した光を受光する。前記制御部は、前記受光部により受光された光の光量に基づいて、前記入射された光をλ／２又は０の位相遅れで偏光した光が前記リターダから出射されるように、前記リターダに印加する電圧を制御する。 The polarization state control device according to the first aspect of the technology of the present disclosure is configured to include a linear polarizer, a retarder, a reflection plate, a light receiving unit, and a control unit. The linear polarizer polarizes the source light into linearly polarized light. The light source light that has passed through the linear polarizer is incident on the retarder, and the retarder changes the polarization state of the incident light according to the applied voltage and emits the light. The reflection plate reflects a part of the light source light that has passed through the linear polarizer toward the incident surface side on the exit surface side of the retarder. The light receiving unit receives the light reflected by the reflecting plate and passing through the linear polarizer. The control unit controls the retarder so that light obtained by polarizing the incident light with a phase delay of λ/2 or 0 is emitted from the retarder based on the amount of light received by the light receiving unit. Control the applied voltage.
　上記第１の態様である偏光状態制御装置によれば、光源光を直線偏光に偏光する直線偏光子を通過した光源光がリターダに入射される。リターダは、印加される電圧に応じて、入射された光の偏光状態を変えて出射する。また、反射板が、直線偏光子を通過した光源光の一部を、リターダの出射面側において入射面側に反射させる。反射板により反射されて、直線偏光子を通過した光は受光部で受光される。 According to the polarization state control device of the first aspect, the light source light that has passed through the linear polarizer that polarizes the light source light into linearly polarized light is incident on the retarder. The retarder changes the polarization state of the incident light according to the applied voltage and emits the light. Further, the reflection plate reflects a part of the light source light that has passed through the linear polarizer toward the incident surface side on the exit surface side of the retarder. The light reflected by the reflecting plate and passing through the linear polarizer is received by the light receiving section.
　そして、上記第１の態様である偏光状態制御装置によれば、制御部が、受光部により受光された光の光量に基づいて、入射された光をλ／２又は０の位相遅れで偏光した光がリターダから出射されるように、リターダに印加する電圧を制御する。これにより、本開示の偏光状態制御装置は、リターダの位相遅れ量を正確に制御することができる。 Then, according to the polarization state control device of the first aspect, the control unit polarizes the incident light with a phase delay of λ/2 or 0 based on the light amount of the light received by the light receiving unit. The voltage applied to the retarder is controlled so that the light is emitted from the retarder. Accordingly, the polarization state control device of the present disclosure can accurately control the phase delay amount of the retarder.
　また、本開示の技術の第２の態様である偏光状態制御装置は、光が前記反射板で反射されない光路上であって、前記直線偏光子と前記リターダとの間に配置される１／４波長板をさらに含んで構成することができる。これにより、本開示の偏光状態制御装置は、リターダに円偏光の光が入射され、リターダの位相遅れ量が正確に制御されることにより、リターダから、所望の回転方向に制御された円偏光の光を出射することができる。 In addition, the polarization state control device that is the second aspect of the technology of the present disclosure is a quarter that is arranged on the optical path where light is not reflected by the reflection plate and between the linear polarizer and the retarder. A wave plate may be further included. Thus, the polarization state control device of the present disclosure, circularly polarized light is incident on the retarder, by accurately controlling the phase delay amount of the retarder, from the retarder of the circularly polarized light controlled in the desired rotation direction. Light can be emitted.
　また、本開示の技術の第３の態様である偏光状態制御装置は、光が前記反射板で反射される光路上であって、前記直線偏光子と前記リターダとの間に配置される１／４波長板をさらに含んで構成することができる。 The polarization state control device according to the third aspect of the technique of the present disclosure is arranged on the optical path where light is reflected by the reflection plate, and is disposed between the linear polarizer and the retarder. It can be configured to further include a four-wave plate.
　また、本開示の技術の第４の態様である偏光状態制御装置は、前記リターダから出射された光が入射される偏光グレーティングをさらに含んで構成することができる。前記偏光状態制御装置において、前記反射板は、前記偏光グレーティングへ入射される前の光を反射することができる。これにより、本開示の偏光状態制御装置は、リターダから偏光グレーティングへ入射される光の位相遅れ量が正確に制御されているため、偏光グレーティングから出射される光の回折効率を最大にすることができる。 The polarization state control device according to the fourth aspect of the technology of the present disclosure can be configured to further include a polarization grating on which the light emitted from the retarder is incident. In the polarization state control device, the reflection plate can reflect light that has not been incident on the polarization grating. Thereby, the polarization state control device of the present disclosure can accurately control the phase delay amount of the light incident from the retarder to the polarization grating, and thus maximize the diffraction efficiency of the light emitted from the polarization grating. it can.
　また、本開示の技術の第５の態様である偏光状態制御装置は、前記リターダと前記偏光グレーティングとの組み合わせを複数積層することができる。前記偏光状態制御装置において、前記反射板及び前記受光部は、前記組み合わせの各々に対応して設けられている。前記制御部は、前記受光部の各々により受光された光の光量に基づいて、前記受光部に対応する前記組み合わせを構成する前記リターダに印加する電圧を制御することができる。これにより、本開示の偏光状態制御装置は、リターダの位相遅れ量が個別に正確に制御されるため、複数の方向に正確に出射光を回折させることができる。 Further, the polarization state control device according to the fifth aspect of the technique of the present disclosure can stack a plurality of combinations of the retarder and the polarization grating. In the polarization state control device, the reflection plate and the light receiving unit are provided corresponding to each of the combinations. The control unit may control the voltage applied to the retarders that form the combination corresponding to the light receiving units, based on the amount of light received by each of the light receiving units. With this, the polarization state control device of the present disclosure can accurately control the phase delay amount of the retarder individually, and thus can accurately diffract the emitted light in a plurality of directions.
　また、本開示の技術の第６の態様である偏光状態制御装置において、前記制御部は、前記受光部により受光された光の光量が最大となるように、前記リターダに印加する電圧を制御することができる。これにより、本開示の偏光状態制御装置は、反射板で反射して再度リターダ及び直線偏光子を通過した光の光度を用いているため、光量が最大となる電圧値を、λ／２又は０の位相遅れ量を設定するための電圧値とすることができる。 Further, in the polarization state control device according to the sixth aspect of the technology of the present disclosure, the control unit controls the voltage applied to the retarder so that the amount of light received by the light receiving unit is maximized. be able to. Accordingly, the polarization state control device of the present disclosure uses the luminous intensity of the light reflected by the reflection plate and passed through the retarder and the linear polarizer again, so that the voltage value that maximizes the light amount is λ/2 or 0. Can be used as a voltage value for setting the amount of phase delay.
　また、本開示の技術の第７の態様である偏光状態制御装置において、前記直線偏光子は、入射方向へＰ偏光の光を出射し、前記入射方向と直交する方向へＳ偏光の光を出射する偏光ビームスプリッタである。前記受光部は、前記偏光ビームスプリッタから出射されるＳ偏光の光を受光し、前記制御部は、前記受光部で受光されたＳ偏光の光の光量が最小となるように、前記リターダに印加する電圧を制御することができる。これにより、本開示の偏光状態制御装置は、反射板で反射して再度リターダ及び偏光ビームスプリッタを通過したＳ偏光の光の光度を用いているため、光量が最小となる電圧値を、λ／２又は０の位相遅れ量を設定するための電圧値とすることができる。 Further, in the polarization state control device according to the seventh aspect of the technology of the present disclosure, the linear polarizer emits P-polarized light in an incident direction and emits S-polarized light in a direction orthogonal to the incident direction. It is a polarization beam splitter. The light receiving unit receives the S-polarized light emitted from the polarization beam splitter, and the control unit applies the light to the retarder so that the amount of the S-polarized light received by the light receiving unit is minimized. The voltage applied can be controlled. Accordingly, the polarization state control device of the present disclosure uses the luminous intensity of the S-polarized light that has been reflected by the reflection plate and passed through the retarder and the polarization beam splitter again, so that the voltage value that minimizes the light amount is λ/ It may be a voltage value for setting the phase delay amount of 2 or 0.
　また、本開示の技術の第８の態様である偏光状態制御装置において、前記制御部は、予め設定された、前記リターダに印加する電圧に対する位相遅れ量の特性において、所定の電圧値より低い電圧値の第１数値範囲において、位相遅れ量がλ／２となる電圧値を探索し、前記所定の電圧値より高い電圧値の第２数値範囲において、位相遅れ量が０となる電圧値を探索することができる。また、本開示の技術の第９の態様である偏光状態制御装置において、前記制御部は、予め設定された、前記リターダに印加する電圧に対する位相遅れ量の特性において、λ／２又は０の位相遅れ量に対応する電圧値の近傍で、前記リターダに印加する電圧値を探索してもよい。これにより、本開示の偏光状態制御装置は、位相遅れ量のλ／２に対応する電圧値と、位相遅れ量の０に対応する電圧値と、を正確に探索することができる。 Further, in the polarization state control device which is the eighth aspect of the technology of the present disclosure, the control unit has a preset characteristic of the amount of phase delay with respect to the voltage applied to the retarder, which is lower than a predetermined voltage value. In the first numerical range of values, a voltage value with a phase delay amount of λ/2 is searched for, and in a second numerical value range of voltage values higher than the predetermined voltage value, a voltage value with a phase delay amount of 0 is searched for. can do. Further, in the polarization state control device which is the ninth aspect of the technology of the present disclosure, the control unit has a phase characteristic of λ/2 or 0 in a preset characteristic of a phase delay amount with respect to a voltage applied to the retarder. The voltage value applied to the retarder may be searched in the vicinity of the voltage value corresponding to the delay amount. Accordingly, the polarization state control device of the present disclosure can accurately search for a voltage value corresponding to the phase delay amount λ/2 and a voltage value corresponding to the phase delay amount 0.
