Multimodality of an optical system implies the use of one or more optical techniques to improve the system's overall performance and maximum utility. In this article, we demonstrate a multimodal system with oblique illumination that combines two different techniques; fluorescence micro‐endoscopy and spectroscopy simultaneously and can be utilized to obtain diverse information from the same location of biological sample. In present system, use of graded index (GRIN) rod‐lens makes it highly compact and oblique incidence decouples illumination geometry with collection geometry, preventing CCD cameras from saturation and reduces number of optical elements, thereby making system further miniaturized and field‐portable. It also overcomes the disadvantages of undesired reflections from different optical elements. The experimental results of simultaneous imaging and spectroscopy of the biological samples are presented along with quantitative spectroscopic parameters; peak wavelength shift, area under the curve and full width half maximum (FWHM). The spatial resolution, spectral resolution and field of view of the system are found to be 4.38 μm, 0.5 nm and 2.071×1.5480.25emmm2, respectively. Furthermore, we have obtained the red shift for cancerous oral tissue with respect to normal oral tissue 5.79 ± 1.071 nm. This could be important indicator for oral cancer screening.

In this paper, we demonstrate the white light phase shifting interferometer employed as whole slide scanner and phase profiler for determining qualitative and quantitative information over large field-of-view (FOV). Experiments were performed on human erythrocytes and MG63 Osteosarcoma cells. Here, we have recorded microscopic images and phase shifted white light interferograms simultaneously in a stepped manner. Sample slide is translated in transverse direction such that there exists a correlation between the adjacent frames, and they were stitched together using correlation functions. Final stitched image has a FOV of 0.24 Â 1.14 mm with high resolution ~0.8 μm. Circular Hough transform algorithm is implemented to the resulting image for cell counting and five-step phase shifting algorithm is utilised to retrieve the phase profiles over a large FOV. Further, this technique is utilised to study the difference between normal and anaemic erythrocytes. Significant changes are observed in anaemic cells as compared to normal cells.

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We report a three-dimensional surface profilometry with extended range of height measurement using synthetic wavelength scanning interferometry without any tunable filters, wavelengthtuning lasers, or grating elements. Here, we have used inexpensive multiple color light emitting diodes (LEDs) and operate them sequentially one by one or combination of two or more colors simultaneously to generate synthetic wavelength light source for illumination. Multiple color LED light source was synthesized and entire visible range from violet to deep red color was covered. A wide range of synthetic wavelengths were obtained. Experiments were performed on industrial objects and interferograms were recorded using Mirau type interferometer. Five step phase shifting algorithm was used to recover the phase maps which can be further utilized for 3D height measurement of the specimen. A simple phase subtraction method was used to reconstruct the phase map at synthetic wavelength thus extending the range of step-height measurement. The present system provides extended range of height measurement from subwavelength to tens of wavelengths. Experimental results of 3D-surface profile measurements of a Si-IC chip and a standard step object are presented. The present system does not require expensive multiple color filters or any wavelength scanning mechanism along with a broadband light source.

Development of multi-modal early-stage oral-cancer screening system can reduce the mortality rate of oral-cancer. In the present study, we combined the autofluorescence with fluorescence endoscopic imaging with spectroscopy simultaneously.