CN109781262A - A kind of calibration bearing calibration of liquid crystal tunable filter central wavelength and device - Google Patents
A kind of calibration bearing calibration of liquid crystal tunable filter central wavelength and device Download PDFInfo
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Abstract
The present invention relates to wave filter technology fields, disclose a kind of calibration bearing calibration of liquid crystal tunable filter central wavelength and device, the function changed with the function and liquid crystal phase retardation amount of wavelength change with driving voltage by demarcating phase-delay quantity, the driving voltage of liquid crystal tunable filter polarization interference units at different levels is generated using simulation calculation based on drive factor, and correction coefficient is calculated to survey central wavelength and set the deviation of central wavelength, automatically correct driving voltage corresponding to liquid crystal tunable filter central wavelength, improve the accuracy rate and efficiency of the calibration of liquid crystal tunable filter central wavelength.
Description
Technical field
The present invention relates to wave filter technology field more particularly to a kind of calibration corrections of liquid crystal tunable filter central wavelength
Method and device.
Background technique
Liquid crystal tunable filter is a kind of programmable narrow band optical filter part, can will be seen that light/near-infrared is continuous
Spectral resolution is at nearly 1000 independent wave bands, high light spectrum image-forming made of liquid crystal tunable filter is combined with imaging sensor
System can obtain the high-resolution spatial information and spectral information of detection target by way of wave band Time share scanning.Based on liquid crystal
The Hyperspectral imager of tunable optic filter makes us obtain tremendous increase to target identification ability, in camouflage identification, forges
Identification, terrain classification, environmental monitoring and assessment, resources remote sensing investigation, medical diagnosis etc. need to identify the careful optical strength of target,
The field of polarization state and spectrum signature will play a significant role.
Liquid crystal tunable filter generallys use multiple liquid crystal polarized interference unit cascades to realize optically filtering, i.e., only permits
Perhaps the light of the narrow-band spectrum centered on a certain wavelength is by ending the light of other wavelength, therefore, liquid crystal tunable filter
Need liquid crystal polarized interference units at different levels that there is maximum transmitance in specified central wavelength when work, meanwhile, in middle cardiac wave
The long outer at least liquid crystal polarized interference unit of level-one has wavelength cut-off ability.The calibration of liquid crystal tunable filter is found most
Excellent liquid crystal polarized interference units at different levels designated centers wavelength have maximum transmission driving voltage, make cascading at
Liquid crystal tunable filter has favorable optical performance.
Since the equivalent phase retardation of the polarization interference units at different levels of liquid crystal tunable filter is different, polarizations at different levels are dry
Unit transmission spectrum curve is related to be generally difficult to meet maximum transmission condition simultaneously in the wavelength of setting, meanwhile, liquid crystal tunable
The polarization interference unit transmission spectrum curves at different levels of filter have multiple maximum and minimum.Therefore, how from every level-one
One is selected in many maximum of polarization interference unit and is driven to the central wavelength position of setting, is liquid crystal tunable filtering
Device calibration critical issue, to the wavelength accuracy of liquid crystal tunable filter, transmitance, bandwidth (FWHM) and with it is outer cut-off etc.
The superiority and inferiority of critical performance parameters plays a decisive role.
In liquid crystal tunable filter central wavelength calibration process, since the transmitted light of polarization interference units at different levels is set a song to music
Line has multiple maximum, while there is also the numerous poles that generation is related to because of liquid crystal phase retardation device Fabry-glass Luo Gan
Therefore big minimum would generally generate large error with computer come automatic interpretation peak center wavelength, at present liquid crystal tunable
The calibration of filter center wavelength is based on manually demarcating.A central wavelength is specified first, adjusts driving voltage, and driving is every
Then the corresponding wavelength of a peak value of level-one polarization interference unit transmitted spectrum specifies cardiac wave in another to the designated value again
It is long, driving voltage is adjusted, drives the corresponding wavelength of a peak value of every level-one polarization interference unit transmitted spectrum to the designated value,
It circuits sequentially, completes to designated centers Wavelength calibration in liquid crystal tunable filter working range.The wavelength of this scaling method
Accuracy depends on artificial interpretation, and the raising of the tuning resolution ratio with liquid crystal tunable filter, such as 0.1nm is needed to tune
When resolution ratio, the accuracy of artificial interpretation is then difficult to ensure, meanwhile, the central wavelength number of calibration reaches 103-104, demarcates work
It increased dramatically as amount.
In addition, selecting different transmitted spectrum maximum to every level-one polarization interference unit, then liquid crystal after cascade is corresponded to
Tunable optic filter has different bandwidth (FWHM), with outer cut-off and transmitance etc..With liquid crystal tunable filter
The raising of spectral resolution, the polarization interference unit series needed increase, and every increase level-one bring maximum combined number is then
Increased in a manner of the order of magnitude, in the maximum combination of the polarization interference units at different levels of huge number, artificial calibration is only capable of taking out
Take a few combination, the liquid crystal tunable filter bandwidth (FWHM) of cascading, with the parameters such as outer cut-off and transmitance
It is difficult to meet the requirements, currently, the calibration of central wavelength becomes the more high-resolution liquid crystal tunable filter research of cascade series
One key restriction factors of exploitation.
