What part of the plate reader is responsible for collecting light photons?

The correct answer involves understanding the role of each component in a plate reader regarding light collection. The component responsible for collecting light photons is the photomultiplier tube, which is a highly sensitive device used to convert light into electrical signals. It operates by amplifying the electrical signal produced when light photons strike its surface, making it particularly adept at detecting low levels of light.

While light guides are important in directing the light from the sample to the detector, they do not themselves collect photons but rather facilitate the movement of light. The photodiode and detector element also play vital roles in converting light into an electric signal, but in a different manner and with different sensitivity levels compared to the photomultiplier tube. The photomultiplier tube, being more sensitive, is crucial in applications where detecting faint light signals is necessary, such as in biomedical assays and research. Therefore, the photomultiplier tube is the component specifically responsible for the primary task of collecting light photons effectively in a plate reader setup.