CN108388055A - A kind of liquid crystal tunable filter based on Lyot-Solc composite constructions - Google Patents
A kind of liquid crystal tunable filter based on Lyot-Solc composite constructions Download PDFInfo
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- CN108388055A CN108388055A CN201810177301.XA CN201810177301A CN108388055A CN 108388055 A CN108388055 A CN 108388055A CN 201810177301 A CN201810177301 A CN 201810177301A CN 108388055 A CN108388055 A CN 108388055A
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- liquid crystal
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- 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
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1347—Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
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- Nonlinear Science (AREA)
- Mathematical Physics (AREA)
- Chemical & Material Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
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- Optics & Photonics (AREA)
- Liquid Crystal (AREA)
Abstract
A kind of liquid crystal tunable filter based on Solc Lyot composite constructions is a kind of automatically controlled tunable optically filtering device.The present invention realizes the automatically controlled tuning of transmission spectrum by changing driving voltage, can be used for Photoelectric Detection, the fields such as light spectrum image-forming.The compound liquid crystal tunable filter (liquid crystal tunable filter LCTF) includes mainly the composite construction being made of Solc and Lyot, and the power drive system being made of signal generator and voltage amplifier.The compound LCTF transmitted spectrums combine Lyot type structures narrow halfwidth and Solc type structures high-transmission rate the characteristics of, by rational structure design, improve spectral-transmission favtor, while having effectively removed in visible spectrum and secondary to have penetrated peak.
Description
Technical field
Liquid crystal tunable filter of the present invention is a kind of new structural liquid crystal tunable filter, is based on
The composite construction of Solc and Lyot, by rational structure design and material selection, realizing high efficiency, narrowband wave transparent and electricity can
Tuning.
Background technology
One has efficient Tunable Birefringent Filters in optic communication, light spectrum image-forming, remote sensing and field of display
There are many important applications.
In EO-1 hyperion field, with the continuous renewal of sensor, people can be flat in different Aeronautics and Astronautics remote sensing
The remote sensing image of spatial resolution and spectral resolution when obtaining different on platform.High-spectrum remote-sensing compared with previous remote sensing technology,
Feature with collection of illustrative plates and from visible light to a series of infrared or even thermal infrared wave bands, is a kind of comprehensive remote sensing skill
Art means.In the application of high-spectrum remote-sensing, optical filter used at present is proposed with multiple peak narrowband and tunable
The requirement of characteristic.In light spectrum image-forming field, since liquid crystal tunable filter (LCTF) also has in wider spectral region
Very high transmissivity and it can realize that the selection to specific wavelength penetrates by the adjusting of electrically-controlled liquid crystal birefringence, so it
It is on a good wicket for manufacturing in EO-1 hyperion polarization imaging remote sensing equipment element.
LCTF, that is, liquid crystal tunable filter (Liquid crystal tunable filter) is filtered with some typical opticals
Wave device is such as following compared to having the advantages that：
(1) small, light-weight, do not have moving component；
(2) spectral resolution is high, Free Spectral Range (FSR) is wide；
(3) driving voltage is relatively low, clear aperature is big, low in energy consumption；
Although LCTF has the advantages that so more, current most of LCTF use cascade connection type Lyot structures, are deposited in this structure
In multi-disc polarization optical element so that filter is always larger through light intensity loss, especially when spectral resolution is higher, LCTF's
Level increases therewith, and the transmitance loss and response time thus brought with the increase of advanced secondary liquid crystal plate thickness, which reduces, is
Inevitably.Therefore, there is an urgent need for a kind of structural design schemes improving LCTF efficiency.
Solc type LCTF structures only have two pieces of polarizing films, and N grades of Lyot type LCTF structures have (N+1) block polarizing film, because
The transmitance loss of this Solc type structure is less, but its transmitted spectrum resolution ratio is relatively low compared to Lyot structures, with series at line
Sex ratio relationship, and the resolution ratio of Lyot types and series are at geometric progression variation relation.Therefore, the present invention proposes that one kind is based on
The composite construction of Solc-Lyot, combine Lyot type structures narrow halfwidth and Solc type structures high-transmission rate the characteristics of, lead to
Rational structure design is crossed, spectral-transmission favtor is improved, while having been effectively removed secondary through peak in visible spectrum
Invention content
The wanted technology of the present invention solves the problems, such as：A kind of liquid crystal tunable filter design scheme is provided, realizes optics filter
The narrowband of wave device, tunable and fast response characteristic.
