Gilden Photonics Ltd.’s fluoroSens is a single-photon-counting fluorimeter that produces a signal-to-noise ratio of 3000:1. The 150-W xenon arc lamp does not photobleach the biological sample. The system includes the excitation source operating over the 200- to 2600-nm spectral range, monochromators, a detector and Windows software. The XYZ bulb, rear mirror and lamp focus adjustment are factory-prealigned. The monochromators have a Czerny-Turner design, a 300-mm focal length and a triple-grating turret. Stray light performance is 1:105. The excitation wavelength is 350 nm, spectral bandwidth is 5 nm, and integration time is 1 s. A reference detector for corrected excitation and emission spectra is standard, and a transmission detector for checking sample stability is available as an option.