Due to the variation of liquid crystal phase retardation piece manufacturing process or environment temperature in liquid crystal polarized interference unit, liquid crystal is inclined
The corresponding wavelength of vibration interference unit transmitted spectrum maximum can also change, and current scaling method, which does not have still, becomes wavelength
Change corrected ability, therefore, each liquid crystal tunable filter will carry out independent calibration.
Summary of the invention
It is a primary object of the present invention to propose that a kind of liquid crystal tunable filter central wavelength demarcates bearing calibration and dress
It sets, improves the accuracy rate and efficiency of the calibration of liquid crystal tunable filter central wavelength.
To achieve the above object, a kind of liquid crystal tunable filter central wavelength provided by the invention demarcates bearing calibration,
Include:
It is obtained with wavelength change function and liquid crystal phase retardation amount with driving voltage variation function calculating according to phase-delay quantity
Obtain drive factor；
Central wavelength is set for the liquid crystal polarized interference units at different levels in liquid crystal tunable filter, according to preset center
The corresponding drive factor of wavelength calculates the driving voltage of the liquid crystal polarized interference unit at different levels；
The actual measurement central wavelength under the driving voltage is obtained, the actual measurement central wavelength and the preset center are calculated
Deviation between wavelength；
Judge whether the deviation is less than deviation threshold, if so, filtering the driving voltage as liquid crystal tunable
The driving voltage of the central wavelength of wave device；
Otherwise, correction coefficient is calculated according to the actual measurement central wavelength and the preset central wavelength；
The driving voltage is updated according to the correction coefficient, until the deviation is less than the deviation threshold.
Optionally, described to be changed with wavelength change function and liquid crystal phase retardation amount with driving voltage according to phase-delay quantity
Function calculates acquisition drive factor
Phase-delay quantity is obtained with wavelength change function, the phase-delay quantity includes liquid crystal phase with wavelength change function
Retardation is with wavelength change function and stationary phase retardation with wavelength change function；
It obtains liquid crystal phase retardation amount and changes function with driving voltage；
Change letter with driving voltage with wavelength change function and the liquid crystal phase retardation amount according to the phase-delay quantity
Number, which calculates, obtains drive factor.
Optionally, the actual measurement central wavelength obtained under the driving voltage, calculates the actual measurement central wavelength and institute
The deviation stated between preset central wavelength includes:
The driving voltage is generated to drive liquid crystal polarized interference units at different levels using liquid crystal driver, is examined by spectrometer
The corresponding central wavelength of maximum for surveying transmission spectrum curve is actual measurement central wavelength, calculate the actual measurement central wavelength with it is described
Deviation between preset central wavelength.
Optionally, described that the driving voltage is updated according to the correction coefficient, until the deviation is inclined less than described
Poor threshold value includes:
By the corresponding drive factor of the preset central wavelength multiplied by the correction coefficient, updated driving system is obtained
Number；
Updated driving voltage is calculated according to the updated drive factor；
Obtain the actual measurement central wavelength under the updated driving voltage, calculate the actual measurement central wavelength with it is described pre-
If central wavelength between deviation；
Back to judging whether the deviation is less than deviation threshold step, until the deviation is less than the deviation threshold
Value.
Optionally, the liquid crystal phase retardation amount is with wavelength change function representation are as follows: Δ ndLC(λ)；
The stationary phase retardation is with wavelength change function representation are as follows: Δ ndQ(λ)；
The corresponding drive factor of the liquid crystal polarized interference unit at different levels indicates are as follows:
......
The correction coefficient is expressed as:
Wherein, λ is wavelength；For transmission spectrum curve maximum, k is natural number；δiFor liquid crystal at different levels
The stationary phase of polarization interference unit postpones；T is filter function.
As another aspect of the present invention, a kind of liquid crystal tunable filter central wavelength calibration means for correcting provided,
Include:
Drive factor obtains module, is used for according to phase-delay quantity with wavelength change function and liquid crystal phase retardation amount with drive
Dynamic voltage change function, which calculates, obtains drive factor；
Driving voltage computing module, for in the liquid crystal polarized interference unit settings at different levels in liquid crystal tunable filter
Cardiac wave is long, and the driving electricity of the liquid crystal polarized interference unit at different levels is calculated according to the corresponding drive factor of preset central wavelength
Pressure；
Demarcating module, for obtaining the actual measurement central wavelength under the driving voltage, calculate the actual measurement central wavelength and
Deviation between the preset central wavelength；
Judgment module, for judging whether the deviation is less than deviation threshold, if so, using the driving voltage as
The driving voltage of the central wavelength of liquid crystal tunable filter；
Correction coefficient computing module is used for when the deviation is not less than deviation threshold, according to cardiac wave in the actual measurement
It is long to calculate correction coefficient with the preset central wavelength；
Correction module, for updating the driving voltage according to the correction coefficient, until the deviation is less than described
Deviation threshold.
Optionally, the drive factor acquisition module includes:
First function acquiring unit, for obtaining phase-delay quantity with wavelength change function, the phase-delay quantity is with wave
Long variation function include liquid crystal phase retardation amount with wavelength change function and stationary phase retardation with wavelength change function；
Second function acquiring unit changes function with driving voltage for obtaining liquid crystal phase retardation amount；
Drive factor acquiring unit, for being prolonged according to the phase-delay quantity with wavelength change function and the liquid crystal phase
Amount calculates with driving voltage variation function and obtains drive factor late.