　また、本開示の技術の他の態様である偏光状態制御方法は、上記偏光状態制御装置が提供する機能を実現するための方法である。また、本開示の技術の他の態様である偏光状態制御プログラムは、上記偏光状態制御方法を実行するためのプログラムであり、コンピュータを、上記偏光状態制御装置の制御部として機能させるためのプログラムである。また、本開示の技術の他の態様である記録媒体は、上記偏光状態制御プログラムを記録した記録媒体である。 A polarization state control method that is another aspect of the technology of the present disclosure is a method for realizing the function provided by the polarization state control device. A polarization state control program that is another aspect of the technology of the present disclosure is a program for executing the polarization state control method, and is a program for causing a computer to function as a control unit of the polarization state control device. is there. A recording medium that is another aspect of the technique of the present disclosure is a recording medium that records the above-mentioned polarization state control program.
　本開示の技術によれば、反射板により反射されて再度リターダ及び直線偏光子を通過した光の光量に基づいて、リターダの位相遅れ量がλ／２又は０になるように、リターダに印加する電圧を制御する。これにより、本開示の技術は、リターダの位相遅れ量を正確に制御することができる。 According to the technology of the present disclosure, the retarder and the linear polarizer are applied to the retarder so that the phase delay amount becomes λ/2 or 0 based on the light amount of the light that has passed through the retarder and the linear polarizer again. Control the voltage. Accordingly, the technique of the present disclosure can accurately control the phase delay amount of the retarder.
　本開示についての上記目的及びその他の目的、特徴や利点は、添付の図面を参照しながら下記の詳細な記述により、より明確になる。
第１実施形態に係る偏光状態制御装置の構成を示す概略図である。 制御部の機能ブロック図である。 電圧と光量との関係の一例を示す図である。 光量と位相遅れ量との関係を説明するための図である。 電圧－位相遅れ量特性の一例を示す図である。 偏光状態制御処理の一例を示すフローチャートである。 第２実施形態に係る偏光状態制御装置の構成を示す概略図である。 第３実施形態に係る偏光状態制御装置の構成を示す概略図である。 第４実施形態に係る偏光状態制御装置の構成を示す概略図である。 第５実施形態に係る偏光状態制御装置の構成を示す概略図である。 光量と位相遅れ量との関係を説明するための図である。 第６実施形態に係る偏光状態制御装置の構成を示す概略図である。 電圧－位相遅れ量特性の温度変化を説明するための図である。 The above and other objects, features and advantages of the present disclosure will become more apparent by the following detailed description with reference to the accompanying drawings.
It is a schematic diagram showing the composition of the polarization control device concerning a 1st embodiment. It is a functional block diagram of a control part. It is a figure which shows an example of the relationship between a voltage and a light quantity. It is a figure for demonstrating the relationship between the amount of light and the amount of phase delays. It is a figure which shows an example of a voltage-phase delay amount characteristic. It is a flow chart which shows an example of polarization state control processing. It is a schematic diagram showing composition of a polarization control device concerning a 2nd embodiment. It is a schematic diagram showing composition of a polarization control device concerning a 3rd embodiment. It is a schematic diagram showing composition of a polarization control device concerning a 4th embodiment. It is a schematic diagram showing composition of a polarization control device concerning a 5th embodiment. It is a figure for demonstrating the relationship between the amount of light and the amount of phase delays. It is a schematic diagram showing composition of a polarization control device concerning a 6th embodiment. FIG. 6 is a diagram for explaining a temperature change of a voltage-phase delay amount characteristic.
　以下、図面を参照して本開示の技術の実施形態を詳細に説明する。 Hereinafter, embodiments of the technology of the present disclosure will be described in detail with reference to the drawings.
＜第１実施形態＞
　図１に示すように、第１実施形態に係る偏光状態制御装置１０は、直線偏光子１２と、リターダ１４と、ミラー１６と、受光部１８と、制御部２０と、制御用電源２２と、第１及び第２電極２４Ｌ，２４Ｒと、を含んで構成される。 <First Embodiment>
As shown in FIG. 1, the polarization state control device 10 according to the first embodiment includes a linear polarizer 12, a retarder 14, a mirror 16, a light receiving unit 18, a control unit 20, a control power supply 22, and The first and second electrodes 24L and 24R are included.
　直線偏光子１２は、レーザ光源２６から出射された光（Ｌ１）を直線偏光の光（Ｌ２）に偏光して出射する。 The linear polarizer 12 polarizes the light (L1) emitted from the laser light source 26 into linearly polarized light (L2) and emits it.
　リターダ１４は、λ／２板であり、一部に制御用電源２２と接続された第１及び第２電極２４Ｌ，２４Ｒが設けられている。なお、λ／２板は、直線偏光の偏光方向を回転させる１／２波長板である。リターダ１４は、直線偏光子１２から出射した光（Ｌ２）が入射されると共に、印加される電圧に応じて、入射された光の偏光状態を変えた光（Ｌ３）を出射する。 The retarder 14 is a λ/2 plate, and is provided with first and second electrodes 24L and 24R partially connected to the control power supply 22. The λ/2 plate is a ½ wavelength plate that rotates the polarization direction of linearly polarized light. The retarder 14 receives the light (L2) emitted from the linear polarizer 12 and also emits the light (L3) in which the polarization state of the incident light is changed according to the applied voltage.
　ミラー１６は、本開示の技術における反射板の一例である。ミラー１６は、リターダ１４の出射面Ｓｏ側に設けられており、直線偏光子１２から出射した光の一部（Ｌ４）を、リターダ１４の出射面Ｓｏ側において入射面Ｓｉ側に反射させる。直線偏光子１２から出射した光の一部は、リターダ１４の入射面Ｓｉから入射し、出射面Ｓｏ側に設けられたミラー１６の反射面に到達する。その結果、ミラー１６により反射された光（反射光）は、リターダ１４の出射面Ｓｏ側から入射面Ｓｉ側に進む。 Mirror 16 is an example of a reflector in the technique of the present disclosure. The mirror 16 is provided on the emission surface So side of the retarder 14, and reflects a part (L4) of the light emitted from the linear polarizer 12 to the incidence surface Si side on the emission surface So side of the retarder 14. Part of the light emitted from the linear polarizer 12 enters from the incident surface Si of the retarder 14 and reaches the reflecting surface of the mirror 16 provided on the exit surface So side. As a result, the light (reflected light) reflected by the mirror 16 travels from the exit surface So side of the retarder 14 to the entrance surface Si side.
　受光部１８は、ミラー１６により反射されて、直線偏光子１２を通過した光（Ｌ５）を受光し、受光した光の光量を示す光量データを出力する。受光部１８は、例えば光量モニタである。 The light receiving unit 18 receives the light (L5) reflected by the mirror 16 and passing through the linear polarizer 12, and outputs the light amount data indicating the light amount of the received light. The light receiving unit 18 is, for example, a light amount monitor.
　制御部２０は、ＣＰＵ（Central　Processing　Unit）と、ＲＡＭ（Random　Access　Memory）と、ＲＯＭ（Read　Only　Memory）と、を備えたコンピュータにより実現することができる。第１実施形態では、ＣＰＵが偏光状態制御プログラムを実行することにより、コンピュータが偏光状態制御装置１０の制御部２０として機能することになる。また、例えばＲＯＭには、後述する偏光状態制御処理を実行するための偏光状態制御プログラムが記憶されている。なお、本開示の技術では、ＲＯＭが、プログラムを記録した記録媒体の一例である。 The control unit 20 can be realized by a computer including a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory). In the first embodiment, the computer functions as the control unit 20 of the polarization state control device 10 by the CPU executing the polarization state control program. Further, for example, the ROM stores a polarization state control program for executing a polarization state control process described later. In the technique of the present disclosure, the ROM is an example of a recording medium that records the program.
　図２に示すように、制御部２０は、光量取得部４２と、電圧値決定部４４と、電圧制御部４６と、ＤＢ（database）４８と、を含んで構成される。 As shown in FIG. 2, the control unit 20 includes a light amount acquisition unit 42, a voltage value determination unit 44, a voltage control unit 46, and a DB (database) 48.
　光量取得部４２は、受光部１８から出力された光量データを取得し、電圧値決定部４４に受け渡す。 The light amount acquisition unit 42 acquires the light amount data output from the light receiving unit 18, and transfers it to the voltage value determination unit 44.
　電圧値決定部４４は、光量取得部４２から受け渡された光量データに基づいて、リターダ１４に入射された光がλ／２又は０の位相遅れで偏光されてリターダ１４から出射されるように、リターダ１４に印加する電圧値を決定する。 The voltage value determination unit 44 causes the light incident on the retarder 14 to be polarized with a phase delay of λ/2 or 0 and to be emitted from the retarder 14 based on the light amount data passed from the light amount acquisition unit 42. , The voltage value applied to the retarder 14 is determined.
　図３に、リターダ１４に印加する電圧と、受光部１８から取得される光量と、の関係の一例を概略的に示す。電圧値決定部４４は、図３に示すように、位相遅れ量がλ／２又は０となる電圧値として、光量取得部４２から受け渡された光量データが示す光量が最大となる電圧値を決定する。 FIG. 3 schematically shows an example of the relationship between the voltage applied to the retarder 14 and the light amount obtained from the light receiving unit 18. As shown in FIG. 3, the voltage value determination unit 44 sets the voltage value at which the light amount indicated by the light amount data passed from the light amount acquisition unit 42 becomes the maximum voltage value as the voltage value at which the phase delay amount becomes λ/2 or 0. decide.
　ここで、第１実施形態において、リターダ１４の位相遅れ量がλ／２又は０の場合に、直線偏光子１２からの出射光の光量が最大になる原理について説明する。 Here, in the first embodiment, the principle that the amount of light emitted from the linear polarizer 12 is maximized when the phase delay amount of the retarder 14 is λ/2 or 0 will be described.
