Shuhei Shibata

Real-time Stokes polarimeter using three polarized beam splitter (Conference Presentation)

This paper describes real-time, very small and cheap Stokes polarimeter using three polarized beam splitters (PBSs). Each s1, s2 and s3 of Stokes parameters is measured by the PBSs. However this technique has to separate three beams keeping unknown incidental polarization state. To overcome this problem, three same normal beam splitters (BSs) are possible to separated two beams keeping polarized state. An alignment of three BSs is set orthogonal in transmission part and reflection part. In transmission part, the polarization state after two BSs can be canceled change of polarization state of first BS by change of second orthogonal BS. In reflection part is same theory. If you set two pear of this keeping polarization beam splitter, you can separate three beams keeping incidental polarization state. After separated beams, three PBS can measure Stokes parameters easily. At first we checked effect of the keeping polarization beam splitter using spectoscopic Mueller matrix polarimeter. We got Mueller matrixes having max 3.3% value of transmission and reflection from unit matrix during from 450nm to 700nm. In second we checked Stokes parameters after a rotating polarizer and a quarter wave plate in this Stokes polarimeter. In two condition results, an error had 5.6%. Finally we checked measurement speed of this real-time Stokes polarimeter using rotating quarter wave plate. From this result this Stokes polarimeter is possible to measure Stokes parameter in 15Hz. This measurement speed depends on detection speed of six PIN photodiodes and transfer speed of AD convertor.

Microscopic type of real-time uniaxial 3D profilometry by polarization camera

This paper introduces a novel polarization structured light pattern projector was done by taking into account the unique characteristic of the pixelated camera and a spatial light modulator (SLM) used. Height variations of reflective samples are retrieved by using fringe contrast modulation on an uniaxial configuration. By placing a special retardance pattern on the SLM, the pixelated camera will detect a phase shifted sinusoidal pattern where later its contrast change will be used to retrieve the height information of the sample under study. The presented system takes into account the defocus change obtained by the height variation of the sample by encoding the information on the fringe contrast of the projected structured light pattern by the SLM. The final purpose of this work is to present a single shot 3D profilometry system based in fringe contrast analysis. Experimental results of a moving glass slide are presented.

Realtime birefringence mapping by polarization camera

Recently, there is a requirement to visualize birefringence distribution by an internal stress and an orientation of the polymer materials in the field of materials and biomedical engineering. A real time measurement of two dimensional birefringence distribution has been proposed by the polarization camera whose adjacent 4 pixels of the image sensor have 45°of increment azimuthal of linear polarizer. There is a limitation of dynamic range of retardance up to 90° because of circular polarization for incident light. This report proposes to expand to measurement range of retardation up to 180° by two shot intensities which are captured in case of 0° and 45° of azimuthal direction of a quarter wave plate installed before a polarization camera.