Optionally, the demarcating module includes:
The driving voltage is generated to drive liquid crystal polarized interference units at different levels using liquid crystal driver, is examined by spectrometer
The corresponding central wavelength of maximum for surveying transmission spectrum curve is actual measurement central wavelength, calculate the actual measurement central wavelength with it is described
Deviation between preset central wavelength.
Optionally, the correction module includes:
Drive factor updating unit, for being multiplied by the correction by the corresponding drive factor of the preset central wavelength
Number, obtains updated drive factor；
Driving voltage updating unit, for updated driving electricity to be calculated according to the updated drive factor
Pressure；
Deviation updating unit, for obtaining the actual measurement central wavelength under the updated driving voltage, described in calculating
Survey the deviation between central wavelength and the preset central wavelength；
Cycling element judges whether the deviation is less than deviation threshold step for returning to, until the deviation
Less than the deviation threshold.
Optionally, the liquid crystal phase retardation amount is with wavelength change function representation are as follows: Δ ndLC(λ)；
The stationary phase retardation is with wavelength change function representation are as follows: Δ ndQ(λ)；
The corresponding drive factor of the liquid crystal polarized interference unit at different levels indicates are as follows:
......
The correction coefficient is expressed as:
Wherein, λ is wavelength；For transmission spectrum curve maximum, k is natural number；δiFor liquid crystal at different levels
The stationary phase of polarization interference unit postpones；T is filter function.
A kind of liquid crystal tunable filter central wavelength calibration bearing calibration proposed by the present invention and device, this method packet
It includes: being driven with wavelength change function and liquid crystal phase retardation amount with driving voltage variation function calculating according to phase-delay quantity
Coefficient；Central wavelength is set for the liquid crystal polarized interference units at different levels in liquid crystal tunable filter, according to preset middle cardiac wave
Long corresponding drive factor calculates the driving voltage of the liquid crystal polarized interference unit at different levels；Obtain the reality under the driving voltage
Measured center wavelength calculates the deviation between the actual measurement central wavelength and the preset central wavelength；Judge the deviation
Whether value is less than deviation threshold, if so, using the driving voltage as the driving of the central wavelength of liquid crystal tunable filter
Voltage；Otherwise, correction coefficient is calculated according to the actual measurement central wavelength and the preset central wavelength；It is according to the correction
Number updates the driving voltages, until the deviation is less than the deviation threshold, is become by calibration phase-delay quantity with wavelength
The function that the function and liquid crystal phase retardation amount of change change with driving voltage, based on drive factor using simulation calculation come
The driving voltage of liquid crystal tunable filter polarization interference units at different levels is generated, and to survey central wavelength and setting central wavelength
Deviation correction coefficient is calculated, automatically correct driving voltage corresponding to liquid crystal tunable filter central wavelength, improve
The accuracy rate and efficiency of liquid crystal tunable filter central wavelength calibration.
Detailed description of the invention
Fig. 1 is that a kind of liquid crystal tunable filter central wavelength that the embodiment of the present invention one provides demarcates bearing calibration process
Figure；
Fig. 2 is the method flow diagram of step S10 in Fig. 1；
Fig. 3 is that the transmission spectrum curve for the liquid crystal phase retardation amount that the embodiment of the present invention one provides acquires schematic diagram；
Fig. 4 is the liquid crystal phase retardation chromatic dispersion quantity function curve schematic diagram that the embodiment of the present invention one provides；
Fig. 5 is that the transmission spectrum curve for the stationary phase retardation that the embodiment of the present invention one provides acquires schematic diagram；
Fig. 6 is the stationary phase retardation Dispersion Function curve synoptic diagram that the embodiment of the present invention one provides；
Fig. 7 is that the corresponding driving voltage curve of any wavelength of liquid crystal polarized interference unit that the embodiment of the present invention one provides shows
It is intended to；
Fig. 8 is the deviation detection function schematic diagram that the embodiment of the present invention one provides；
Fig. 9 is the deviation schematic diagram for the central wavelength that the embodiment of the present invention one provides；
Figure 10 is the method flow diagram of step S70 in Fig. 1；
Figure 11 is that a kind of liquid crystal tunable filter central wavelength calibration means for correcting provided by Embodiment 2 of the present invention shows
Plasticity structural block diagram；
Figure 12 is the exemplary block diagram that drive factor obtains module in Figure 11；
Figure 13 is the exemplary block diagram of correction module in Figure 11.
The embodiments will be further described with reference to the accompanying drawings for the realization, the function and the advantages of the object of the present invention.
Specific embodiment
It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, it is not intended to limit the present invention.
In subsequent description, it is only using the suffix for indicating such as " module ", " component " or " unit " of element
Be conducive to explanation of the invention, itself there is no specific meanings.Therefore, " module " can mixedly make with " component "
With.
