Samenvatting

Raman spectroscopy is an optical technique that is based on the inelastic scattering of light. It is non-invasive, fast, objective and easy to use. These traits make it an ideal tool for use in medical diagnosis.

Melanoma is the deadliest form of skin cancer. Currently, melanomas are visually diagnosed by general practitioners or dermatologists. All skin lesions that are suspected of being melanoma are excised. However, only a small percentage of those excisions is actually a melanoma. This indicates that some excisions could be prevented. It is also reported that some melanomas are missed during clinical diagnosis, further emphasizing the need for an easy-to-use and objective tool to aid doctors in their diagnosis. Raman spectroscopy could be such a tool.

Santos et al. have developed a focused-beam Raman spectroscopy setup that measures Raman spectra of excised skin lesions. It uses a novel InGaAs detector to measure in the High Wavenumber spectral region using a Near Infrared (976 nm) laser to decrease laser-induced tissue fluorescence that might otherwise overwhelm the typically very weak Raman signal. However, in order to adapt the setup for in vivo use and eventually clinical use, the optical layout with a focused-beam geometry had to be expanded with a fiber-optic probe, thus enabling a flexible solution to perform Raman measurements directly on the skin of the patient.

This thesis focuses on the adaptation, feasibility and verification of a fiber-optic adapter using a single fiber probe for measurements. To do this, a convenient adapter that could be removed and replaced easily to be able to compare the existing to the adapted setup had to be designed first. Calculations were done to find the requirements and limitations of such an adapter and the construction was then outsourced to the engineering department.

Once the removable adapter was available, the setup was re-aligned and optimized for use with the fiber-optic probe. Tests were done to approximate the sampling depth of the fiber probe in skin tissue, which was up to about 300 μm. This depth is sufficient for early melanoma detection. The adapter was found to produce results that were repeatable to within less than one percent.

Finally, spectra obtained using the single-fiber probe were compared to spectra obtained with the existing focused-beam setup. The results showed that the signal-to-noise ratio was consistently significantly higher using the focused-beam setup. However, the fiber adapter consistently showed a slightly lower average level of noise. It is still possible that spectra taken with the fiber adapter are of sufficient quality to be