An optical system includes a sample carrier receiving region configured to receive a carrier carrying a sample for processing, a source that emits an excitation signal having a wavelength within a first predetermined wavelength range, and a first set of optical components that direct the excitation signal along an excitation path to the sample carrier receiving region, wherein radiation having a wavelength within a second predetermined wavelength range is emitted from the sample carrier receiving region in response to receiving the excitation signal. The system further includes a detector configured to detect the emitted radiation and generates a signal indicative of a power of the detected radiation and a second set of optical components that directs the emitted radiation along a collection path to the detector and a power meter that measures a power of the radiation emitted from the sample carrier receiving region and generates a signal indicative thereof.