As shown in Figure 1, in the present embodiment, a kind of liquid crystal tunable filter central wavelength calibration bearing calibration, comprising:
S10, function meter is changed with driving voltage with wavelength change function and liquid crystal phase retardation amount according to phase-delay quantity
It calculates and obtains drive factor；
S20, central wavelength is set for the liquid crystal polarized interference units at different levels in liquid crystal tunable filter, according to preset
The corresponding drive factor of central wavelength calculates the driving voltage of the liquid crystal polarized interference unit at different levels；
S30, obtain actual measurement central wavelength under the driving voltage, calculate the actual measurement central wavelength with it is described preset
Deviation between central wavelength；
S40, judge whether the deviation is less than deviation threshold, if so, entering step S50, by the driving voltage
The driving voltage of central wavelength as liquid crystal tunable filter；
Otherwise, it enters step S60, correction system is calculated according to the actual measurement central wavelength and the preset central wavelength
Number；
S70, the driving voltage is updated according to the correction coefficient, until the deviation is less than the deviation threshold.
In the present embodiment, by demarcating phase-delay quantity with the function and liquid crystal phase retardation amount of wavelength change with drive
It is dry to generate liquid crystal tunable filter polarizations at different levels based on drive factor using simulation calculation for the function of dynamic voltage change
The driving voltage of unit is related to, and correction coefficient, automatic school is calculated to survey central wavelength and set the deviation of central wavelength
Driving voltage corresponding to positive liquid crystal tunable filter central wavelength improves the calibration of liquid crystal tunable filter central wavelength
Accuracy rate and efficiency.
As shown in Fig. 2, in the present embodiment, the step S10 includes:
S11, phase-delay quantity is obtained with wavelength change function, the phase-delay quantity includes liquid crystal with wavelength change function
Phase-delay quantity is with wavelength change function and stationary phase retardation with wavelength change function；
S12, liquid crystal phase retardation amount is obtained with driving voltage variation function；
S13, become with wavelength change function and the liquid crystal phase retardation amount with driving voltage according to the phase-delay quantity
Change function and calculates acquisition drive factor.
In the present embodiment, the liquid crystal phase retardation amount includes: with the acquiring method of wavelength change function
A, parallel polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing shake with analyzing is parallel, and is being polarized
Vibration and analyzing center of percussion are inserted into liquid crystal phase retardation piece, make the angle of liquid crystal phase retardation piece crystalline axis direction Yu polarizing direction
45 °, form a parallel polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in A line in Fig. 3；
B, vertical polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing and analyzing shake is vertical, and is being polarized
Vibration and analyzing center of percussion are inserted into liquid crystal phase retardation piece, make the angle of liquid crystal phase retardation piece crystalline axis direction Yu polarizing direction
45 °, form a vertical polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in B line in Fig. 3；
C, liquid crystal phase retardation chromatic dispersion quantity calculates
Interfere transmitted spectrum pole using the corresponding wavelength value of parallel polarization interference transmitted spectrum maximum and vertical polarization
It is worth corresponding wavelength value greatly, liquid crystal phase retardation chromatic dispersion quantity function curve Δ nd is calculated based on polarization interference principleLC(λ),
As shown in Figure 4.
In the present embodiment, the stationary phase retardation includes: with the acquiring method of wavelength change function
A, parallel polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing shake with analyzing is parallel, and is being polarized
Vibration and analyzing center of percussion insertion stationary phase postpone piece, make the angle of stationary phase delay piece crystalline axis direction and polarizing direction
45 °, form a parallel polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in A line in Fig. 5；
B, vertical polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing and analyzing shake is vertical, and is being polarized
Vibration and analyzing center of percussion are inserted into liquid crystal phase retardation piece, make the angle of stationary phase delay piece crystalline axis direction and polarizing direction
45 °, form a vertical polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in B line in Fig. 5；
C, the dispersion of stationary phase retardation calculates
Interfere transmitted spectrum pole using the corresponding wavelength value of parallel polarization interference transmitted spectrum maximum and vertical polarization
It is worth corresponding wavelength value greatly, stationary phase retardation Dispersion Function curve Δ is calculated based on polarization interference principle after normalization
ndQ(λ), as shown in Figure 6.
In the present embodiment, sequence driving voltage is generated using driver and drive liquid crystal polarized interference unit, pass through spectrum
Instrument measures the corresponding transmission spectrum curve of sequence voltage.It tracks and records transmission spectrum curve maximum wave corresponding with minimum
Long value variation, wavelength value with the discrete data fitting of voltage change at wavelength with the function of voltage change, by wavelength with electricity
The functional relation of buckling obtains the corresponding driving voltage of any wavelength of liquid crystal polarized interference unit, as shown in Figure 7.
In the present embodiment, according to Δ ndLC(λ) is calculatedTransmission spectrum curve maximum is
When driving voltage is from ViIncrease to VjWhen, the corresponding wavelength of maximum is from λiIt is changed to λj, i.e.,
Use drive factorTo indicate liquid crystal phase retardation amount with the variation of driving voltage.When due to no-voltageWith maximum value, as driving voltage increases, the corresponding wavelength of maximum reduces, andIt is one to pass
Subtraction function, drive factor are dimensionless numbers in (0,1) section.
In the present embodiment, liquid crystal tunable filter is composed of multistage liquid crystal polarized interference unit, liquid crystal at different levels
The filter function of polarization interference unit can be equivalent are as follows:
......