　まず、リターダ１４の位相遅れ量がλ／２（１／２波長）の場合、図４に示すように、リターダ１４がλ／２板として動作する。このため、直線偏光の偏波面とリターダ１４の速軸とのなす角度がθの場合、リターダ１４を一回通過した後、偏波面と速軸とのなす角度は２θになる。入射光の偏光方向がλ／２板の速軸に対してθの方位角で入射した場合、リターダ１４は、入射光の偏光方向を２θ回転させて出射する。つまり、入射光の偏波面が速軸に対して折り返した位置に変わる。リターダ１４からの出射光がミラー１６によって反射されて再度リターダ１４を通過した場合、同様の原理によって、リターダ１４からの出射光の偏波面が速軸に対して折り返した位置に変わる。つまり、出射光の偏波面が元の位置に戻ることになる。したがって、第１実施形態の構成では、出射光の偏波面と直線偏光子１２の通過軸とが一致する。そのため、直線偏光子１２からの出射光の光量が最大になる。 First, when the phase delay amount of the retarder 14 is λ/2 (1/2 wavelength), the retarder 14 operates as a λ/2 plate as shown in FIG. Therefore, when the angle between the plane of polarization of linearly polarized light and the fast axis of the retarder 14 is θ, the angle between the plane of polarization and the fast axis becomes 2θ after passing through the retarder 14 once. When the polarization direction of the incident light is incident at an azimuth angle of θ with respect to the fast axis of the λ/2 plate, the retarder 14 rotates the polarization direction of the incident light by 2θ and emits it. That is, the plane of polarization of the incident light changes to a position folded back with respect to the fast axis. When the light emitted from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again, the polarization plane of the light emitted from the retarder 14 changes to a position folded back with respect to the fast axis by the same principle. That is, the polarization plane of the emitted light returns to the original position. Therefore, in the configuration of the first embodiment, the plane of polarization of the emitted light and the pass axis of the linear polarizer 12 match. Therefore, the amount of light emitted from the linear polarizer 12 is maximized.
　また、リターダ１４の位相遅れ量が０の場合、リターダ１４を通過した後においても直線偏光の偏波面は変わらない。さらに、リターダ１４からの出射光がミラー１６によって反射されて再度リターダ１４を通過した後も、出射光の偏波面は変わらない。したがって、第１実施形態の構成では、出射光の偏波面と直線偏光子１２の通過軸とが一致する。そのため、直線偏光子１２からの出射光の光量が最大になる。 Moreover, when the phase delay amount of the retarder 14 is 0, the polarization plane of the linearly polarized light does not change even after passing through the retarder 14. Further, the polarization plane of the emitted light does not change even after the emitted light from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again. Therefore, in the configuration of the first embodiment, the plane of polarization of the emitted light and the pass axis of the linear polarizer 12 match. Therefore, the amount of light emitted from the linear polarizer 12 is maximized.
　電圧値決定部４４は、リターダ１４に印加する電圧値を決定する。具体的には、電圧値決定部４４は、リターダ１４に印加する電圧を変化させながら、所定の探索範囲内（数値範囲内）を探索して、探索結果を基に光量が最大となる電圧値を決定する。電圧値決定部４４は、ＤＢ４８を参照して、所定の探索範囲を決定する。 The voltage value determination unit 44 determines the voltage value applied to the retarder 14. Specifically, the voltage value determination unit 44 searches the predetermined search range (within the numerical range) while changing the voltage applied to the retarder 14, and the voltage value that maximizes the light amount based on the search result. To decide. The voltage value determination unit 44 determines a predetermined search range with reference to the DB 48.
　ＤＢ４８は、リターダ１４に印加する電圧に対する位相遅れ量の特性（以下「電圧－位相遅れ量特性」という）が記憶されたデータベースである。例えば、リターダ１４の使用開始時などに、印加する電圧を変えながら位相遅れ量を計測し、電圧値と計測値とに基づき、電圧－位相遅れ量特性を示すデータを記憶しておくことができる。図５に、ＤＢ４８に記憶される電圧－位相遅れ量特性の一例を示す。 The DB 48 is a database in which the characteristics of the phase delay amount with respect to the voltage applied to the retarder 14 (hereinafter referred to as “voltage-phase delay amount characteristics”) are stored. For example, when the retarder 14 starts to be used, the phase delay amount is measured while changing the applied voltage, and the data indicating the voltage-phase delay amount characteristic can be stored based on the voltage value and the measured value. .. FIG. 5 shows an example of the voltage-phase delay amount characteristic stored in the DB 48.
　図５に示すように、電圧－位相遅れ量特性は、単調減少曲線を示す。そこで、電圧値決定部４４は、ＤＢ４８に記憶された電圧－位相遅れ量特性において、位相遅れ量がλ／２になる電圧値と０になる電圧値との間の任意の電圧値を閾値として設定する。そして、電圧値決定部４４は、設定した閾値より低い電圧値の数値範囲（第１数値範囲）を探索範囲（第１探索範囲）として、位相遅れ量がλ／２となる電圧値を探索する。また、電圧値決定部４４は、設定した閾値より高い電圧値の数値範囲（第２数値範囲）を探索範囲（第２探索範囲）として、位相遅れ量が０となる電圧値を探索する。なお、この場合、図５に示すような電圧－位相遅れ量特性に代えて、所定の閾値となる電圧値のみを記憶しておいてもよい。 As shown in FIG. 5, the voltage-phase delay amount characteristic shows a monotonically decreasing curve. Therefore, in the voltage-phase delay amount characteristic stored in the DB 48, the voltage value determination unit 44 sets an arbitrary voltage value between the voltage value at which the phase delay amount becomes λ/2 and the voltage value at which the phase delay amount becomes 0 as a threshold value. Set. Then, the voltage value determination unit 44 searches for a voltage value at which the phase delay amount is λ/2, with the numerical value range (first numerical value range) of the voltage value lower than the set threshold value as the search range (first search range). .. Further, the voltage value determination unit 44 searches for a voltage value at which the phase delay amount is 0, with the numerical range (second numerical range) of the voltage value higher than the set threshold value as the search range (second search range). In this case, instead of the voltage-phase delay amount characteristic as shown in FIG. 5, only the voltage value serving as the predetermined threshold value may be stored.
　また、電圧値決定部４４は、電圧－位相遅れ量特性において、λ／２又は０の位相遅れ量に対応する電圧値の近傍、例えばその電圧値を含む前後の所定の電圧値の数値範囲を探索範囲として、位相遅れ量がλ／２又は０になる電圧値を探索してもよい。なお、この場合、図５に示すような電圧－位相遅れ量特性に代えて、λ／２及び０の位相遅れ量に対応する電圧値のみを記憶しておいてもよい。 In the voltage-phase delay amount characteristic, the voltage value determination unit 44 sets the vicinity of the voltage value corresponding to the phase delay amount of λ/2 or 0, for example, the numerical value range of a predetermined voltage value before and after including the voltage value. As the search range, a voltage value at which the phase delay amount becomes λ/2 or 0 may be searched. In this case, instead of the voltage-phase delay amount characteristic shown in FIG. 5, only the voltage values corresponding to the phase delay amounts of λ/2 and 0 may be stored.
　電圧値決定部４４は、上記のように電圧値の探索範囲を設定することで、図３に示すような電圧と光量との関係において、位相遅れ量がλ／２になる電圧値と、０になる電圧値と、を正確に探索することができる。 The voltage value determination unit 44 sets the voltage value search range as described above, and in the relationship between the voltage and the light amount as shown in FIG. It is possible to accurately search for
　電圧値決定部４４は、決定した電圧値を電圧制御部４６へ受け渡す。 The voltage value determination unit 44 transfers the determined voltage value to the voltage control unit 46.
　電圧制御部４６は、電圧値決定部４４から受け渡された電圧値を制御用電源２２に設定する。 The voltage control unit 46 sets the voltage value transferred from the voltage value determination unit 44 in the control power supply 22.
　制御用電源２２は、設定された電圧値の電圧を、第１及び第２電極２４Ｌ，２４Ｒを介してリターダ１４に印加する。第１実施形態では、制御用電源２２がリターダ１４の位相遅れ量がλ／２又は０に設定されるように電圧を印加し、リターダ１４から出射される光（Ｌ３）の直線偏光の偏波面が所望の方向に切り替えられる。このとき、第１実施形態では、電圧制御部４６は、λ／２又は０の位相遅れで偏光した光がリターダ１４から出射されるように、リターダ１４に印加する電圧を制御する。 The control power supply 22 applies the voltage of the set voltage value to the retarder 14 via the first and second electrodes 24L and 24R. In the first embodiment, the control power supply 22 applies a voltage so that the phase delay amount of the retarder 14 is set to λ/2 or 0, and the polarization plane of the linearly polarized light (L3) emitted from the retarder 14 Can be switched to the desired direction. At this time, in the first embodiment, the voltage controller 46 controls the voltage applied to the retarder 14 so that the light polarized with the phase delay of λ/2 or 0 is emitted from the retarder 14.
　次に、第１実施形態に係る偏光状態制御装置１０の作用について説明する。 Next, the operation of the polarization state control device 10 according to the first embodiment will be described.
　レーザ光源２６から出射されたレーザ光の一部（Ｌ１）は、直線偏光子１２に入射され、直線偏光子１２によって直線偏光される。直線偏光された光（Ｌ２）は、直線偏光子１２から出射され、リターダ１４に入射される。そして、リターダ１４は、当該リターダ１４に設定された位相遅れ量に応じて、入射された光の偏光状態を変化させ、偏光された光（Ｌ３）を出射する。 A part (L1) of the laser light emitted from the laser light source 26 enters the linear polarizer 12 and is linearly polarized by the linear polarizer 12. The linearly polarized light (L2) is emitted from the linear polarizer 12 and is incident on the retarder 14. Then, the retarder 14 changes the polarization state of the incident light according to the phase delay amount set in the retarder 14 and emits the polarized light (L3).
　一方、レーザ光源２６から出射されたレーザ光の一部（Ｌ２０）は、直線偏光子１２に入射され、直線偏光子１２によって直線偏光される。直線偏光された光（Ｌ４）は、直線偏光子１２から出射され、リターダ１４に入射される。リターダ１４の出射面Ｓｏまで到達した光は、ミラー１６の反射面によって反射される。反射された光は、リターダ１４及び直線偏光子１２を再び通過して（Ｌ５）、受光部１８で受光される。 On the other hand, a part (L20) of the laser light emitted from the laser light source 26 enters the linear polarizer 12 and is linearly polarized by the linear polarizer 12. The linearly polarized light (L4) is emitted from the linear polarizer 12 and is incident on the retarder 14. The light reaching the emission surface So of the retarder 14 is reflected by the reflection surface of the mirror 16. The reflected light passes through the retarder 14 and the linear polarizer 12 again (L5), and is received by the light receiving unit 18.
