CN101464190A - Varifocal full-polarization spectrum imaging detection system - Google Patents

Abstract

A zoom full-polarization spectral imaging detection system consists of a zoom optical lens, a spectral filter, two liquid crystal variable retarders (an LCVR1 and an LCVR2), a polarizer, a microspur optical lens, a charge-coupled device, an electronic driver, an image acquisition card and a computer. The imaging system of the system adopts a zoom optical system; the corresponding spectral imaging is achieved through the selection of suitable spectral filers; as the phase delay is changed by controlling the value of voltage applied to the two LCVRs, the full-polarization imaging of the system is realized; and the image signal of the target to be detected is collected by the computer and is subjected to image processing. The invention has the ability of subjecting a target to be detected to full-polarization spectrum detection within the range of visible wavelength or near infrared wavelength, and can achieve varying spatial resolutions in the same detection distance.

Description

Varifocal full-polarization spectrum imaging detection system

Technical field

The present invention relates to Varifocal full-polarization spectrum imaging detection system, especially refer to a kind of optical system spaceborne, airborne and that ground full-polarization spectrum imaging is over the ground surveyed that is used for.

Background technology

Polarization spectrum imaging is provided by information such as the physicochemical property, water cut of the surfaceness can provide about target, texture trend, surface orientation, surface conductivity, material, is with a wide range of applications and economic worth in the fields such as detection, geologic prospecting, soil analysis, environmental monitoring, resource exploration, disaster estimation, agriculture forest and husbandry development, material analysis, ocean exploitation and medical diagnosis of cloud and atmospheric aerosol.Along with the development day by day of polarization spectrum imaging Detection Techniques, development high-efficiency reliable polarization spectrum imaging detection system becomes the emphasis of domestic and international research.

In the polarization remote sensing field, external polarization Detection Techniques are comparatively ripe, and some research institutions and company have developed a lot of polarization detection instruments.The LONG WAVE INFRARED polarization imager of U.S. application technology federation, Air Force experiment chamber, Ball Aerospace Technology Co., robot calculator engineering college of Mexico State University joint research and development, adopt polarizing filter, little grid polarisation array, can obtain four width of cloth polarization information images by synchronization, and can obtain caloric information.The space flight polarization remote sensing polarization observing unit of European Space Agency/European Space Technical Center Earth Observations Programs department, the development of European Meteorological Satellite development organizations adopts two Brewster prism structures, can carry out earth ozone observation.The POLDER of France's Center For Space Research adopts polaroid, filter plate structure, and global observation is carried out in solar radiation and degree of polarization, can extract atmospheric aerosol and cloud layer information.Two view field imaging beam split polarimeters of Montana State University electronics and the development of computer engineering institute can be realized ground-to-air and surface-to-surface polarization detection.The BATC imaging Stokes polarimeter of BALL Aerospace Technology Co. development, used LCTF (liquid crystaltunable filter, LCTF) and LCVR (liquid crystal variable retarder, LCVR) electrooptic modulator, in visible-range, regulate wave band arbitrarily, filming frequency is enough high, can be used for target detection.

From domestic and international research as can be seen, the subject matter that present polarization imaging detection optical system exists is: be fixed-focus system, can only realize certain spatial resolution at same detection range, and the selected polarization components of most of detection system needs mechanical rotation when carrying out polarimetry, and the polarization detection accuracy is not high enough.

Summary of the invention

The present invention wants technology to deal with problems: a kind of Varifocal full-polarization spectrum imaging detection system is provided, this detection system has in visible and near infrared wavelength coverage, the ability of the full polarization characteristic of the accurate detection of a target, and on same detection range, can realize different spatial resolutions.

A kind of Varifocal full-polarization spectrum imaging detection system of the present invention, its technical solution: this Varifocal full-polarization spectrum imaging detection system comprises following part:

The varifocal optical lens is positioned at whole optical system foremost, is used for measured target Polaroid in its focal plane;

Filter wheel is positioned at after the focal plane of varifocal optical lens, and the optical filter that is installed on the filter wheel is used to realize spectrum beam split function;

Two liquid crystal phase place variable delay device LCVR1 and LCVR2 are positioned at after the filter wheel, by changing two magnitudes of voltage on the LCVR, can change the phase delay of incident light;

Polaroid is positioned at after the LCVR2, is used to change the polarization of incident light direction;

The microspur optical lens is positioned at after the polaroid, is used for the system's imaging first time is carried out secondary imaging;

(charge coupled device CCD), is electrooptical device to charge-coupled image sensor, is used for the light radiation intensity of measured target is converted to electric signal, and the electric signal of its output is sent into computing machine via Computer I/O card;

Electronic driver is used to control and is added in two magnitudes of voltage on the LCVR, thereby changes the phase-delay value of LCVR, and its drive output and two LCVR join, and the Communication Control end links to each other with computer by serial or USB interface;

Image pick-up card is used for the signal after the CCD opto-electronic conversion is sent into computing machine, and it is inserted in the PCI slot of computing machine;

Computing machine is used to control the magnitude of voltage that is added in LCVR, thereby changes the phase-delay value of LCVR; Gather the measured target picture signal, and institute's images acquired is handled.

Wherein, described varifocal optical lens, be positioned at whole optical system foremost, be used for measured target Polaroid in its focal plane, thereby realized the zoom of whole detection system making detection system on same detection range, can realize different spatial resolutions respectively by the zoom of self.

Wherein, described varifocal optical lens is the varifocal telephoto lens.

Wherein, described two LCVR are based on automatically controlled two refracting characteristics of liquid crystal and make, and adopt the automatically controlled light generation phase delay that can make by LCVR, need not moving component, and the response time of LCVR are short, belongs to Millisecond; Described polaroid is the accurate polaroid of being made by compacting one deck dichroic polarized material between high quality optical glass, and this accurate polaroid and two LCVR formations have the accurately polarimetry assembly of the function of 4 full Stokes vector of the detection of a target.

Principle of work of the present invention is: the spectral measurement function of system uses optical filter as beam splitter, 6 tablet filters are installed in respectively on the filter wheel with 6 optical filtering grooves, thereby by the wavelength of rotating filtering wheel change by detection system, obtain the image of target, realize the imaging spectral detecting function of system at this wavelength place.The polarimetry assembly that the full polarization detecting function of system is made up of two LCVR and accurate polaroid is realized, the polarization axis direction of adjusting accurate polaroid only allows the polarized light of a fixed-direction pass through, be added in the magnitude of voltage of LCVR by computer control, thereby change the phase-delay value of LCVR, 4 groups of different phase-delay values are set, the difference images acquired, can acquire 4 image intensity value, obtain a system of linear equations, utilize the Mueller inverse matrix to obtain the value of 4 components of full Stokes vector.The varifocal function of system realizes by detection system varifocal optical lens foremost, makes detection system can realize different spatial resolutions respectively on same detection range.

A kind of Varifocal full-polarization spectrum imaging detection system of the present invention has following advantage:

(1) this full polarization detection system is a zoom system, can realize different spatial resolutions respectively on same detection range.

The phase delay of (2) two LCVR need not moving component by Control of Voltage, and the response time is short, belongs to Millisecond, the full Stokes vector of the detection measured target that the polarimetry assembly that constitutes with accurate polaroid can be accurately and fast.

Description of drawings

Fig. 1 is that system of the present invention forms theory diagram;

Fig. 2 is a varifocal optical lens structural drawing of the present invention;

Fig. 3 is a filter wheel structural drawing of the present invention;

Fig. 4 is LCVR of the present invention phase delay synoptic diagram under different Control of Voltage;

Fig. 5 is a workflow diagram of the present invention.

Concrete label is as follows among the figure:

1, varifocal optical lens 2, filter wheel

3、LCVR1、2

4, polaroid 5, microspur optical lens 6, CCD

7, image pick-up card 8, computing machine 9, electronic driver

Embodiment

As shown in Figure 1, the present invention includes varifocal optical lens 1, optical filter 2, two LCVR, polaroid 4, microspur optical lens 5, CCD6, electronic driver 9, image pick-up card 7 and computing machine 8, the picture signal of CCD6 output is sent into computing machine 8 through image pick-up card 7, electronic driver 9 links to each other with computing machine 8 serial ports, the rotating filtering wheel can change the wavelength by detection system, obtain the image of target at this wavelength place, the polarimetry assembly is made up of two LCVR and accurate polaroid, the polarization axis direction of adjusting accurate polaroid only allows the polarized light of a fixed-direction pass through, be added in the magnitude of voltage of LCVR by computer control, thereby change the phase-delay value of LCVR, the value of 4 groups of LCVR phase delays is set, the difference images acquired, can get 4 image intensity value, obtain a system of linear equations, utilize the Mueller inverse matrix to obtain the value of 4 components of full Stokes vector, can realize the function that full-polarization spectrum imaging is surveyed, wherein, choosing of the value of 4 groups of LCVR phase delays and polaroid polarization axis direction is that good attitude matrix theory optimization according in the matrix theory gets.The focal length that changes the varifocal optical lens can be so that detection system realizes different spatial resolutions respectively on same detection range.

