Our goal was to develop a simple method, easy to use by any individual, and relatively inexpensive. The idea is indeed a simple one. Incident light fluoresces a transparent reference material, and the fluorescent light is polarized. The transmitted incident light then fluoresces the sample, whose fluorescent light is not polarized. Next, a filter removes the incident light and selects the wavelengths needed for analysis.
Light then passes through a dual polarizer, half polarized vertically and half horizontally.
The eye views the light through an adjustable polarizer, which is rotated until both sides of view are of equal brightness. The angle of rotation is related by a calibration curve to the concentration of the analyte. The reference material is not necessarily the same as the analyte. Polarization of the reference fluorescence is achieved with a polarizer or by doping an oriented stretched film with a fluorophore. The only electronics are the power supply and excitation source.