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A novel laser scanning microscope with laser videodisc optics

John Golja

Centre for Imaging and Applied Optics, Swinburne University of Technology

3.30pm, Friday 29 November 2002, Seminar Room (AR103), Graduate Research Centre, Swinburne

A novel, low-cost laser scanning microscope (LSM) has been designed and constructed with a resonant galvanometer and optics derived from laser videodisc technology. The line-scan, or x-scan mirror, consists of a torsion rod resonant galvanometer, and is incorporated into the modified optical train of the videodisc player. The frame-scan, or y-scan mirror, is a radial error-correcting mirror in the optical head assembly of the videodisc player. A diffraction-limited objective lens is attached on to the condenser lens mount of a standard optical microscope, which is also employed as the specimen stage mount.

Mechanical and electrical characterisations of the two types of scanning mirrors were undertaken. The scanning system operates in two frame-scan modes, a typical mono-directional (sawtooth) scan and a bi-directional (triangular) scan. A quadrant photodiode detection system enables acquisition of two types of imaging modes; namely the detector integral, or summing mode, and a differential phase contrast (DPC) mode. Software was developed specifically for displaying the resultant images from the acquisition board.

Two optical imaging modes are obtained from the LSM, one being the reflection mode and the other being a double-pass transmission mode. The reflection mode has been used on various types of reflective surfaces, while the double-pass transmission mode was employed in imaging biological specimens. An optical analysis of the LSM was calculated using geometric optics, Gaussian optics and diffraction optics.

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