　受光部１８は、受光した光の光量を示す光量データを出力する。そして、制御部２０は、図６に示す偏光状態制御処理を実行する。これにより、リターダ１４の位相遅れ量は、λ／２又は０に設定される。 The light receiving unit 18 outputs light amount data indicating the light amount of the received light. Then, the control unit 20 executes the polarization state control process shown in FIG. As a result, the phase delay amount of the retarder 14 is set to λ/2 or 0.
　図６に示すように、第１実施形態に係る偏光状態制御処理のステップＳ１２において、電圧値決定部４４は、ＤＢ４８に記憶された電圧－位相遅れ量特性に関するデータを参照し、所定の閾値より低い電圧値の数値範囲を、位相遅れ量がλ／２となる電圧値を探索する探索範囲として設定する。また、電圧値決定部４４は、所定の閾値より高い電圧値の数値範囲を、位相遅れ量が０となる電圧値を探索する探索範囲として設定する。 As shown in FIG. 6, in step S12 of the polarization state control process according to the first embodiment, the voltage value determination unit 44 refers to the data regarding the voltage-phase delay amount characteristic stored in the DB 48, and determines that the predetermined threshold value is exceeded. The numerical value range of the low voltage value is set as the search range for searching the voltage value where the phase delay amount is λ/2. In addition, the voltage value determination unit 44 sets a numerical value range of voltage values higher than a predetermined threshold value as a search range for searching for a voltage value with a phase delay amount of 0.
　なお、電圧値決定部４４は、電圧－位相遅れ量特性において、λ／２又は０の位相遅れ量に対応する電圧値の近傍、例えばその電圧値を含む前後の所定の電圧値の数値範囲を探索範囲として設定してもよい。 In the voltage-phase delay amount characteristic, the voltage value determining unit 44 sets the vicinity of the voltage value corresponding to the phase delay amount of λ/2 or 0, for example, the numerical value range of a predetermined voltage value before and after including the voltage value. You may set as a search range.
　次に、ステップＳ１４において、電圧値決定部４４は、ステップＳ１２の処理によって設定された探索範囲内の初期値（最初の探索値）に相当する電圧値（例えば数値範囲内の最小の電圧値）を電圧制御部４６に出力する。電圧制御部４６は、電圧値決定部４４から入力された電圧値を制御用電源２２に設定する。 Next, in step S14, the voltage value determination unit 44 causes the voltage value corresponding to the initial value (first search value) within the search range set by the process of step S12 (for example, the minimum voltage value within the numerical range). Is output to the voltage control unit 46. The voltage control unit 46 sets the voltage value input from the voltage value determination unit 44 in the control power supply 22.
　次に、ステップＳ１６において、制御用電源２２は、設定された電圧値の電圧を、第１及び第２電極２４Ｌ，２４Ｒを介してリターダ１４に印加する。光量取得部４２は、制御用電源２２が電圧を印加した際に、受光部１８から出力される光量データを取得する。 Next, in step S16, the control power supply 22 applies the voltage having the set voltage value to the retarder 14 via the first and second electrodes 24L and 24R. The light amount acquisition unit 42 acquires the light amount data output from the light receiving unit 18 when the control power supply 22 applies a voltage.
　次に、ステップＳ１８において、電圧値決定部４４は、ステップＳ１４の処理によって設定された電圧値と、ステップＳ１６の処理によって取得された光量と、を一組のデータとして記憶する。 Next, in step S18, the voltage value determination unit 44 stores the voltage value set by the process of step S14 and the light amount acquired by the process of step S16 as a set of data.
　次に、ステップＳ２０において、電圧値決定部４４は、ステップＳ１２の処理によって設定された探索範囲内の電圧値に対して、ステップＳ１６及びＳ１８の処理が終了したか否かを判定する（探索終了を判定する）。探索範囲内に未処理の電圧値が存在する場合（探索が終了していない場合）には、ステップＳ２２へ移行する。ステップＳ２２において、電圧値決定部４４は、電圧値を所定値分ずらした値（電圧値を所定値分増減した値）に変更して設定し、ステップＳ１６に戻る。一方、探索範囲内に未処理の電圧値が存在しない場合（探索が終了した場合）には、ステップＳ２４へ移行する。 Next, in step S20, the voltage value determination unit 44 determines whether or not the processes of steps S16 and S18 have been completed for the voltage values within the search range set by the process of step S12 (end of search). Is determined). When there is an unprocessed voltage value within the search range (when the search is not completed), the process proceeds to step S22. In step S22, the voltage value determination unit 44 changes and sets the voltage value to a value shifted by a predetermined value (a value obtained by increasing or decreasing the voltage value by a predetermined value), and then returns to step S16. On the other hand, when there is no unprocessed voltage value in the search range (when the search is completed), the process proceeds to step S24.
　ステップＳ２４において、電圧値決定部４４は、ステップＳ１８の処理によって記憶された電圧値と光量との組データのうち、光量が最大となる組データの電圧値を、λ／２又は０の位相遅れ量に対応する電圧値として決定する。電圧値決定部４４は、決定した電圧値を電圧制御部４６に出力する。そして、電圧制御部４６は、電圧値決定部４４から入力された電圧値を制御用電源２２に設定し、偏光状態制御処理は終了する。 In step S24, the voltage value determination unit 44 sets the voltage value of the group data having the maximum light amount, out of the group data of the voltage value and the light amount stored by the process of step S18, to the phase delay of λ/2 or 0. It is determined as the voltage value corresponding to the quantity. The voltage value determination unit 44 outputs the determined voltage value to the voltage control unit 46. Then, the voltage control unit 46 sets the voltage value input from the voltage value determination unit 44 in the control power supply 22, and the polarization state control process ends.
　以上説明したように、第１実施形態に係る偏光状態制御装置１０によれば、リターダ１４の出射面Ｓｏ側で反射し、再び直線偏光子１２を通過して出射された光の光量をモニタリングしている。そして、偏光状態制御装置１０は、モニタリング結果である光量に基づいて、光の光量が最大になるように、リターダ１４に印加する電圧を制御する。これにより、偏光状態制御装置１０は、リターダ１４の位相遅れ量をλ／２又は０に設定することができる。その結果、偏光状態制御装置１０は、図１に示すように、リターダ１４に直線偏光の光（Ｌ２）が入射した場合に、リターダ１４からの出射光の直線偏光の偏波面を所望の状態（偏光状態）に切り替える。偏光状態制御装置１０は、リターダ１４によって偏光状態が変えられた光（Ｌ３）を出射することができる。以上のように、第１実施形態に係る偏光状態制御装置１０は、リターダ１４の位相遅れ量を正確に制御することができる。 As described above, according to the polarization state control device 10 according to the first embodiment, the amount of light that is reflected by the exit surface So side of the retarder 14 and passes through the linear polarizer 12 again to be output is monitored. ing. Then, the polarization state control device 10 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light becomes maximum. Thereby, the polarization state control device 10 can set the phase delay amount of the retarder 14 to λ/2 or 0. As a result, as shown in FIG. 1, when the linearly polarized light (L2) is incident on the retarder 14, the polarization state control device 10 sets the polarization plane of the linearly polarized light of the light emitted from the retarder 14 to a desired state ( Switch to (polarization state). The polarization state control device 10 can emit the light (L3) whose polarization state has been changed by the retarder 14. As described above, the polarization state control device 10 according to the first embodiment can accurately control the phase delay amount of the retarder 14.
　第１実施形態の構成の使い方としては、例えば、リターダ１４に入射する直線偏光の偏波面とリターダ１４の速軸とのなす角度θを４５度に設定して、２θが９０度になるように設定する。この場合、入射光の偏波面が９０度回転することになる。よって、第１実施形態の構成では、例えば、偏波面が水平の直線偏光の光を、偏波面が垂直の直線偏光の光に切り替えることができる。 As the usage of the configuration of the first embodiment, for example, the angle θ formed by the polarization plane of the linearly polarized light incident on the retarder 14 and the fast axis of the retarder 14 is set to 45 degrees so that 2θ becomes 90 degrees. Set. In this case, the plane of polarization of the incident light is rotated by 90 degrees. Therefore, in the configuration of the first embodiment, for example, linearly polarized light having a horizontal polarization plane can be switched to linearly polarized light having a vertical polarization plane.
＜第２実施形態＞
　次に、第２実施形態について説明する。なお、第２実施形態に係る偏光状態制御装置において、第１実施形態に係る偏光状態制御装置１０と同様の構成については、同一符号を付して詳細な説明を省略する。 <Second Embodiment>
Next, a second embodiment will be described. In the polarization state control device according to the second embodiment, the same components as those of the polarization state control device 10 according to the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.
　図７に示すように、第２実施形態に係る偏光状態制御装置２１０は、第１実施形態に係る偏光状態制御装置１０の構成に加え、レーザ光源２６からの光がミラー１６で反射されない光路上であって、直線偏光子１２とリターダ１４との間に、λ／４板２８が配置される。なお、λ／４板２８は、直線偏光を円偏光に変換する１／４波長板である。 As shown in FIG. 7, in addition to the configuration of the polarization state control device 10 according to the first embodiment, the polarization state control device 210 according to the second embodiment has an optical path on which light from the laser light source 26 is not reflected by the mirror 16. The λ/4 plate 28 is arranged between the linear polarizer 12 and the retarder 14. The λ/4 plate 28 is a quarter wavelength plate that converts linearly polarized light into circularly polarized light.
　λ／４板２８は、直線偏光子１２から出射される直線偏光の光（Ｌ２）が入射されると共に、直線偏光の光を円偏光の光に変えて出射する（Ｌ６）。λ／４板２８から出射される円偏光の光の回転方向は、右回りであっても左回りであってもよい。 The λ/4 plate 28 receives the linearly polarized light (L2) emitted from the linear polarizer 12 and converts the linearly polarized light into circularly polarized light and emits it (L6). The rotation direction of the circularly polarized light emitted from the λ/4 plate 28 may be clockwise or counterclockwise.
　リターダ１４は、円偏光の光（Ｌ６）が入射されると、設定されたλ／２又は０の位相遅れ量に応じて、回転方向を右回り又は左回りとする円偏光の光（Ｌ７）を出射する。 When the circularly polarized light (L6) is incident on the retarder 14, the circularly polarized light (L7) is rotated clockwise or counterclockwise according to the set phase delay amount of λ/2 or 0. Is emitted.
