What is the primary function of dichroic mirrors in flow cytometry?

Dichroic mirrors play a crucial role in the process of flow cytometry by selectively reflecting certain wavelengths of light while allowing others to pass through. This characteristic enables them to effectively separate signals from different fluorescent dyes used to label cells in a sample. As a result, dichroic mirrors facilitate the detection of multiple populations or markers within a single sample by directing the appropriate wavelengths to their respective detectors.

When light from the excitation source strikes a dichroic mirror, only the wavelengths of light that are reflected—typically those corresponding to the emission spectra of the fluorochromes being used—are directed toward the detectors. Conversely, other wavelengths are either transmitted through or reflect back to be used elsewhere in the system. This selective reflection thereby enhances the signal-to-noise ratio and improves the overall resolution of the flow cytometric analysis.

By acting in this manner, dichroic mirrors ensure that the instrumentation can accurately detect the fluorescence signals without interference from other wavelengths, which is essential for obtaining precise and reliable data in flow cytometry applications.