Near-infrared spectroscopy (NIRS) based techniques are utilised in quantifying changes of chromophore concentrations
in tissue. Particularly, non-invasive in vivo measurements of tissue oxygenation in the cerebral cortex are of interest. The
measurement method is based on illuminating tissue and measuring the back-scattered light at wavelengths of interest.
Tissue illumination can be realised using different techniques and various light sources. Commonly, lasers and laser
diodes (LD) are utilised, but also high-power light emitting diodes (HPLED) are becoming more common. At the
moment, a wide range of available narrow-band light sources exists, covering basically the entire spectrum of interest in
brain tissue NIRS measurements.
In this paper, in the centre of our interest are LDs and HPLEDs, because of their affordability, efficiency in terms of
radiant flux versus size and easiness to adopt in in vivo medical applications. We compare characteristics of LDs and
HPLEDs at specific wavelengths and their suitability for in vivo quantifying of different tissue chromophore
concentration, particularly in cerebral blood flow (CBF). A special focus is on shape and width of the wavelength bands
of interest, generated by the LDs and HPLEDs. Moreover, we experimentally study such effects as, spectroscopy cross
talk, separability and signal-to-noise ratio (SNR) when quantifying tissue chromophore concentration. Chromophores of
our interest are cytochrome, haemoglobin and water. Various LDs and HPLEDs, producing narrow-band wavelengths in
the range from 500 nm to 1000 nm are tested.