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Extension of the dynamic range of liquid crystal tunable Lyot filter is demonstrated by incorporating with it a liquid crystal variable retarder as an eliminator for the third and fourth order peaks. The filter is continuously tunable in the range 500 nm to 900 nm with a nominal width in the range 50nm-100nm. Design procedure is described including the(More)
Skin cancer diagnosis depends not only on histopathological examination but also on visual inspection before and after the excision of suspected lesion. Neoplasm is accompanied with changes in birefringence of collagen, pleomorphicity, and hyperchromatic state of epithelial nuclei. These phenomena can be measured by spectral and polarization changes of(More)
A novel (to our knowledge) concept for a tunable birefringent filter with a high dynamic range is proposed and demonstrated by using a stack of liquid-crystal retarders having different thicknesses following an arithmetic sequence. Each retarder is between crossed polarizers with its optic axis oriented azimuthally at 45 degrees to the polarizer axis. The(More)
Liquid crystal (LC) devices exhibit fast and strong tuning and switching capabilities using small voltages and can be miniaturized thus have a great potential to be used with miniature optical imaging systems for biomedical applications. LC devices designed specifically for integration into biomedical optical imaging systems are presented. Using a(More)
Spectropolarimetric skin imaging is becoming an attractive technique for early detection of skin cancer. Using two liquid crystal retarders in combination with a dual-band passive spectral filter and two linear polarizers, we demonstrate the spectral and polarimetric imaging of skin tissue in the near infrared. Based on this concept, a compact prototype(More)
BACKGROUND Most physicians diagnose skin malignancy using theoretical criteria and clinical experience. Apart from dermatoscopy, noninvasive means for skin tumors' diagnosis are highly expensive and are not in daily use. We developed a simple, handy and relatively inexpensive tool for non-invasive diagnosis of skin tumors. The Differential Optical(More)
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