Optimization of fiber optic probe distance for biomedical spectroscopy

We present a theoretical model to maximize the illumination and collection efficiency in designing fiber optic probes for biomedical spectroscopy measurement. This model is in general applicable to probes with single or multiple fibers. We investigated a number of probe configurations and find that contact measurement is very inefficient for multi-fiber probes. Contact measurement is a good choice for single-fiber probes, but for multi-fiber probes, there is an optimal probe distance. By carefully choosing the probe and sample distance, the signal can be enhanced by 5-10 fold. Experiments demonstrate the distance dependence of collection efficiency in multi-fiber probes.