The optics of the BD FACSCanto II system consist of an excitationsource with up to three lasers, a blue (488-nm,air-cooled,20-mW solid state), a red (633-nm, 17-mW HeNe) and aviolet (405-nm, 30-mW solid state). Laser excitation opticsilluminate cells in the sample and collection optics directlight scatter and fluorescence signals through spectral filtersto the detectors.

Excitation

Theexcitation optics consist of multiple fixed wavelength lasers,fiber optics up to the beam-shaping prisms, and achromaticfocusing lenses that produce spatially separated beamspots in the flow cell. Each lens focuses the laser light intothe gel-coupled cuvette flow cell. Since the optical pathwayand the sample core stream are fixed, alignment is fixedfrom day to day and from experiment to experiment withno need for user intervention.

Emission

Theemission signals are transmitted from the flow cell to thedetector arrays, an octagon for the blue and a trigon eachfor the red and the violet laser signals. The octagon containsfive PMTs and detects light from the 488-nm blue laser.A PMT in the octagon collects side scatter signals. The trigonscontain two PMTs each and detect light from the 633-nmred and the 405-nm violet lasers.