　なお、リターダ１４の位相遅れ量がλ／２又は０の場合に、直線偏光子１２からの出射光の光量が最大になる原理、及び、制御部２０における偏光状態制御処理は、第１実施形態と同様であるため、説明を省略する。 The principle that the amount of light emitted from the linear polarizer 12 is maximized when the phase delay amount of the retarder 14 is λ/2 or 0, and the polarization state control process in the control unit 20 is the same as in the first embodiment. Since it is the same as, the description will be omitted.
　以上説明したように、第２実施形態に係る偏光状態制御装置２１０によれば、リターダ１４の出射面Ｓｏ側で反射し、再び直線偏光子１２を通過して出射された光の光量をモニタリングしている。そして、偏光状態制御装置２１０は、モニタリング結果である光量に基づいて、光の光量が最大になるように、リターダ１４に印加する電圧を制御する。これにより、偏光状態制御装置２１０は、リターダ１４の位相遅れ量をλ／２又は０に設定することができる。その結果、偏光状態制御装置２１０は、図７に示すように、リターダ１４に円偏光の光（Ｌ６）が入射した場合に、位相遅れ量に応じた、右回り又は左回りの円偏光の光（Ｌ７）を出射することができる。 As described above, according to the polarization state control device 210 according to the second embodiment, the amount of light that is reflected by the exit surface So side of the retarder 14 and passes through the linear polarizer 12 again to be output is monitored. ing. Then, the polarization state control device 210 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light becomes maximum. Accordingly, the polarization state control device 210 can set the phase delay amount of the retarder 14 to λ/2 or 0. As a result, as shown in FIG. 7, when the circularly polarized light (L6) is incident on the retarder 14, the polarization state control device 210 causes the clockwise or counterclockwise circularly polarized light depending on the phase delay amount. (L7) can be emitted.
＜第３実施形態＞
　次に、第３実施形態について説明する。なお、第３実施形態に係る偏光状態制御装置において、第２実施形態に係る偏光状態制御装置２１０と同様の構成については、同一符号を付して詳細な説明を省略する。 <Third Embodiment>
Next, a third embodiment will be described. In the polarization state control device according to the third embodiment, the same components as those of the polarization state control device 210 according to the second embodiment are designated by the same reference numerals and detailed description thereof will be omitted.
　図８に示すように、第３実施形態に係る偏光状態制御装置３１０は、第２実施形態に係る偏光状態制御装置２１０の構成に加え、リターダ１４から出射された光が入射される偏光グレーティング（偏光回折格子）３０をさらに含む。この構成において、ミラー１６は、リターダ１４の出射面Ｓｏ側であって、偏光グレーティング３０に入射する前の光を反射可能な位置に配置される。 As shown in FIG. 8, in addition to the configuration of the polarization state control device 210 according to the second embodiment, the polarization state control device 310 according to the third embodiment has a polarization grating (on which the light emitted from the retarder 14 enters). A polarization diffraction grating) 30 is further included. In this configuration, the mirror 16 is arranged on the exit surface So side of the retarder 14 and at a position capable of reflecting the light before entering the polarization grating 30.
　偏光グレーティング３０は、回転方向が右回り又は左回りの円偏光の光（Ｌ６）が入射された場合、設定された回折角度に応じて、入射された光を回折させて出射する（Ｌ８）。 When the circularly polarized light (L6) whose rotation direction is clockwise or counterclockwise is incident, the polarization grating 30 diffracts the incident light according to the set diffraction angle and emits it (L8).
　なお、リターダ１４の位相遅れ量がλ／２又は０の場合に、直線偏光子１２からの出射光の光量が最大になる原理、及び、制御部２０における偏光状態制御処理は、第１実施形態と同様であるため、説明を省略する。 The principle that the amount of light emitted from the linear polarizer 12 is maximized when the phase delay amount of the retarder 14 is λ/2 or 0, and the polarization state control process in the control unit 20 is the same as in the first embodiment. Since it is the same as, the description will be omitted.
　以上説明したように、第３実施形態に係る偏光状態制御装置３１０によれば、リターダ１４の出射面Ｓｏ側で反射し、再び直線偏光子１２を通過して出射された光の光量をモニタリングしている。そして、偏光状態制御装置３１０は、モニタリング結果である光量に基づいて、光の光量が最大になるように、リターダ１４に印加する電圧を制御する。これにより、偏光状態制御装置３１０は、リターダ１４の位相遅れ量をλ／２又は０に設定することができる。その結果、偏光状態制御装置３１０は、図８に示すように、リターダ１４に円偏光の光（Ｌ６）が入射した場合に、回折角度に応じて回折された光（Ｌ８）をリターダ１４から出射することができる。 As described above, according to the polarization state control device 310 according to the third embodiment, the light amount of the light reflected by the exit surface So side of the retarder 14 and passing through the linear polarizer 12 again is monitored. ing. Then, the polarization state control device 310 controls the voltage applied to the retarder 14 so that the light amount of the light becomes maximum based on the light amount as the monitoring result. Thereby, the polarization state control device 310 can set the phase delay amount of the retarder 14 to λ/2 or 0. As a result, as shown in FIG. 8, when the circularly polarized light (L6) enters the retarder 14, the polarization state control device 310 emits the light (L8) diffracted according to the diffraction angle from the retarder 14. can do.
　偏光グレーティング３０に入射する円偏光の光の回転方向が、正確に左回り又は右回りの円偏光であれば、偏光グレーティング３０による回折効率が最大になる。しかし、偏光グレーティング３０に入射する光が円偏光ではなく楕円偏光になると、回折効率が低下する。したがって、回折効率を最大にするために、リターダ１４からの出射光を正確に円偏光にする必要がある。 If the rotation direction of the circularly polarized light incident on the polarization grating 30 is exactly left-handed or right-handed circularly polarized light, the diffraction efficiency by the polarization grating 30 is maximized. However, when the light incident on the polarization grating 30 becomes elliptically polarized light instead of circularly polarized light, the diffraction efficiency decreases. Therefore, in order to maximize the diffraction efficiency, the light emitted from the retarder 14 needs to be accurately circularly polarized.
　第３実施形態の構成では、図８に示すように、位相遅れ量が正確にλ／２又は０に設定されたリターダ１４から出射された円偏光の光が偏光グレーティング３０に入射される。そのため、第３実施形態の構成では、回転方向が正確に左回り又は右回りの円偏光の光が入射される。これにより、第３実施形態の構成では、回折効率を最大にすることができる。 In the configuration of the third embodiment, as shown in FIG. 8, circularly polarized light emitted from the retarder 14 whose phase delay amount is accurately set to λ/2 or 0 is incident on the polarization grating 30. Therefore, in the configuration of the third embodiment, circularly polarized light whose rotation direction is exactly counterclockwise or clockwise is incident. Thereby, in the configuration of the third embodiment, the diffraction efficiency can be maximized.
＜第４実施形態＞
　次に、第４実施形態について説明する。なお、第４実施形態に係る偏光状態制御装置において、第３実施形態に係る偏光状態制御装置３１０と同様の構成については、同一符号を付して詳細な説明を省略する。 <Fourth Embodiment>
Next, a fourth embodiment will be described. In the polarization state control device according to the fourth embodiment, the same components as those of the polarization state control device 310 according to the third embodiment are designated by the same reference numerals and detailed description thereof will be omitted.
　図９に示すように、第４実施形態に係る偏光状態制御装置４１０は、第３実施形態に係る偏光状態制御装置３１０の構成に加え、レーザ光源２６からの光がミラー１６で反射される光路上であって、直線偏光子１２とリターダ１４との間に、λ／４板４２８が配置される。図９の例では、λ／４板４２８は、レーザ光源２６からの光がミラー１６で反射されない光路上であって、直線偏光子１２とリターダ１４との間に配置されるλ／４板（第２及び第３実施形態におけるλ／４板２８）と一体化された例を示している。 As shown in FIG. 9, in addition to the configuration of the polarization state control device 310 according to the third embodiment, the polarization state control device 410 according to the fourth embodiment includes the light from the laser light source 26 reflected by the mirror 16. A λ/4 plate 428 is arranged on the road between the linear polarizer 12 and the retarder 14. In the example of FIG. 9, the λ/4 plate 428 is located on the optical path where the light from the laser light source 26 is not reflected by the mirror 16 and between the linear polarizer 12 and the retarder 14 ( An example integrated with the λ/4 plate 28) in the second and third embodiments is shown.
　λ／４板４２８は、ミラー１６で反射し、再びリターダ１４を通過した円偏光の光（Ｌ９）が入射されると共に、円偏光の光を直線偏光の光に変えて出射する（Ｌ１０）。 The λ/4 plate 428 reflects the circularly polarized light (L9) that has passed through the retarder 14 again after being reflected by the mirror 16, and converts the circularly polarized light into linearly polarized light and emits the linearly polarized light (L10).
　ここで、第４実施形態において、リターダ１４の位相遅れ量がλ／２又は０の場合に、直線偏光子１２からの出射光の光量が最大になる原理について説明する。 Here, in the fourth embodiment, the principle that the amount of light emitted from the linear polarizer 12 is maximized when the phase delay amount of the retarder 14 is λ/2 or 0 will be described.
　まず、リターダ１４の位相遅れ量がλ／２の場合、リターダ１４がλ／２板として動作する。このため、リターダ１４からの出射光は、リターダ１４への入射光の円偏光の回転方向と逆の回転方向の円偏光になる。リターダ１４からの出射光がミラー１６によって反射されて再度リターダ１４を通過した場合、同様な原理によって、逆の回転方向の円偏光になる。つまり、ミラー１６で反射してリターダ１４から出射される光（Ｌ９）の円偏光の回転方向が、リターダ１４に入射された光の円偏光の状態に戻ることになる。 First, when the phase delay amount of the retarder 14 is λ/2, the retarder 14 operates as a λ/2 plate. Therefore, the light emitted from the retarder 14 becomes circularly polarized light in the rotation direction opposite to the rotation direction of the circularly polarized light of the incident light to the retarder 14. When the light emitted from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again, it becomes circularly polarized light in the opposite rotation direction by the same principle. That is, the rotation direction of the circularly polarized light of the light (L9) reflected by the mirror 16 and emitted from the retarder 14 returns to the circularly polarized state of the light incident on the retarder 14.
