Songcan Lai | PubMed Health

PubMed2006

An algorithm for 3-D refractive index measurement in holographic confocal microscopy.

The principle of holographic confocal microscopy is introduced in this paper. An algorithm is presented to retrieve the phase information from the holograms and calculate the refractive index of the specimen from the phase. It is shown that this algorithm can be applied to a refractive index distribution in which the variation in x and z directions can be separated. The two examples used for the simulations are a linear gradient distribution and a circular distribution, which can be found in practical situations.

Journal Article↗

PubMed2003

Miniaturized digital holography sensor for distal three-dimensional endoscopy.

A miniaturized sensor head for endoscopic measurements based on digital holography is described. The system was developed to measure the shape and the three-dimensional deformation of objects located at places to which there is no access by common measurement systems. A miniaturized optical sensor, including a complete digital holographic interferometer with a CCD camera, is placed at the end of a flexible endoscope. The diameter of the head is smaller than 10 mm. The system enables interferometric measurements to be made at speeds of as many as five reconstructions per second, and it can be used outside the laboratory under normal environmental conditions. Shape measurements are performed with two wavelengths for contouring, and the deformation is measured by digital holographic interferometry. To obtain full three-dimensional data in displacement measurements we illuminate the object sequentially from three different illumination directions. To increase the lateral resolution we use temporal phase shifting.

Endoscopes↗