Abstract: The invention provides a method by which an instrument can automatically measure the absolute value of fluorescence polarization, FP, despite instrumental offsets, with no a priori knowledge what the actual FP values should be. The invention specifically provides a method for determining multiple G factors to accurately determine the FP values of each probe in samples containing two or more probes.

Abstract: A sample having a plurality of probe molecules is illuminated with at least one beam of excitation light that is linearly polarized along a first axis, thereby effecting fluorescence emission in a plurality of spectral bands. The intensity of a first component of fluorescence emission that is polarized along the first axis, as well as the intensity of a second component of fluorescence emission that is polarized along an orthogonal second axis, is measured for each of said plurality of spectral bands. These measurements are represented as a measurement vector M. Since each probe emits some limited amount of light in the characteristic band of another probe, this results in cross-talk between probes. The measurement vector is therefore corrected using an instrument response matrix A, which is generated by measuring the flux output of control samples which each have only a single probe species.

Abstract: A liquid crystal cell is described which includes adaptive means to relieve hydrostatic pressure and means for restraining the aperture portion of the cell, and which may be assembled together with thick members such as precision windows, or may be built into optical assemblies incorporating several cells placed optically in series, such as tunable filters or multiple-cell optical switches, without defeating the pressure-relief mechanism.

Abstract: A fluorescence imaging system for epi-illumination wherein the usual dichroic beamsplitter is replaced by a polarizing beamsplitter (PBS). The sample is excited with light that is linearly polarized to a significant degree, and fluorescent emission light is collected in the orthogonal linear polarization state. Excitation light that is scattered or reflected by the sample is rejected by the PBS, while the desired emission light is captured for imaging by a detector. By eliminating the usual dichroic beamsplitter member, the imaging system removes the barriers to multi-spectral imaging that such members conventionally impose.