　さらに、ミラー１６で反射してリターダ１４から出射される光（Ｌ９）がλ／４板４２８に入射した場合、λ／４板４２８から出射される光（Ｌ１０）の偏波面と直線偏光子１２の通過軸とが一致する。そのため、直線偏光子１２からの出射光（Ｌ５）の光量が最大になる。 Further, when the light (L9) reflected by the mirror 16 and emitted from the retarder 14 enters the λ/4 plate 428, the polarization plane of the light (L10) emitted from the λ/4 plate 428 and the linear polarizer 12 Coincides with the passing axis of. Therefore, the amount of light emitted from the linear polarizer 12 (L5) is maximized.
　また、リターダ１４の位相遅れ量が０の場合、リターダ１４を通過した後においても、円偏光の回転方向は変わらない。また、リターダ１４からの出射光がミラー１６によって反射されて再度リターダ１４を通過した後も、円偏光の回転方向は変わらない。さらに、その円偏光がλ／４板４２８に入射した場合、λ／４板４２８からの出射光（Ｌ１０）の偏波面と直線偏光子１２の通過軸とが一致する。そのため、直線偏光子１２からの出射光（Ｌ５）の光量が最大になる。 Moreover, when the phase delay amount of the retarder 14 is 0, the rotation direction of circularly polarized light does not change even after passing through the retarder 14. Even after the light emitted from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again, the rotation direction of circularly polarized light does not change. Further, when the circularly polarized light is incident on the λ/4 plate 428, the plane of polarization of the emitted light (L10) from the λ/4 plate 428 and the pass axis of the linear polarizer 12 coincide with each other. Therefore, the amount of light emitted from the linear polarizer 12 (L5) is maximized.
　制御部２０における偏光状態制御処理は、第１実施形態と同様であるため、説明を省略する。 Since the polarization state control processing in the control unit 20 is the same as that in the first embodiment, the description will be omitted.
　以上説明したように、第４実施形態に係る偏光状態制御装置４１０によれば、リターダ１４の出射面Ｓｏ側で反射し、再び直線偏光子１２を通過して出射された光の光量をモニタリングしている。そして、偏光状態制御装置４１０は、モニタリング結果である光量に基づいて、光の光量が最大になるように、リターダ１４に印加する電圧を制御する。これにより、偏光状態制御装置４１０は、リターダ１４の位相遅れ量をλ／２又は０に設定することができる。その結果、偏光状態制御装置４１０は、図９に示すように、回転方向が正確に左回り又は右回りの円偏光の光（Ｌ６）を、偏光グレーティング３０に入射することができる。偏光状態制御装置４１０は、偏光グレーティング３０からの出射光（Ｌ８）の回折効率を最大にすることができる。 As described above, according to the polarization state control device 410 according to the fourth embodiment, the light amount of the light reflected by the exit surface So side of the retarder 14 and again emitted through the linear polarizer 12 is monitored. ing. Then, the polarization state control device 410 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light becomes maximum. Accordingly, the polarization state control device 410 can set the phase delay amount of the retarder 14 to λ/2 or 0. As a result, the polarization state control device 410 can cause circularly polarized light (L6) whose rotation direction is exactly left-handed or right-handed to enter the polarization grating 30, as shown in FIG. The polarization state control device 410 can maximize the diffraction efficiency of the light (L8) emitted from the polarization grating 30.
＜第５実施形態＞
　次に、第５実施形態について説明する。なお、第５実施形態に係る偏光状態制御装置において、第３実施形態に係る偏光状態制御装置３１０と同様の構成については、同一符号を付して詳細な説明を省略する。 <Fifth Embodiment>
Next, a fifth embodiment will be described. In the polarization state control device according to the fifth embodiment, the same components as those of the polarization state control device 310 according to the third embodiment are denoted by the same reference numerals and detailed description thereof will be omitted.
　図１０に示すように、第５実施形態に係る偏光状態制御装置５１０は、第３実施形態に係る偏光状態制御装置３１０の直線偏光子１２及び制御部２０に代えて、偏光ビームスプリッタ５１２及び制御部５２０を備える。 As shown in FIG. 10, the polarization state control device 510 according to the fifth exemplary embodiment includes a polarization beam splitter 512 and a control unit instead of the linear polarizer 12 and the control unit 20 of the polarization state control device 310 according to the third exemplary embodiment. The unit 520 is provided.
　偏光ビームスプリッタ５１２は、偏光ビームスプリッタ５１２へ入射される光（Ｌ１，Ｌ２０）の入射方向へＰ偏光の光（Ｌ１１，Ｌ１３）を出射する。偏光ビームスプリッタ５１２は、偏光ビームスプリッタ５１２への入射される光の入射方向と直交する方向へＳ偏光の光（Ｌ１２，Ｌ１４）を出射する。 The polarization beam splitter 512 emits P-polarized light (L11, L13) in the incident direction of the light (L1, L20) incident on the polarization beam splitter 512. The polarization beam splitter 512 emits S-polarized light (L12, L14) in a direction orthogonal to the incident direction of the light incident on the polarization beam splitter 512.
　受光部１８は、ミラー１６で反射された反射光（Ｌ１５）が偏光ビームスプリッタ５１２に入射され、Ｓ偏光として出射された光（Ｌ１７）を受光し、受光した光の光量を示す光量データを出力する。 The light receiving unit 18 receives the light (L17), which is the reflected light (L15) reflected by the mirror 16 and is incident on the polarization beam splitter 512 and is emitted as S-polarized light, and outputs light amount data indicating the light amount of the received light. To do.
　図２に示す制御部２０の構成と同様に、制御部５２０は、光量取得部４２と、電圧値決定部５４４と、電圧制御部４６と、電圧－位相遅れ量特性を記憶するＤＢ４８と、を含んで構成される。 Similar to the configuration of the control unit 20 illustrated in FIG. 2, the control unit 520 includes a light amount acquisition unit 42, a voltage value determination unit 544, a voltage control unit 46, and a DB 48 that stores a voltage-phase delay amount characteristic. It is configured to include.
　電圧値決定部５４４は、図１１に示すように、位相遅れ量がλ／２又は０となる電圧値として、光量取得部４２から受け渡された光量データが示す光量が最小となる電圧値を決定する。 As shown in FIG. 11, the voltage value determination unit 544 sets the voltage value at which the amount of light indicated by the light amount data passed from the light amount acquisition unit 42 becomes the minimum voltage value as the voltage value at which the phase delay amount becomes λ/2 or 0. decide.
　ここで、第５実施形態において、リターダ１４の位相遅れ量がλ／２又は０の場合に、偏光ビームスプリッタ５１２からの出射光（Ｓ偏光）の光量が最小になる原理について説明する。 Here, in the fifth embodiment, the principle that the amount of light emitted from the polarization beam splitter 512 (S-polarized light) is minimized when the phase delay amount of the retarder 14 is λ/2 or 0 will be described.
　まず、リターダ１４の位相遅れ量がλ／２の場合、図４に示すように、リターダ１４がλ／２板として動作する。このため、直線偏光の偏波面とリターダ１４の速軸とのなす角度がθの場合、リターダ１４を一回通過した後、偏波面と速軸とのなす角度は２θになる。つまり、入射光の偏波面が速軸に対して折り返した位置に変わる。リターダ１４からの出射光がミラー１６によって反射されて再度リターダ１４を通過した場合、同様の原理によって、リターダ１４からの出射光の偏波面が速軸に対して折り返した位置に変わる。つまり、出射光の偏波面が元の位置に戻ることになる。したがって、第５実施形態の構成では、リターダ１４からの出射光はＰ偏光となる。そのため、偏光ビームスプリッタ５１２へ入射した場合、Ｓ偏光成分の光量は最小になる。 First, when the phase delay amount of the retarder 14 is λ/2, the retarder 14 operates as a λ/2 plate as shown in FIG. Therefore, when the angle between the plane of polarization of linearly polarized light and the fast axis of the retarder 14 is θ, the angle between the plane of polarization and the fast axis becomes 2θ after passing through the retarder 14 once. That is, the plane of polarization of the incident light changes to a position folded back with respect to the fast axis. When the light emitted from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again, the polarization plane of the light emitted from the retarder 14 changes to a position folded back with respect to the fast axis by the same principle. That is, the polarization plane of the emitted light returns to the original position. Therefore, in the configuration of the fifth embodiment, the light emitted from the retarder 14 becomes P-polarized light. Therefore, when the light is incident on the polarization beam splitter 512, the light amount of the S-polarized component becomes the minimum.
　また、リターダ１４の位相遅れ量が０の場合、リターダ１４を通過した後においてもＰ偏光は変わらない。さらに、リターダ１４からの出射光がミラー１６によって反射されて再度リターダ１４を通過した後も、出射光のＰ偏光は変わらない。したがって、第５実施形態の構成では、リターダ１４からの出射光はＰ偏光となる。そのため、偏光ビームスプリッタ５１２へ入射した場合、Ｓ偏光成分の光量は最小になる。 Also, when the phase delay amount of the retarder 14 is 0, the P-polarized light does not change even after passing through the retarder 14. Furthermore, the P-polarized light of the emitted light does not change even after the emitted light from the retarder 14 is reflected by the mirror 16 and passes through the retarder 14 again. Therefore, in the configuration of the fifth embodiment, the light emitted from the retarder 14 becomes P-polarized light. Therefore, when the light is incident on the polarization beam splitter 512, the light amount of the S-polarized component becomes the minimum.
　次に、第５実施形態に係る偏光状態制御装置５１０の作用について説明する。 Next, the operation of the polarization state control device 510 according to the fifth embodiment will be described.
　レーザ光源２６から出射されたレーザ光の一部（Ｌ１）は、偏光ビームスプリッタ５１２に入射され、偏光ビームスプリッタ５１２によって偏光される。Ｐ偏光の出射光（Ｌ１１）は入射方向へ出射され、Ｓ偏光の出射光（Ｌ１２）は入射方向に直交する方向に出射される。Ｐ偏光の出射光（Ｌ１１）は、λ／４板２８を介して円偏光に変換され、円偏光の光（Ｌ６）がリターダ１４に入射される。リターダ１４は、当該リターダ１４に設定された位相遅れ量に応じて、偏光された光を出射する。リターダ１４から出射された光は、偏光グレーティング３０に入射される。偏光グレーティング３０は、当該偏光グレーティング３０に設定された回折角度で回折された光（Ｌ８）を出射する。 A part (L1) of the laser light emitted from the laser light source 26 enters the polarization beam splitter 512 and is polarized by the polarization beam splitter 512. The P-polarized emitted light (L11) is emitted in the incident direction, and the S-polarized emitted light (L12) is emitted in the direction orthogonal to the incident direction. The P-polarized outgoing light (L11) is converted into circularly polarized light via the λ/4 plate 28, and the circularly polarized light (L6) is incident on the retarder 14. The retarder 14 emits polarized light according to the phase delay amount set in the retarder 14. The light emitted from the retarder 14 enters the polarization grating 30. The polarization grating 30 emits light (L8) diffracted at the diffraction angle set for the polarization grating 30.
　一方、レーザ光源２６から出射されたレーザ光の一部（Ｌ２０）は、偏光ビームスプリッタ５１２に入射され、偏光ビームスプリッタ５１２によって偏光される。Ｐ偏光の出射光（Ｌ１３）は入射方向へ出射され、Ｓ偏光の出射光（Ｌ１４）は入射方向に直交する方向に出射される。Ｐ偏光の出射光（Ｌ１３）はリターダ１４に入射される。リターダ１４の出射面Ｓｏまで到達した光は、ミラー１６の反射面によって反射される。反射された光は、再びリターダ１４を通過して、偏光ビームスプリッタ５１２へ入射される（Ｌ１５）。偏光ビームスプリッタ５１２は、Ｐ偏光の出射光（Ｌ１６）を入射方向に出射し、Ｓ偏光の出射光（Ｌ１７）を入射方向に直交する方向に出射する。 On the other hand, a part (L20) of the laser light emitted from the laser light source 26 enters the polarization beam splitter 512 and is polarized by the polarization beam splitter 512. The P-polarized emitted light (L13) is emitted in the incident direction, and the S-polarized emitted light (L14) is emitted in the direction orthogonal to the incident direction. The P-polarized outgoing light (L13) enters the retarder 14. The light reaching the emission surface So of the retarder 14 is reflected by the reflection surface of the mirror 16. The reflected light again passes through the retarder 14 and enters the polarization beam splitter 512 (L15). The polarization beam splitter 512 emits P-polarized outgoing light (L16) in the incident direction, and emits S-polarized outgoing light (L17) in the direction orthogonal to the incident direction.
　そして、受光部１８が、偏光ビームスプリッタ５１２からのＳ偏光の出射光（Ｌ１７）を受光し、受光した光の光量を示す光量データを出力する。そして、制御部５２０は、図６に示す偏光状態制御処理を実行する。これにより、リターダ１４の位相遅れ量は、λ／２又は０に設定される。 Then, the light receiving unit 18 receives the S-polarized outgoing light (L17) from the polarization beam splitter 512, and outputs light amount data indicating the light amount of the received light. Then, the control unit 520 executes the polarization state control process shown in FIG. As a result, the phase delay amount of the retarder 14 is set to λ/2 or 0.
　第１実施形態に係る偏光状態制御処理は、光量が最大となる電圧値を探索する処理を行うのに対して、第５実施形態に係る偏光状態制御処理は、光量が最小となる電圧値を探索する処理を行う。第５実施形態の処理は、この点が第１実施形態の処理と異なるだけであるため、説明を省略する。 The polarization state control process according to the first embodiment performs a process of searching for a voltage value that maximizes the light amount, whereas the polarization state control process according to the fifth embodiment determines a voltage value that minimizes the light amount. Perform the process of searching. The process of the fifth embodiment is different from the process of the first embodiment only in this point, and thus the description thereof is omitted.
　以上説明したように、第５実施形態に係る偏光状態制御装置５１０によれば、リターダ１４の出射面Ｓｏ側で反射し、再び偏光ビームスプリッタ５１２を通過して出射されたＳ偏光（Ｌ１７）の光量をモニタリングしている。偏光状態制御装置５１０は、モニタリング結果である光量に基づいて、光の光量が最小になるように、リターダ１４に印加する電圧を制御する。これにより、偏光状態制御装置５１０は、リターダ１４の位相遅れ量をλ／２又は０に設定することができる。その結果、偏光状態制御装置５１０は、図１０に示すように、回転方向が正確に左回り又は右回りの円偏光の光（Ｌ６）を、偏光グレーティング３０に入射することができる。偏光状態制御装置５１０は、偏光グレーティング３０からの出射光（Ｌ８）の回折効率を最大にすることができる。 As described above, according to the polarization state control device 510 according to the fifth embodiment, the S-polarized light (L17) that is reflected by the exit surface So side of the retarder 14 and again passes through the polarization beam splitter 512 and is output. The light intensity is monitored. The polarization state control device 510 controls the voltage applied to the retarder 14 based on the light amount that is the monitoring result so that the light amount of the light is minimized. Thereby, the polarization state control device 510 can set the phase delay amount of the retarder 14 to λ/2 or 0. As a result, the polarization state control device 510 can enter the circularly polarized light (L6) whose rotation direction is exactly left-handed or right-handed into the polarization grating 30, as shown in FIG. The polarization state control device 510 can maximize the diffraction efficiency of the emitted light (L8) from the polarization grating 30.
＜第６実施形態＞
　次に、第６実施形態について説明する。なお、第６実施形態に係る偏光状態制御装置において、第３実施形態に係る偏光状態制御装置３１０と同様の構成については、同一符号を付して詳細な説明を省略する。 <Sixth Embodiment>
Next, a sixth embodiment will be described. In the polarization state control device according to the sixth embodiment, the same components as those of the polarization state control device 310 according to the third embodiment are designated by the same reference numerals and detailed description thereof will be omitted.
　図１２に示すように、第６実施形態に係る偏光状態制御装置６１０は、第３実施形態に係る偏光状態制御装置３１０のリターダ１４と偏光グレーティング３０との主面が対向するように組み合わせられた層が、少なくとも２つ以上設けられている（複数積層されている）。図１２の例では、リターダ（第１リターダ）１４Ａと偏光グレーティング（第１偏光グレーティング）３０Ａとの組み合わせの第１層、リターダ（第２リターダ）１４Ｂと偏光グレーティング（第２偏光グレーティング）３０Ｂとの組み合わせの第２層、及びリターダ（第３リターダ）１４Ｃと偏光グレーティング（第３偏光グレーティング）３０Ｃとの組み合わせの第３層で構成される場合を例示している。また、各層におけるリターダ１４と偏光グレーティング３０とは交互に配置されるように構成されている。 As shown in FIG. 12, in the polarization state control device 610 according to the sixth embodiment, the retarder 14 and the polarization grating 30 of the polarization state control device 310 according to the third embodiment are combined so that the main surfaces thereof face each other. At least two layers are provided (a plurality of layers are stacked). In the example of FIG. 12, the first layer of the combination of the retarder (first retarder) 14A and the polarization grating (first polarization grating) 30A, the retarder (second retarder) 14B and the polarization grating (second polarization grating) 30B The case where it is configured by the second layer of the combination and the third layer of the combination of the retarder (third retarder) 14C and the polarization grating (third polarization grating) 30C is illustrated. In addition, the retarders 14 and the polarization gratings 30 in each layer are arranged alternately.
　リターダ１４Ａは第１及び第２電極２４ＡＬ，２４ＡＲが設けられ、リターダ１４Ｂは第１及び第２電極２４ＢＬ，２４ＢＲが設けられ、リターダ１４Ｃは第１及び第２電極２４ＣＬ，２４ＣＲが設けられている。リターダ１４の各々には、個別に設定された電圧値で電圧が印加される。 The retarder 14A is provided with first and second electrodes 24AL and 24AR, the retarder 14B is provided with first and second electrodes 24BL and 24BR, and the retarder 14C is provided with first and second electrodes 24CL and 24CR. A voltage is applied to each of the retarders 14 at an individually set voltage value.
　また、組み合わせの第１層、第２層、第３層の各々に対応して、ミラー１６Ａ，１６Ｂ，１６Ｃと、受光部１８Ａ，１８Ｂ，１８Ｃと、が設けられている。以下では、各層及び各層に対応する構成の各々を区別なく説明する場合には、符号のＡ，Ｂ，Ｃを省略して表記する。 Mirrors 16A, 16B and 16C and light receiving portions 18A, 18B and 18C are provided corresponding to each of the first layer, the second layer and the third layer of the combination. In the following, when the respective layers and the configurations corresponding to the respective layers are described without distinction, reference numerals A, B, and C are omitted.
　ミラー１６の各々は、対応する層の組み合わせを構成するリターダ１４の出射面Ｓｏ側であって、かつ、対応する層の組み合わせを構成する偏光グレーティング３０へ入射される前の光を反射する位置に配置される。 Each of the mirrors 16 is located on the emission surface So side of the retarder 14 forming the combination of the corresponding layers and at a position that reflects the light before being incident on the polarization grating 30 forming the combination of the corresponding layers. Will be placed.
　また、第６実施形態に係る偏光状態制御装置６１０は、第３実施形態に係る偏光状態制御装置３１０の制御部２０に代えて、制御部６２０を備える。 The polarization state control device 610 according to the sixth embodiment includes a control unit 620 instead of the control unit 20 of the polarization state control device 310 according to the third embodiment.
　図２に示す制御部２０の構成と同様に、制御部６２０は、光量取得部４２と、電圧値決定部６４４と、電圧制御部６４６と、電圧－位相遅れ量特性を記憶するＤＢ４８と、を含んで構成される。 Similar to the configuration of the control unit 20 illustrated in FIG. 2, the control unit 620 includes a light amount acquisition unit 42, a voltage value determination unit 644, a voltage control unit 646, and a DB 48 that stores a voltage-phase delay amount characteristic. It is configured to include.
　電圧値決定部６４４は、受光部１８の各々から取得された光量データに基づいて、各受光部１８に対応する層の組み合わせを構成するリターダ１４に印加する電圧値を決定する。電圧値の決定方法は、上記第１～第４実施形態に示す方法と同様である。 The voltage value determination unit 644 determines the voltage value to be applied to the retarder 14 that constitutes the combination of layers corresponding to each light receiving unit 18, based on the light amount data acquired from each of the light receiving units 18. The method of determining the voltage value is the same as the method shown in the first to fourth embodiments.