Select the stationary phase delay δ of liquid crystal polarized interference units at different levelsiLater, at different levels liquid crystal polarized by calculating acquisition
The corresponding drive factor α of any maximum wavelength of interference uniti, i.e.,
......
Bring drive factor α intoi, pass through T (λ)=T1(λ)T2(λ)......Tn(λ) curve analyzes acquisition halfwidth
(FWHM), the performance parameters such as most Out-of-band rejection ratio, transmitance, optimize drive factor α by maximum selectioni, according to driving
Factor alphaiSearch corresponding driving voltage.Any central wavelength of liquid crystal tunable filter can be automatically generated by simulation calculation
The driving voltage of required liquid crystal polarized interference units at different levels.
In the present embodiment, the step S30 includes:
The driving voltage is generated to drive liquid crystal polarized interference units at different levels using liquid crystal driver, is examined by spectrometer
The corresponding central wavelength of maximum for surveying transmission spectrum curve is actual measurement central wavelength, calculate the actual measurement central wavelength with it is described
Deviation between preset central wavelength.
As shown in figure 8, the end PC simulation calculation obtains liquid crystal polarized units at different levels in the driving of the central wavelength arbitrarily set
Factor alphaiAfterwards, corresponding driving voltage value V is searchedi, voltage V is generated using LCD drive controlleriTo drive liquid crystal at different levels
Polarization interference unit, by spectrometer detect transmission spectrum curve the corresponding wavelength of maximum and setting central wavelength it is inclined
Difference, as shown in Figure 9.
As shown in Figure 10, in the present embodiment, the step S70 includes:
S71, by the corresponding drive factor of the preset central wavelength multiplied by the correction coefficient, obtain updated drive
Dynamic coefficient；
S72, updated driving voltage is calculated according to the updated drive factor；
Actual measurement central wavelength under S73, the acquisition updated driving voltage, calculates the actual measurement central wavelength and institute
State the deviation between preset central wavelength；
Judge whether the deviation is less than deviation threshold step back to step S40, until the deviation is less than institute
State deviation threshold.
In the present embodiment, if the central wavelength of the tunable optic filter set is λd, then have
The corresponding wavelength of certain grade of polarization interference unit transmitted spectral curve maximum of the tunable optic filter of actual measurement is λr,
Since stationary phase retardation does not change with driving voltage, then have
By the corresponding wavelength X of polarization interference unit transmitted spectral curve maximumrIt corrects to λd, need to meet
Wherein c is correction coefficient, then has
Wherein, λ is wavelength；For transmission spectrum curve maximum, k is natural number；δiFor liquid crystal at different levels
The stationary phase of polarization interference unit postpones；T is filter function.
In the present embodiment, simulation calculation is obtained into liquid crystal polarized unit in the drive factor of the central wavelength arbitrarily set
αiMultiplied by after correction coefficient c c αi, search drive factor c αiCorresponding driving voltage Vi1It is set as liquid crystal tunable filter
Central wavelength driving voltage, recycle liquid crystal driver to generate and liquid crystal polarized interference units at different levels driven with the voltage,
The deviation that the corresponding wavelength of maximum of transmission spectrum curve and the central wavelength of setting are detected by spectrometer, if liquid crystal
The deviation of the central wavelength of the corresponding wavelength of maximum and setting of polarization interference unit transmission spectrum curve meets design and wants
It asks, then by Vi1The driving voltage of the central wavelength of setting as tunable liquid crystal filter.If deviation is beyond design model
Enclose, be then corrected according to preceding method, by after n times correct deviation meet the V of design requirementiNIt is filtered as tunable liquid crystal
The driving voltage of the central wavelength of the setting of wave device.
Embodiment two
As shown in figure 11, in the present embodiment, a kind of liquid crystal tunable filter central wavelength demarcates means for correcting, packet
It includes:
Drive factor obtains module 10, for according to phase-delay quantity with wavelength change function and liquid crystal phase retardation amount with
Driving voltage changes function and calculates acquisition drive factor；
Driving voltage computing module 20, for being set for the liquid crystal polarized interference units at different levels in liquid crystal tunable filter
Central wavelength calculates the driving electricity of the liquid crystal polarized interference unit at different levels according to the corresponding drive factor of preset central wavelength
Pressure；
Demarcating module 30 calculates the actual measurement central wavelength for obtaining the actual measurement central wavelength under the driving voltage
With the deviation between the preset central wavelength；
Judgment module 40, for judging whether the deviation is less than deviation threshold, if so, the driving voltage is made
For the driving voltage of the central wavelength of liquid crystal tunable filter；
Correction coefficient computing module 50 is used for when the deviation is not less than deviation threshold, according to the actual measurement center
Wavelength and the preset central wavelength calculate correction coefficient；
Correction module 60, for updating the driving voltage according to the correction coefficient, until the deviation is less than institute
State deviation threshold.
In the present embodiment, by demarcating phase-delay quantity with the function and liquid crystal phase retardation amount of wavelength change with drive
It is dry to generate liquid crystal tunable filter polarizations at different levels based on drive factor using simulation calculation for the function of dynamic voltage change
The driving voltage of unit is related to, and correction coefficient, automatic school is calculated to survey central wavelength and set the deviation of central wavelength
Driving voltage corresponding to positive liquid crystal tunable filter central wavelength improves the calibration of liquid crystal tunable filter central wavelength
Accuracy rate and efficiency.
As shown in figure 12, in the present embodiment, the drive factor acquisition module includes:
First function acquiring unit 11, for obtaining phase-delay quantity with wavelength change function, the phase-delay quantity with
Wavelength change function include liquid crystal phase retardation amount with wavelength change function and stationary phase retardation with wavelength change function；
Second function acquiring unit 12 changes function with driving voltage for obtaining liquid crystal phase retardation amount；
Drive factor acquiring unit 13 is used for according to the phase-delay quantity with wavelength change function and the liquid crystal phase
Retardation calculates with driving voltage variation function and obtains drive factor.
In the present embodiment, the liquid crystal phase retardation amount includes: with the acquiring method of wavelength change function
A, parallel polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing shake with analyzing is parallel, and is being polarized
Vibration and analyzing center of percussion are inserted into liquid crystal phase retardation piece, make the angle of liquid crystal phase retardation piece crystalline axis direction Yu polarizing direction
45 °, form a parallel polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in A line in Fig. 3；
B, vertical polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing and analyzing shake is vertical, and is being polarized
Vibration and analyzing center of percussion are inserted into liquid crystal phase retardation piece, make the angle of liquid crystal phase retardation piece crystalline axis direction Yu polarizing direction
45 °, form a vertical polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in B line in Fig. 3；
C, liquid crystal phase retardation chromatic dispersion quantity calculates
Interfere transmitted spectrum pole using the corresponding wavelength value of parallel polarization interference transmitted spectrum maximum and vertical polarization
It is worth corresponding wavelength value greatly, liquid crystal phase retardation chromatic dispersion quantity function curve Δ nd is calculated based on polarization interference principleLC(λ),
As shown in Figure 4.
In the present embodiment, the stationary phase retardation includes: with the acquiring method of wavelength change function
A, parallel polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing shake with analyzing is parallel, and is being polarized
Vibration and analyzing center of percussion insertion stationary phase postpone piece, make the angle of stationary phase delay piece crystalline axis direction and polarizing direction
45 °, form a parallel polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in A line in Fig. 5；
B, vertical polarization interference transmission spectrum curve acquisition
The polarization direction of polarizing and analyzing vibration is set, and the polarization direction for making polarizing and analyzing shake is vertical, and is being polarized
Vibration and analyzing center of percussion are inserted into liquid crystal phase retardation piece, make the angle of stationary phase delay piece crystalline axis direction and polarizing direction
45 °, form a vertical polarization interference unit.Using spectrometer collection polarization interference transmission spectrum curve, transmitted spectrum is marked
The corresponding wavelength value of curve maximum, as shown in B line in Fig. 5；
C, the dispersion of stationary phase retardation calculates
Interfere transmitted spectrum pole using the corresponding wavelength value of parallel polarization interference transmitted spectrum maximum and vertical polarization
It is worth corresponding wavelength value greatly, stationary phase retardation Dispersion Function curve Δ is calculated based on polarization interference principle after normalization
ndQ(λ), as shown in Figure 6.
In the present embodiment, sequence driving voltage is generated using driver and drive liquid crystal polarized interference unit, pass through spectrum
Instrument measures the corresponding transmission spectrum curve of sequence voltage.It tracks and records transmission spectrum curve maximum wave corresponding with minimum
Long value variation, wavelength value with the discrete data fitting of voltage change at wavelength with the function of voltage change, by wavelength with electricity
The functional relation of buckling obtains the corresponding driving voltage of any wavelength of liquid crystal polarized interference unit, as shown in Figure 7.
In the present embodiment, according to Δ ndLC(λ) is calculatedTransmission spectrum curve maximum is
When driving voltage is from ViIncrease to VjWhen, the corresponding wavelength of maximum is from λiIt is changed to λj, i.e.,
Use drive factorTo indicate liquid crystal phase retardation amount with the variation of driving voltage.When due to no-voltageWith maximum value, as driving voltage increases, the corresponding wavelength of maximum reduces, andIt is one to pass
Subtraction function, drive factor are dimensionless numbers in (0,1) section.
In the present embodiment, liquid crystal tunable filter is composed of multistage liquid crystal polarized interference unit, liquid crystal at different levels
The filter function of polarization interference unit can be equivalent are as follows:
......
Select the stationary phase delay δ of liquid crystal polarized interference units at different levelsiLater, at different levels liquid crystal polarized by calculating acquisition
The corresponding drive factor α of any maximum wavelength of interference uniti, i.e.,
......
Bring drive factor α intoi, pass through T (λ)=T1(λ)T2(λ)......Tn(λ) curve analyzes acquisition halfwidth
(FWHM), the performance parameters such as most Out-of-band rejection ratio, transmitance, optimize drive factor α by maximum selectioni, according to driving
Factor alphaiSearch corresponding driving voltage.Any central wavelength of liquid crystal tunable filter can be automatically generated by simulation calculation
The driving voltage of required liquid crystal polarized interference units at different levels.
