Light polarization state modulation and detection apparatuses and detection method
Disclosed are a light polarization state detection apparatus, a detection method and a light polarization state modulation method. The light polarization state detection apparatus comprises a lens with a variable birefringence feature as an optical phase modulator, a polarizer as a SOP analyzer, a plurality of common lenses and a CCD as imaging devices, and a data processing and displaying unit. The SOP detection apparatus uses wide special birefringence distribution of birefringence optical elements such as a GRIN lens to obtain the Stokes parameters of light to be measured by CCD single frame imaging, and can rapidly accurately measure the SOP. The SOP detection apparatus is simple in structure, lower in cost without containing any motion parts and electrical modulation devices, and is a fully static full Stokes parameters SOP detection apparatus.
1. A light polarization state detection apparatus, comprising a polarizer, an imaging lens, a CCD and a data processing apparatus arranged in a light path in sequence and a data transmission line connected between the CCD and the data processing apparatus; wherein the apparatus further comprises a lens with a variable birefringence feature, which can receive measured incident light and cause emergent light rays to generate spatial phase modulation of SOP of a light field and then enter the polarizer, light rays of different phases are subjected to polarization interference after passing the polarizer and generate an interference pattern, and interference fringes are projected on the CCD, recorded and transmitted to the data processing apparatus; the data processing apparatus calculates SOPs of different incident light according to the shapes of different interference patterns to which the SOPs of different incident light corresponds; the lens with the variable birefringence feature is a device having certain birefringence parameters with certain spatial retardance distribution, including a birefringence value and an optical axis direction.
2. The light polarization state detection apparatus according to claim 1 , wherein the data processing apparatus is an external computer or a combination of a memorizer, a singlechip and a display screen packaged in the SOP detection apparatus.
3. The light polarization state detection apparatus according to claim 1 , wherein the lens with the variable birefringence feature is a GRIN lens.
4. The light polarization state detection apparatus according to claim 3 , wherein one GRIN lens is arranged to realize SOP single point detection, or more GRIN lenses are arranged to form a mxn lens array and realize measurement in a SOP plane, each GRIN lens corresponds to one point for measurement to finally obtain spatial SOP distribution of m×n size, wherein m and n are positive integers.
5. The light polarization state detection apparatus according to claim 3 , wherein the retardance distribution of the GRIN lens covers retardance of 0˜180 degrees and a fast axis angle of −90˜90 degrees.
6. The light polarization state detection apparatus according to claim 3 , wherein the SOP detection apparatus is capable of being applied to an ellipsometer, a Mueller matrix measurement instrument and a polarization remote sensing apparatus.
7. A light polarization state detection method, comprising the following steps:
A, causing a light beam to be measured to enter a light inlet of a detection apparatus, wherein incident light has a certain SOP;
B, causing the incident light to enter a lens with a variable birefringence feature to generate spatial phase modulation of SOP of a light field;
C, causing the light emergent from the lens with the variable birefringence feature to enter a polarizer, wherein the light of different phases generates polarization interference after passing the polarizer and generate an interference pattern;
D, causing the light to enter a CCD, wherein interference fringes are projected and recorded on the CCD;
E, calculating SOPs of different incident light according to the shapes of different interference patterns to which the SOPs of different incident light corresponds.
8. The light polarization state detection method according to claim 7 , wherein the method further comprising a step F:
displaying a Poincare sphere representing the SOP and the corresponding elliptical polarization parameters and a corresponding polarization degree in the user interface, thereby vividly displaying a polarization measuring result.
9. The light polarization state detection method according to claim 7 , wherein the lens with the variable birefringence feature is a GRIN lens.