Fluorescence measurements are required in many biology (chlorophyll and carotenoid), biomedical (fluorescence diagnosis of malignancies) and environmental applications.

Fluorescence measurements typically need a high sensitivity setup. For most fluorescence applications the amount of fluorescence energy emitted is only 3% of the amount of excitation light energy. The fluorescence light is of a lower energy (higher wavelength) than the excitation energy and is usually scattered light (emits energy in all directions).

Most important consideration for the setup is to prevent excitation light to enter the spectrometer.

This can be done with different methods, where one does not exclude the other:

1. Use an LED light source for excitation (small bandwidth), emitting no energy at fluorescence wavelength.
2. Use an interference band pass or low pass filter in combination with 13 HLS 101 light source for high output, small bandwidth excitation.
3. Make sure that the optical path for excitation light and fluorescence are 90 degrees perpendicular. This way the excitation light will not enter the receiving fiber.

A typical setup for fluorescence measurements is given below:

Components used in the fluorescence measurement setup: