An easy-to-construct, cost-effective, and versatile microspectrometric system, employing a circular variable filter as a continuous wavelength scan monochromator, is presented. This simple system includes a single microscope optics, a single photodetector, and a spinning glass plate in conjunction with signal processing electronics, which allows a variety of microspectrometric operations at the cellular level. Three modes of operation, such as double-beam, double-beam derivative, and single-beam wavelength modulated derivative, are provided by minor rearrangements of the optics and the electronic modules. Some spectra of living cells are also presented to demonstrate the system performance.
