FocalCheck fluorescent microspheres calibration of laser scanning 'scopes

Molecular Probes' FocalCheck fluorescent microspheres are designed for examining the alignment, sensitivity and stability of confocal laser-scanning microscopes. They are particularly useful for confirming the optical sectioning thickness (z-resolution) in three-dimensional imaging applications. The sharp ring stains exhibited by the FocalCheck microspheres produce a striking visual representation of instrument misalignment or other aberrations, making them ideal reference standards. The excitation/emission maxima of the different stains are designed to be especially suitable for testing and aligning confocal laser scanning microscopes with multiple laser lines and detection channels.

FocalCheck dyes are localised within the polystyrene beads and are therefore protected from environmental factors, making FocalCheck microspheres brighter and much more photostable than conventional surface-stained beads.

They are produced using a proprietary method in which a fluorescent dye is allowed to penetrate the microsphere to a limited depth. The resulting beads have a well-defined dye layer that, when viewed in cross section in the confocal laser scanning microscope, appears as a fluorescent ring of varying dimensions depending on the focal plane.

The products are available in seven different colour configurations and, in addition to the bead suspensions, FocalCheck microspheres are available premounted on microscope slides.