In the present embodiment, the demarcating module includes:
The driving voltage is generated to drive liquid crystal polarized interference units at different levels using liquid crystal driver, is examined by spectrometer
The corresponding central wavelength of maximum for surveying transmission spectrum curve is actual measurement central wavelength, calculate the actual measurement central wavelength with it is described
Deviation between preset central wavelength.
As shown in figure 13, in the present embodiment, the correction module includes:
Drive factor updating unit 71, for by the corresponding drive factor of the preset central wavelength multiplied by the correction
Coefficient obtains updated drive factor；
Driving voltage updating unit 72, for updated driving electricity to be calculated according to the updated drive factor
Pressure；
Deviation updating unit 73 calculates institute for obtaining the actual measurement central wavelength under the updated driving voltage
State the deviation between actual measurement central wavelength and the preset central wavelength；
Cycling element 74 judges whether the deviation is less than deviation threshold step for returning to, until the deviation
Value is less than the deviation threshold.
In the present embodiment, if the central wavelength of the tunable optic filter set is λd, then have
The corresponding wavelength of certain grade of polarization interference unit transmitted spectral curve maximum of the tunable optic filter of actual measurement is λr,
Since stationary phase retardation does not change with driving voltage, then have
By the corresponding wavelength X of polarization interference unit transmitted spectral curve maximumrIt corrects to λd, need to meet
Wherein c is correction coefficient, then has
Wherein, λ is wavelength；For transmission spectrum curve maximum, k is natural number；δiFor liquid crystal at different levels
The stationary phase of polarization interference unit postpones；T is filter function.
In the present embodiment, simulation calculation is obtained into liquid crystal polarized unit in the drive factor of the central wavelength arbitrarily set
αiMultiplied by after correction coefficient c c αi, search drive factor c αiCorresponding driving voltage Vi1It is set as liquid crystal tunable filter
Central wavelength driving voltage, recycle liquid crystal driver to generate and liquid crystal polarized interference units at different levels driven with the voltage,
The deviation that the corresponding wavelength of maximum of transmission spectrum curve and the central wavelength of setting are detected by spectrometer, if liquid crystal
The deviation of the central wavelength of the corresponding wavelength of maximum and setting of polarization interference unit transmission spectrum curve meets design and wants
It asks, then by Vi1The driving voltage of the central wavelength of setting as tunable liquid crystal filter.If deviation is beyond design model
Enclose, be then corrected according to preceding method, by after n times correct deviation meet the V of design requirementiNIt is filtered as tunable liquid crystal
The driving voltage of the central wavelength of the setting of wave device.
It should be noted that, in this document, the terms "include", "comprise" or its any other variant are intended to non-row
His property includes, so that the process, method, article or the device that include a series of elements not only include those elements, and
And further include other elements that are not explicitly listed, or further include for this process, method, article or device institute it is intrinsic
Element.In the absence of more restrictions, the element limited by sentence "including a ...", it is not excluded that including being somebody's turn to do
There is also other identical elements in the process, method of element, article or device.
The serial number of the above embodiments of the invention is only for description, does not represent the advantages or disadvantages of the embodiments.
The above is only a preferred embodiment of the present invention, is not intended to limit the scope of the invention, all to utilize this hair
Equivalent structure or equivalent flow shift made by bright specification and accompanying drawing content is applied directly or indirectly in other relevant skills
Art field, is included within the scope of the present invention.
Claims (10)
1. a kind of liquid crystal tunable filter central wavelength demarcates bearing calibration characterized by comprising
It is driven with wavelength change function and liquid crystal phase retardation amount with driving voltage variation function calculating according to phase-delay quantity
Dynamic coefficient；
Central wavelength is set for the liquid crystal polarized interference units at different levels in liquid crystal tunable filter, according to preset central wavelength
Corresponding drive factor calculates the driving voltage of the liquid crystal polarized interference unit at different levels；
The actual measurement central wavelength under the driving voltage is obtained, the actual measurement central wavelength and the preset central wavelength are calculated
Between deviation；
Judge whether the deviation is less than deviation threshold, if so, using the driving voltage as liquid crystal tunable filter
Central wavelength driving voltage；
Otherwise, correction coefficient is calculated according to the actual measurement central wavelength and the preset central wavelength；
The driving voltage is updated according to the correction coefficient, until the deviation is less than the deviation threshold.
2. a kind of liquid crystal tunable filter central wavelength according to claim 1 demarcates bearing calibration, which is characterized in that
It is described to be driven with wavelength change function and liquid crystal phase retardation amount with driving voltage variation function calculating according to phase-delay quantity
Dynamic coefficient includes:
Phase-delay quantity is obtained with wavelength change function, the phase-delay quantity includes liquid crystal phase retardation with wavelength change function
Amount is with wavelength change function and stationary phase retardation with wavelength change function；
It obtains liquid crystal phase retardation amount and changes function with driving voltage；
Change function meter with driving voltage with wavelength change function and the liquid crystal phase retardation amount according to the phase-delay quantity
It calculates and obtains drive factor.