Technical solution of the invention is：A kind of liquid crystal tunable filter based on Lyot-Solc composite constructions,
Including：The 3 grades of expansion Solc structures and 2 grades of Lyot structures that are made of polarizing film, multistage LCD panel and by signal generator
With the power drive system of voltage amplifier composition.
Solc type structures：The structure of Solc type liquid crystal tunable filters is divided into collapsible (folded) and expansion
(fan), expansion structure is as shown in Figure 1, the polarizer and analyzer keeping parallelism, liquid crystal plate thickness is equal, and divides with its liquid crystal
Sub- director is with the saturating folk prescription of the polarizer to angled α, 3 α ... (2i-1) α, and (α=45 °/N), N is the series of model, that is, liquid
The number of chip.
Lyot type structures：The structure of Lyot type liquid crystal tunable filters is as shown in Fig. 2, be the polarizer, quartz-crystal successively
Body phase delay chip, liquid crystal tunable phase delay device, analyzer.The polarizer is parallel along light transmission shaft with analyzer, quartz plate
The light transmission shaft angle at 45 ° of the differently- oriented directivity and the polarizer of optical axis direction and liquid crystal cell.
Passing through the polarizer when incident non-polarized becomes linearly polarized light, and phase delay is generated using quartz plate and liquid crystal board,
Its polarization state can change again, and the ratio of light intensity and incident intensity that specific wavelength is measured after analyzer is worth to its transmission
Rate.
Individual Lyot mode filter multiresolutions are preferable, but transmitance is low, inhibit poor in addition；Individual Solc types filter
Wave device transmissivity is high, but secondary lobe is few, and band outward leakage is high, thus the present invention is filtered using two kinds of structures in the same liquid crystal tunable
In device, the advantages of both preferably combining.
The structure of 3 grades of Solc-2 grades of Lyot type liquid crystal tunable filters of the present invention is as shown in figure 3, from left to right successively
It is 3 expansion grade Solc structures and 2 grades of Lyot type structures, wherein Solc structures select 5 μ m-thick liquid crystal cell of three pieces, the choosing of Lyot structures
Use 0.4mm thickness quartz plate and 5 μ m-thick liquid crystal cells as first order phase retardation plate, 0.8mm thickness quartz plate and 10 μ m-thick liquid crystal cells
As second level phase retardation plate.The electrically conerolled birefringence of 5 μ m-thick nematic liquid crystal E7 is as shown in Figure 4.
The transmitted spectrum of 3 grades of Solc-2 grades of Lyot type liquid crystal tunable filters of the present invention is as shown in Figure 5-Figure 7.2 grades
Lyot structure transmission spectrums are 13nm- in half high bandwidth of filtering of 400nm to 650nm spectral coverage ranges in narrowband, multimodal characteristic
22nm.The transmission spectrum of 3 grades of Solc structures is in broadband, but the apparent characteristic of Sidelobe Suppression.Composite construction is by Solc structures and Lyot
The spectral transmission peak of structure matches, and finally realizes unimodal, narrowband emergent light.Utilize the electrically conerolled birefringence of nematic liquid crystal E7
Characteristic, it is 1.61V to load amplitude respectively to the liquid crystal board of Solc structures, when the drive signal of 1.45V, 1.25V, obtains output light
The centre wavelength of spectrum is respectively 433nm, 510nm, 595nm, corresponding halfwidth 13nm, 16nm, 22nm.
Description of the drawings
Fig. 1 is the expansion Solc type structures of the present invention；
Fig. 2 is the Lyot type structures of the present invention；
Fig. 3 is the composite structured of the present invention；
Fig. 4 is the nematic liquid crystal electrically conerolled birefringence of the present invention；
Fig. 5 is the compound LCTF spectral-transmission favtors curves of Solc-Lyot of the present invention, centre wavelength 443nm；
Fig. 6 is the compound LCTF spectral-transmission favtors curves of Solc-Lyot of the present invention, centre wavelength 510nm；
Fig. 7 is the compound LCTF spectral-transmission favtors curves of Solc-Lyot of the present invention, centre wavelength 595nm；
Specific implementation mode
It will be described in detail the principle and the simulation experiment result of liquid crystal tunable filter herein.
