Apparatus and method for fluorescence excitation and detection

An apparatus comprising:

• one or more light sources for providing excitation light for fluorescence excitation at an observation spot along an optical axis for excitation, wherein the optical axis for excitation is a light path for the excitation light when it reaches the observation spot;
• an optical collection element for collecting fluorescence light generated by the excitation light at two or more different observation spots into two or more different measurement channels with an optical axis for collecting non-parallel to the optical axis for excitation of each of the one or more light sources, wherein the fluorescence light generated at different observation spots is collected to different measurement channels by the optical collection element;
• and
• two or more optical detectors, at least one for each of the two or more measurement channels, for detecting fluorescence from the fluorescence light collected by the optical collection element, wherein the two or more optical detectors are not along the optical axis for excitation.