As shown in Figure 2, varifocal optical lens of the present invention is the varifocal telephoto lens, and its focal length variation value scope is determined by the spatial resolution changing value scope of detection system.On same detection range, when needing detection system to realize different spatial resolutions, can realize by the zoom of varifocal telephoto lens.

As shown in Figure 3, filter wheel has 6 optical filtering grooves, and 6 tablet filters can be installed, thereby by the wavelength of rotating filtering wheel change by detection system, obtains the image of target at this wavelength place, realizes the imaging spectral detecting function of system.The optional scope of the wavelength of filter plate and bandwidth is wider, can change filter plate on the filter wheel at any time according to the feature of measured target.

As shown in Figure 4, LCVR is subjected to voltage-controlled optical device, and the effect to the incident ray polarisation under different Control of Voltage has nothing in common with each other.When adding suitable voltage, LCVR can very effective control optical system in polarized state of light.Utilize two LCVR to constitute and have the accurately polarimetry assembly of the function of 4 full Stokes vector of the detection of a target with accurate polaroid.

When system installed, the polarization axis direction of adjusting accurate polaroid only allowed horizontal polarization light pass through, and the quick shaft direction of LCVR1 and LCVR2 is respectively 22.5 ° and 45 ° with respect to the angle of accurate polarization axis direction.Characterize transmitted light with the Mueller matrix operation by accurate polaroid LP plane of polarization.The available Stokes vector S of light of coming out from LP ₀=(LP) (VR2) (VR1) S _iRepresent, wherein S _i=(I, Q, U, V) be the input Stokes vector of representing by conventional symbols, that is I total light intensity of being, Q is the light intensity difference of horizontal linear polarization and perpendicular linear polarization, U is the light intensity difference of 45 ° of linear polarizations and 135 ° of linear polarizations, and V is the light intensity difference of right-hand circular polarization and Left-hand circular polarization.The Mueller matrix of accurate polaroid and two linear delay device LCVR is respectively suc as formula shown in (1), (2) and (3) in the system.

$\mathrm{LP}=\frac{1}{2}\left[\begin{array}{cccc}q+r& q-\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="A200910076358E00112.png"\; state="\{\{state\}\}">r</figure-callout>}& 0& 0\\ q-r& q+\mathrm{<figure-callout\; id="0"\; label="r"\; filenames="A200910076358E00112.png"\; state="\{\{state\}\}">r</figure-callout>}& 0& 0\\ 0& 0& 2\sqrt{\mathrm{<figure-callout\; id="0"\; label="qr"\; filenames="A200910076358E00112.png"\; state="\{\{state\}\}">qr</figure-callout>}}& 0\\ 0& 0& 0& 2\sqrt{\mathrm{qr}}\end{array}\right]---\left(1\right)$

$\mathrm{VR}1\left({\mathrm{\&delta;}}_1\right)=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& \frac{1}{2}(1+\cos \left({\mathrm{\&delta;}}_1\right))& \frac{1}{2}(1-\cos \left({\mathrm{\&delta;}}_1\right))& -\frac{1}{\sqrt{2}}\sin \left({\mathrm{\&delta;}}_1\right)\\ 0& \frac{1}{2}(1-\cos \left({\mathrm{\&delta;}}_1\right))& \frac{1}{2}(1+\cos \left({\mathrm{\&delta;}}_1\right))& \frac{1}{\sqrt{2}}\sin \left({\mathrm{\&delta;}}_1\right)\\ 0& \frac{1}{\sqrt{2}}\sin \left({\mathrm{\&delta;}}_1\right)& -\frac{1}{\sqrt{2}}\sin \left({\mathrm{\&delta;}}_1\right)& \cos \left({\mathrm{\&delta;}}_1\right)\end{array}\right]---\left(2\right)$

$\mathrm{VR}2\left({\mathrm{\&delta;}}_2\right)=\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& \cos \left({\mathrm{\&delta;}}_2\right)& 0& -\sin \left({\mathrm{\&delta;}}_2\right)\\ 0& 0& 1& 0\\ 0& \sin \left({\mathrm{\&delta;}}_2\right)& 0& \cos \left({\mathrm{\&delta;}}_2\right)\end{array}\right]---\left(3\right)$

Q and r are two heavy attenuation coefficients of linear polarizer in the formula, for desired polarization device q=1, r=0, δ ₁And δ ₂Be the phase delay of phase delay device.Because detector only produces response to light intensity, so S ₀Only need I ₀Component, I ₀Value can multiply by product matrix (VR2) every trying to achieve (VR1) with first row of matrix (LP), and the result who provides is:

$I_0=\frac{1}{2}I+\frac{1}{2}[\frac{1}{2}(1+\cos \left({\mathrm{\&delta;}}_1\right))\cos \left({\mathrm{\&delta;}}_2\right)-\frac{1}{\sqrt{2}}\sin \left({\mathrm{\&delta;}}_1\right)\sin \left({\mathrm{\&delta;}}_2\right)]Q$

$+\frac{1}{2}[\frac{1}{2}(1-\cos \left({\mathrm{\&delta;}}_1\right))\cos \left({\mathrm{\&delta;}}_2\right)+\frac{1}{\sqrt{2}}\sin \left({\mathrm{\&delta;}}_1\right)\sin \left({\mathrm{\&delta;}}_2\right)]U---\left(4\right)$

$-\frac{1}{2}[\frac{1}{2}\cos \left({\mathrm{\&delta;}}_1\right)\sin \left({\mathrm{\&delta;}}_2\right)+\frac{1}{\sqrt{2}}\cos \left({\mathrm{\&delta;}}_2\right)\sin \left({\mathrm{\&delta;}}_1\right)]V$

In order to find 4 components of input Stokes vector, 4 groups of different phase-delay value (δ are set ₁, δ ₂0 ° of)=(, 35 °), (0 °, 145 °), (180 °, 145 °) and (180 °, 35 °), images acquired obtains 4 I ₀Value obtains a system of linear equations, utilizes S _iInverting S _i=(B) ^-1I ₀Obtain four 4 components of incident light, wherein (B) each row is to postpone (δ corresponding to 4 groups ₁, δ ₂) top each equation in variable I, Q, the coefficient of U and V.

Workflow diagram of the present invention as shown in Figure 5.At first, the focal length of preposition variable focal length optical system is set, rotating filtering takes turns to required detection wavelength, and the phase-delay value by two LCVR of computer installation is 0 all, obtains the image of target on this wavelength, thereby has realized the imaging spectral detecting function of system; Change the phase-delay value of LCVR1 and LCVR2 then successively, obtain 4 light intensity values of image on this wavelength, separate 4 Stokes polarized component values that system of linear equations just can get target, thereby finished the full-polarization spectrum property detection of target; According to the requirement of different spatial resolutions, change the focal length of varifocal optical lens, repeat aforesaid operations, can realize that the full-polarization spectrum of same detection range different spatial resolutions is surveyed.

Claims (3)

1, Varifocal full-polarization spectrum imaging detection system is characterized in that: this system comprises following part:

The varifocal optical lens is positioned at whole optical system foremost, is used for measured target Polaroid in its focal plane;

Filter wheel is positioned at after the focal plane of varifocal optical lens, and the optical filter that is installed on the filter wheel is used to realize spectrum beam split function;

Two liquid crystal phase place variable delay device LCVR1 and LCVR2 are positioned at after the filter wheel, by changing two magnitudes of voltage on the LCVR, can change the phase delay of incident light;

Polaroid is positioned at after the LCVR2, is used to change the polarization of incident light direction;

The microspur optical lens is positioned at after the polaroid, is used for the system's imaging first time is carried out secondary imaging;

Charge-coupled image sensor is electrooptical device, is used for the light radiation intensity of measured target is converted to electric signal, and the electric signal of its output is sent into computing machine via Computer I/O card;

Electronic driver is used to control and is added in two magnitudes of voltage on the LCVR, thereby changes the phase-delay value of LCVR, and its drive output and two LCVR join, and the Communication Control end links to each other with computer by serial or USB interface;

Image pick-up card is used for the signal after the charge-coupled image sensor opto-electronic conversion is sent into computing machine, and it is inserted in the PCI slot of computing machine;

Computing machine is used to control the magnitude of voltage that is added in LCVR, thereby changes the phase-delay value of LCVR; Gather the measured target picture signal, and institute's images acquired is handled.

Described varifocal optical lens, be positioned at whole optical system foremost, be used for measured target Polaroid in its focal plane, thereby realized the zoom of whole detection system making detection system on same detection range, can realize different spatial resolutions respectively by the zoom of self.

2, Varifocal full-polarization spectrum imaging detection system according to claim 1 is characterized in that: described varifocal optical lens is the varifocal telephoto lens.

3, Varifocal full-polarization spectrum imaging detection system according to claim 1, it is characterized in that: the electrically conerolled birefringence characteristic that described two LCVR are based on liquid crystal is made, adopt the automatically controlled light generation phase delay that can make by LCVR, need not moving component, and the response time of LCVR is short, belongs to Millisecond; Described polaroid is the accurate polaroid of being made by compacting one deck dichroic polarized material between high quality optical glass, and this accurate polaroid and two LCVR formations have the accurately polarimetry assembly of the function of 4 full Stokes vector of the detection of a target.

Images