The present disclosure relates to an optical sensing module, a system and a method for operating the optical sensing system. The optical sensing module includes a light emitter that emits a sensing light in a specific wavelength range and a photodiode unit. The photodiode unit includes a first photodiode used to sense a first wavelength light, a second photodiode used to sense a second wavelength light, and a third photodiode used to sense a third wavelength light. The optical sensing module implements a proximity sensor by operations of the second photodiode and the third photodiode, or a biometric sensor by operations of the first photodiode, the second photodiode, and the third photodiode. The photodiode unit receives a reflected light from an object to be detected so as to determine if the object is proximal, and then determine whether or not the proximal object is human skin.

Aspects of the present disclosure provide improved fluorescence imaging techniques suitable for fluorescence-based analysis (e.g., sequencing) of an excited sample. Some aspects relate to directing an imaging aperture of a fluorescence imaging device towards a sample well region and capturing an image of the sample well region. Some aspects relate to selecting a sample well region and capturing an image of the selected sample well region. Some aspects relate to, during at least a portion of performing a controlled cleavage of a terminal amino acid in a first sample well, capturing a fluorescence image of a second sample well. Some aspects relate to setting a duration of imaging by and/or a location of an imaging aperture of a fluorescence imaging device. In some embodiments, aspects of the present disclosure provide for faster, less expensive, and/or greater control over fluorescence imaging and analysis of a sample.