For Lyot structures：
Incident light is non-polarized light, then set the Jones vector of incident light asIf polarizer light transmission shaft is x
Axis, then the Jones matrix of single-stage Lyot models is：
M=PR (45 °) G (Γ) R (- 45 °) R (45 °) G (ΓP)R(-45°)P
Transmissivity is obtained using Jones matrix：
Wherein spin matrixPhase delay device matrix
Transmission optical axis is the linear polarizer of x-axisPassive phase delay shifter phase delay ΓP=(2 π Δs n2d2/ λ), d2
For passive phase delay shifter thickness, Δ n2For the birefringence of passive phase delay shifter.The phase delay Γ of liquid crystal=(2 π Δs
n1d1/ λ), d1For the thickness of liquid crystal, Δ n1For the effective birefringence rate of liquid crystal.
For Solc structures：
Accordion structure then folds (folded) formula Solc mode filter models for N grades if polarizer light transmission shaft is x-axis
Jones matrix M：
M=P1…R(α)G(Γ)R(-α)R(-α)G(Γ)R(α)R(α)G(Γ)R(-α)R(-α)G(Γ)R(α)P
Transmissivity T：
Wherein light transmission shaft is the linear polarizer of y-axisLight transmission shaft is the linear polarizer of x-axis
Other parameters are with reference to Lyot type structures.
Expansion structure, wherein the light transmission shaft of follow-up each piece of LCD panel molecular long axis and the polarizer is successively at α, 3 α ...
(2i-1) α, (α=45 °/N).If polarizer light transmission shaft is x-axis, then Jones of N grades of expansion (fan) Solc mode filter models
Matrix M：
M=PR ((2N-1) α) G (Γ) R (- (2N-1) α) ... R (3 α) G (Γ) R (- 3 α) R (α) G (Γ) R (- α) P
Transmissivity T：
Other relevant parameters are the same as (folded) formula of folding.
Expansion structure with it is collapsible similar, the polarizer and analyzer keeping parallelism relationship, each piece follow-up at this time
The light transmission shaft of LCD panel molecular long axis and the polarizer is successively at α, 3 α ... (2i-1) α, (α=45 °/N).If polarizer light transmission shaft is
X-axis, then the Jones matrix M of N grades of expansion (fan) Solc mode filter models：
M=PR ((2N-1) α) G (Γ) R (- (2N-1) α) ... R (3 α) G (Γ) R (- 3 α) R (α) G (Γ) R (- α) P
Transmissivity T：
Other relevant parameters are the same as (folded) formula of folding.
Since Lyot types filter plate generally several transmission peaks can all occur in the range of visible spectrum, consider
Solc types filter plate can be as the property of a bandpass filter, it is possible to by the two complementary structure, be filtered using Solc
Piece filters to obtain specific band, and it is compound to construct a Solc-Lyot in limit of visible spectrum only there are one transmission peaks
Filter.The structure of the Solc-Lyot type liquid crystal tunable filters of the present invention is as shown in figure 3, be from left to right 3 grades of exhibitions successively
Open form Solc structures and 2 grades of Lyot structures.Wherein, in Lyot types structure the first level quartz crystal thickness d2=0.4mm, liquid
Liquid crystal thickness d=5 μ nm in crystal layer thickness d=5 μ nm, Solc type structures.
It is the emulation transmittance graph of 3 grades of Solc-2 grades of Lyot types LCTF as shown in Figure 5, there was only one in visible spectrum
A peak value is in the transmission peaks main peak of 433nm, and logical halfwidth (FWHM) is approximately 13nm.Change liquid crystal board in Solc structures to drive
Signal amplitude makes its transmission peaks match with transmission peaks at the 510nm of Lyot structures, as shown in fig. 6, its in visible spectrum only
There are one peak values in the transmission peaks main peak of 510nm, and halfwidth (FWHM) is approximately 16nm.Change liquid crystal board in Solc structures to drive
Dynamic signal amplitude, makes its transmission peaks match with transmission peaks at the 595nm of Lyot structures, as shown in fig. 7, it is in visible spectrum
Only there are one peak values in the transmission peaks main peak of 595nm, and halfwidth (FWHM) is approximately 22nm.
As can be seen that 3 grades of solc-2 grades of Lyot type composite construction liquid crystal tunable filters combine Lyot types structure and
The advantages of Solc type structures, present invention greatly enhances spectral resolutions, and reduce with the serious problem of outward leakage.This
Outside, Lyot structures other main peaks in visible spectrum have also been filtered out, a unique main peak has been left behind, has solved multi-peak
Interference problem.
