A CCD spectrophotometer to quantitate the concentration of chromophores in living tissue utilising the absorption peak of water at 975 nm.
Optical spectroscopy has long been used to study the oxygenation of living tissue in-vivo. It is possible to detect concentration changes of naturally occurring chromophores whose absorption spectra are affected by the presence of oxygen, such as haemoglobin and the cytochrome enzymes.
A tunable wavelength filter was proposed and demonstrated by using the ultraviolet nanoimprint technique. It consists of a Bragg grating in polymer waveguides and a heating electrode. The creation of the grating was substantially simplified with the introduction of a smart imprint stamp containing a waveguide pattern integrated with the grating pattern. The center wavelength of the filter was successfully tuned by taking advantage of the thermooptic effect in polymers, which was induced by supplying electrical power to the electrode. For the fabricated device, a transmission dip of ∼15dB and a 3dB bandwidth of 0.8nm were obtained at the Bragg wavelength of ∼1560nm. The achieved thermooptic tuning rate was ∼0.28nm∕mW, while the center wavelength was shifted from 1560nm to 1558nm with the electrical power consumption of 7mW.