3. a kind of liquid crystal tunable filter central wavelength according to claim 2 demarcates bearing calibration, which is characterized in that
The actual measurement central wavelength obtained under the driving voltage, calculates the actual measurement central wavelength and the preset central wavelength
Between deviation include:
The driving voltage is generated using liquid crystal driver to drive liquid crystal polarized interference units at different levels, is detected by spectrometer saturating
The corresponding central wavelength of maximum of the curve of spectrum is penetrated as actual measurement central wavelength, the actual measurement central wavelength is calculated and is preset with described
Central wavelength between deviation.
4. a kind of liquid crystal tunable filter central wavelength according to claim 3 demarcates bearing calibration, which is characterized in that
It is described that the driving voltage is updated according to the correction coefficient, include: until the deviation is less than the deviation threshold
By the corresponding drive factor of the preset central wavelength multiplied by the correction coefficient, updated drive factor is obtained；
Updated driving voltage is calculated according to the updated drive factor；
Obtain the actual measurement central wavelength under the updated driving voltage, calculate the actual measurement central wavelength with it is described preset
Deviation between central wavelength；
Back to judging whether the deviation is less than deviation threshold step, until the deviation is less than the deviation threshold.
5. a kind of liquid crystal tunable filter central wavelength according to claim 4 demarcates bearing calibration, which is characterized in that
The liquid crystal phase retardation amount is with wavelength change function representation are as follows: Δ ndLC(λ)；
The stationary phase retardation is with wavelength change function representation are as follows: Δ ndQ(λ)；
The corresponding drive factor of the liquid crystal polarized interference unit at different levels indicates are as follows:
......
The correction coefficient is expressed as:
Wherein, λ is wavelength；For transmission spectrum curve maximum, k is natural number；δiIt is at different levels liquid crystal polarized
The stationary phase of interference unit postpones；T is filter function.
6. a kind of liquid crystal tunable filter central wavelength demarcates means for correcting characterized by comprising
Drive factor obtains module, for electric with driving with wavelength change function and liquid crystal phase retardation amount according to phase-delay quantity
Buckling function, which calculates, obtains drive factor；
Driving voltage computing module, for cardiac wave in being set for the liquid crystal polarized interference units at different levels in liquid crystal tunable filter
It is long, the driving voltage of the liquid crystal polarized interference unit at different levels is calculated according to the corresponding drive factor of preset central wavelength；
Demarcating module, for obtaining the actual measurement central wavelength under the driving voltage, calculate the actual measurement central wavelength with it is described
Deviation between preset central wavelength；
Judgment module, for judging whether the deviation is less than deviation threshold, if so, using the driving voltage as liquid crystal
The driving voltage of the central wavelength of tunable optic filter；
Correction coefficient computing module, for when the deviation is not less than deviation threshold, according to the actual measurement central wavelength and
The preset central wavelength calculates correction coefficient；
Correction module, for updating the driving voltage according to the correction coefficient, until the deviation is less than the deviation
Threshold value.
7. a kind of liquid crystal tunable filter central wavelength according to claim 6 demarcates means for correcting, which is characterized in that
The drive factor obtains module
First function acquiring unit, for obtaining phase-delay quantity with wavelength change function, the phase-delay quantity becomes with wavelength
Change function include liquid crystal phase retardation amount with wavelength change function and stationary phase retardation with wavelength change function；
Second function acquiring unit changes function with driving voltage for obtaining liquid crystal phase retardation amount；
Drive factor acquiring unit is used for according to the phase-delay quantity with wavelength change function and the liquid crystal phase retardation amount
It is calculated with driving voltage variation function and obtains drive factor.
8. a kind of liquid crystal tunable filter central wavelength according to claim 7 demarcates means for correcting, which is characterized in that
The demarcating module includes:
The driving voltage is generated using liquid crystal driver to drive liquid crystal polarized interference units at different levels, is detected by spectrometer saturating
The corresponding central wavelength of maximum of the curve of spectrum is penetrated as actual measurement central wavelength, the actual measurement central wavelength is calculated and is preset with described
Central wavelength between deviation.
9. a kind of liquid crystal tunable filter central wavelength according to claim 8 demarcates means for correcting, which is characterized in that
The correction module includes:
Drive factor updating unit, for by the corresponding drive factor of the preset central wavelength multiplied by the correction coefficient,
Obtain updated drive factor；
Driving voltage updating unit, for updated driving voltage to be calculated according to the updated drive factor；
Deviation updating unit calculates the actual measurement for obtaining the actual measurement central wavelength under the updated driving voltage
Deviation between central wavelength and the preset central wavelength；
Cycling element judges whether the deviation is less than deviation threshold step for returning to, until the deviation is less than
The deviation threshold.
10. a kind of liquid crystal tunable filter central wavelength according to claim 9 demarcates means for correcting, feature exists
In the liquid crystal phase retardation amount is with wavelength change function representation are as follows: Δ ndLC(λ)；
The stationary phase retardation is with wavelength change function representation are as follows: Δ ndQ(λ)；
The corresponding drive factor of the liquid crystal polarized interference unit at different levels indicates are as follows:
......
The correction coefficient is expressed as:
Wherein, λ is wavelength；For transmission spectrum curve maximum, k is natural number；δiIt is at different levels liquid crystal polarized
The stationary phase of interference unit postpones；T is filter function.
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