The content that description in the present invention is not described in detail belongs to the prior art well known to professional and technical personnel in the field.
Claims (6)
1. a kind of liquid crystal tunable filter based on Solc-Lyot composite constructions, which is characterized in that the LCTF filters use
On the one hand Solc-Lyot composite constructions by the material selection of rational structure design and optimization reduce Solc structures peak
Be worth halfwidth it is larger, with the larger phenomenon of outward leakage, on the one hand solve Lyot structures possess in visible light wave range it is multiple
The problem of penetrating peak.
2. 1. composite structured LCTF as described in claim 1 is from left to right followed successively by (1) polarizing film, (2) liquid crystal board 1.,
(3) liquid crystal board 2., (4) liquid crystal board 3., (5) polarizing film 2., (6) liquid crystal board 4., (7) quartz plate 1., (8) polarizing film 3., (9) liquid
Brilliant plate 5., (10) quartz plate 2., (11) polarizing film 4., wherein before three pieces liquid crystal boards constitute 3 grades of deploying type Solc structures, after
Two panels liquid crystal board constitutes 2 grades of Lyot structures.
3. deploying type Solc structure features as described in claim 1 are that liquid crystal plate thickness is equal, the polarizer is protected with analyzer
Maintain an equal level row, and the liquid crystal board differently- oriented directivity of i-stage and the light transmission shaft angle of the polarizer are (2i-1) α, (α=45 °/N).
4. every grade of Lyot structures as described in claim 1 are from left to right the polarizer successively, liquid crystal phase-plate, quartz plate, analyzing
The thickness of device, rear stage time liquid crystal board and quartz plate is respectively two times of preceding level.The polarizer is mutually flat with analyzer light transmission shaft
Row, the differently- oriented directivity of liquid crystal board and the light transmission shaft of polarizer angle at 45 °.
5. as described in claim 1, passing through the polarizer when incident non-polarized becomes linearly polarized light, then is generated by electrically-controlled liquid crystal plate
Phase delay, polarization state change correspondingly, and polarization state change is related to wavelength, then filter to obtain corresponding wave band by analyzer.Pass through
The electric field of additional varying strength will make the light transmission of different wave length that height occur and change, and then realize and select different waves
Long light passes through, and achievees the purpose that filtering.
6. liquid crystal board as described in claim 1, which is characterized in that use Nematic phase liquid crystal material, realized by extra electric field
Continuously adjustable electrically conerolled birefringence, specially：
(1) liquid crystal board is covered with the glass substrate opposite direction of indium oxide tin film by two panels and is composed, and substrate spacing is small by polystyrene
Ball is controlled as spacer, is assembled into a liquid crystal cell.It is coated with liquid crystal aligning layer on glass substrate, utilizes light control orientation material
It realizes parallel-oriented, is fed into liquid crystal cell using siphonic effect, liquid crystal molecule director is made to be parallel to differently- oriented directivity arrangement.
(2) when the ITO conductive layer of glass baseplate surface loads electric signal, when a threshold is exceeded, electroluminescent pole occurs for liquid crystal molecule
Change, interacts with electric field strength, lead to liquid crystal molecule director run-off the straight, in a certain angle with substrate, this angle depends on
It is unrelated with electric field strength direction in electric field strength size.The change of liquid crystal molecule director alignment causes liquid crystal layer refractive index to be sent out
Changing, to realize the automatically controlled phase retardation modulation to incident light.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810177301.XA CN108388055A (en) | 2018-03-02 | 2018-03-02 | A kind of liquid crystal tunable filter based on Lyot-Solc composite constructions |
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| CN201810177301.XA CN108388055A (en) | 2018-03-02 | 2018-03-02 | A kind of liquid crystal tunable filter based on Lyot-Solc composite constructions |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115390293A (en) * | 2022-10-31 | 2022-11-25 | 长春理工大学 | Multi-passband liquid crystal tunable filtering method applied to laser communication |
| CN116862819A (en) * | 2023-05-29 | 2023-10-10 | 武汉工程大学 | Near infrared hyperspectral imaging method and system based on liquid crystal tunable filter |
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| CN115390293A (en) * | 2022-10-31 | 2022-11-25 | 长春理工大学 | Multi-passband liquid crystal tunable filtering method applied to laser communication |
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