　電圧制御部６４６は、電圧値決定部６４４により決定された各層に対応する電圧値が、第１及び第２電極２４Ｌ，２４Ｒを介して、対応する層の組み合わせを構成するリターダ１４に印加されるように、制御用電源２２に設定する。 The voltage control unit 646 applies the voltage value corresponding to each layer determined by the voltage value determination unit 644 to the retarder 14 that forms a combination of corresponding layers via the first and second electrodes 24L and 24R. As described above, the power source for control 22 is set.
　以上説明したように、第６実施形態に係る偏光状態制御装置６１０によれば、リターダ１４と偏光グレーティング３０とが組み合わせられた層が、２つ以上設けられている。偏光状態制御装置６１０は、各層のリターダ１４の位相遅れ量を、それぞれ独立してλ／２又は０に設定する。これにより、偏光状態制御装置６１０は、複数の偏光グレーティング３０により、単一光源を用いて複数の方向へ出射光を回折させることができる。 As described above, according to the polarization state control device 610 according to the sixth embodiment, two or more layers in which the retarder 14 and the polarization grating 30 are combined are provided. The polarization state control device 610 independently sets the phase delay amount of the retarder 14 of each layer to λ/2 or 0. Thereby, the polarization state control device 610 can diffract the emitted light in a plurality of directions by using the single light source by the plurality of polarization gratings 30.
　なお、上記各実施形態において参照する電圧－位相遅れ量特性は、図１３に示すように、温度変化によって関数曲線が変化する。そこで、上記各実施形態に係る偏光状態制御装置は、異なる複数の温度毎に、電圧－位相遅れ量特性を予め記憶しておき、周囲温度をモニタリングし、周囲温度に対応する電圧－位相遅れ量特性を選択して、上記各実施形態のように電圧値を決定してもよい。これにより、上記各実施形態に係る偏光状態制御装置は、リターダ１４の個体差や経年劣化等に起因する位相遅れ量のずれだけでなく、使用時の温度変化に起因する位相遅れ量のずれも解消して、常時位相遅れ量を最適化することができる。 In the voltage-phase delay amount characteristic referred to in each of the above-described embodiments, as shown in FIG. 13, the function curve changes with temperature change. Therefore, the polarization state control device according to each of the above embodiments stores the voltage-phase delay amount characteristic in advance for each of a plurality of different temperatures, monitors the ambient temperature, and measures the voltage-phase delay amount corresponding to the ambient temperature. You may select a characteristic and determine a voltage value like each above-mentioned embodiment. As a result, the polarization state control device according to each of the above-described embodiments not only shifts the phase delay amount due to the individual difference of the retarder 14 or deterioration over time, but also shifts the phase delay amount due to the temperature change during use. Therefore, the amount of phase delay can be optimized at all times.
　また、上記各実施形態をそれぞれ組み合わせて実施することもできる。例えば、第４実施形態及び第５実施形態の構成において、リターダ１４と偏光グレーティング３０との組合せを多層にする構成としてもよい。 Also, the above embodiments can be combined and implemented. For example, in the configurations of the fourth and fifth embodiments, the combination of the retarder 14 and the polarization grating 30 may be a multilayer configuration.
　また、上記各実施形態に係る偏光状態制御処理を実行するための偏光状態制御プログラムは、コンピュータが読み取り可能な記録媒体に記録し提供してもよい。 The polarization state control program for executing the polarization state control processing according to each of the above embodiments may be recorded in a computer-readable recording medium and provided.
　上記各実施形態のように、所望の偏光状態の出射光を得られる構成は、レーザレーダ等の光ビームスキャナ、レーザ加工機などに用いることができる。 The configuration capable of obtaining emitted light in a desired polarization state as in each of the above-described embodiments can be used in a light beam scanner such as a laser radar, a laser processing machine, or the like.

Claims (10)

  1. 　光源光を直線偏光に偏光する直線偏光子と、
    　前記直線偏光子を通過した光源光が入射されると共に、印加される電圧に応じて、入射された光の偏光状態を変えて出射するリターダと、
    　前記直線偏光子を通過した光源光の一部を、前記リターダの出射面側において入射面側に反射させる反射板と、
    　前記反射板により反射されて、前記直線偏光子を通過した光を受光する受光部と、
    　前記受光部により受光された光の光量に基づいて、前記入射された光をλ／２又は０の位相遅れで偏光した光が前記リターダから出射されるように、前記リターダに印加する電圧を制御する制御部と、
    　を含む、偏光状態制御装置。     A linear polarizer that polarizes the source light into linearly polarized light,
    The light source light that has passed through the linear polarizer is incident, and according to the applied voltage, a retarder that changes the polarization state of the incident light and emits light,
    A part of the light source light that has passed through the linear polarizer, a reflection plate that reflects to the incident surface side on the exit surface side of the retarder,
    A light receiving section that receives the light that has been reflected by the reflecting plate and that has passed through the linear polarizer,
    The voltage applied to the retarder is controlled so that light obtained by polarizing the incident light with a phase delay of λ/2 or 0 is emitted from the retarder based on the amount of light received by the light receiving unit. Control unit to
    A polarization state control device including:
  2. 　光が前記反射板で反射されない光路上であって、前記直線偏光子と前記リターダとの間に配置される１／４波長板をさらに含む、
    　請求項１に記載の偏光状態制御装置。     Further comprising a quarter-wave plate disposed on the optical path where light is not reflected by the reflector and between the linear polarizer and the retarder.
    The polarization state control device according to claim 1.
  3. 　光が前記反射板で反射される光路上であって、前記直線偏光子と前記リターダとの間に配置される１／４波長板をさらに含む、
    　請求項１又は請求項２に記載の偏光状態制御装置。     A quarter-wave plate disposed on the optical path of light reflected by the reflection plate and between the linear polarizer and the retarder,
    The polarization state control device according to claim 1 or 2.
  4. 　前記リターダから出射された光が入射される偏光グレーティングをさらに含み、
    　前記反射板は、前記偏光グレーティングへ入射される前の光を反射する、
    　請求項２又は請求項３に記載の偏光状態制御装置。     Further comprising a polarization grating on which the light emitted from the retarder is incident,
    The reflection plate reflects the light before entering the polarizing grating,
    The polarization state control device according to claim 2 or 3.
  5. 　前記リターダと前記偏光グレーティングとの組み合わせが複数積層され、
    　前記反射板及び前記受光部は、前記組み合わせの各々に対応して設けられ、
    　前記制御部は、前記受光部の各々により受光された光の光量に基づいて、前記受光部に対応する前記組み合わせを構成する前記リターダに印加する電圧を制御する、
    　請求項４に記載の偏光状態制御装置。     A plurality of combinations of the retarder and the polarization grating are laminated,
    The reflector and the light receiving unit are provided corresponding to each of the combinations,
    The control unit controls a voltage applied to the retarder forming the combination corresponding to the light receiving unit, based on the amount of light received by each of the light receiving units,
    The polarization state control device according to claim 4.
  6. 　前記制御部は、前記受光部により受光された光の光量が最大となるように、前記リターダに印加する電圧を制御する、
    　請求項１～請求項５のいずれか１項に記載の偏光状態制御装置。     The control unit controls the voltage applied to the retarder so that the amount of light received by the light receiving unit is maximized,
    The polarization state control device according to any one of claims 1 to 5.
  7. 　前記直線偏光子は、入射方向へＰ偏光の光を出射し、前記入射方向と直交する方向へＳ偏光の光を出射する偏光ビームスプリッタであり、
    　前記受光部は、前記偏光ビームスプリッタから出射されるＳ偏光の光を受光し、
    　前記制御部は、前記受光部で受光されたＳ偏光の光の光量が最小となるように、前記リターダに印加する電圧を制御する、
    　請求項１～請求項５のいずれか１項に記載の偏光状態制御装置。     The linear polarizer is a polarization beam splitter that emits P-polarized light in an incident direction and emits S-polarized light in a direction orthogonal to the incident direction.
    The light receiving unit receives the S-polarized light emitted from the polarization beam splitter,
    The control unit controls the voltage applied to the retarder so that the amount of S-polarized light received by the light receiving unit is minimized.
    The polarization state control device according to any one of claims 1 to 5.
  8. 　前記制御部は、予め設定された、前記リターダに印加する電圧に対する位相遅れ量の特性において、所定の電圧値より低い電圧値の第１数値範囲において、位相遅れ量がλ／２となる電圧値を探索し、前記所定の電圧値より高い電圧値の第２数値範囲において、位相遅れ量が０となる電圧値を探索する、
    　請求項１～請求項７のいずれか１項に記載の偏光状態制御装置。     In the preset characteristic of the phase delay amount with respect to the voltage applied to the retarder, the control unit sets a voltage value at which the phase delay amount is λ/2 in the first numerical range of the voltage value lower than the predetermined voltage value. Is searched for in the second numerical value range of the voltage value higher than the predetermined voltage value, and the voltage value at which the phase delay amount becomes 0 is searched.
    The polarization state control device according to any one of claims 1 to 7.
  9. 　前記制御部は、予め設定された、前記リターダに印加する電圧に対する位相遅れ量の特性において、λ／２又は０の位相遅れ量に対応する電圧値の近傍で、前記リターダに印加する電圧値を探索する、
    　請求項１～請求項８のいずれか１項に記載の偏光状態制御装置。     In the characteristic of the phase delay amount with respect to the voltage applied to the retarder set in advance, the control unit controls the voltage value applied to the retarder in the vicinity of the voltage value corresponding to the phase delay amount of λ/2 or 0. Explore,
    The polarization state control device according to any one of claims 1 to 8.
  10. 　コンピュータを、請求項１～請求項９のいずれか１項に記載の偏光状態制御装置として機能させるための偏光状態制御プログラムが記録された記録媒体。 A recording medium recording a polarization state control program for causing a computer to function as the polarization state control device according to any one of claims 1 to 9.
PCT/JP2020/004144 2019-02-05 2020-02-04 Polarization state control device and computer-readable recording medium WO2020162458A1 (en)

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