The primary function of the interrogation point in a flow cytometer is to illuminate cells with laser light. This is a critical step in the process of flow cytometry. At the interrogation point, cells pass through a focused laser beam that excites the fluorescently labeled antibodies or dyes attached to the cells. This illumination allows for the detection of emitted light at various wavelengths, which corresponds to the different fluorescent signals from the dyes.
The process begins with the flow of the sample, where individual cells pass through the interrogation point one at a time. The focused laser light interacts with the fluorescent markers on the cells, causing them to emit light that is then captured by detectors. This information is fundamental as it allows for the identification and characterization of cell populations based on their light-scattering properties and fluorescence profiles.
The other options represent important processes in flow cytometry, but they are not the primary function of the interrogation point. Amplifying the voltage pulse pertains to signal processing that occurs after data acquisition, while digitizing the cell data involves converting the analog signals into a digital format for analysis. Collecting spectral data is part of the overall detection process following illumination but does not reflect the primary role of the interrogation point itself.