Real time determination of the optical thickness and topography of tissues by chromatic confocal microscopy

In this work, a miniaturized probe of chromatic confocal microscopy to measure the optical thickness and topography of tissues is presented. The experimental model is based on the principle of focus multiplexing by wavelength encoding due to a phase Fresnel lens. The device is composed of a point polychromatic illumination system, a wavelength-height codification system of confocal microscopy and a spectral detection system. The illumination system has a broad and continuum spectrum and it is constituted by the combination of a high energy pulsed laser and an air-silica microstructured optical fibre. The first two systems form a wavelength segment on the device output. The coding of the optical thickness and the topography is based on the detection of the most intense spectral components coming from the interphases of the organic membranes. The measurement sensitivity is related to the width of the spectral response, which depends on the resolving power of the dispersive element and the detection system. The experimental results and a brief discussion of the resolution criterion and the perspectives of the work are provided.