Tunable Bandpass Filters
The ubiquitous techniques of fluorescence and Raman imaging and spectroscopy rely heavily on spectrally precise, high-quality and high-throughput optical filter technologies. As both fluorescence and Raman-based techniques move from traditional R&D-based environments into medical and clinical (diagnostic) settings, even higher demands are placed on system performance. Therefore, it is necessary to continue to improve system components and architectures to meet the demanding challenges often encountered in biological applications.
One simple and straightforward means to do this without a complete system redesign and overhaul is to conceive of new spectrally precise, high-quality and high-throughput optical filters that can perform in more than one mode of operation. A recent advance in this area has been the development of thin-film interference filters that are tunable over a wide range of wavelengths with little or no sacrifice in filter performance, i.e. transmission characteristics.