Imaging fluorometer for time resolved fluorescence

An imaging system for time resolved fluorometry of chemical, biological and medical samples provided on a containing medium where they are to be subjected to illumination, causing them to emit light, the imaging system comprising:

• an illumination source which can be modulated from substantially full intensity at the samples to less than approximately 1% of full intensity in a time of less than approximately 100 microseconds;
• an illumination system providing illumination from the source to an area in the vicinity of the samples which can be larger than a microscope field of view;
• a lens to collect light emitted from samples contained within the illuminated area;
• an image formation device located such that light from the samples, passing through the lens, impinges on the device and the device produces a representation of an image of the sample emissions;
• a shutter placed between the samples and the image formation device, comprising a structure which can be made opaque (off) or transparent (on), with an on-off period shorter than approximately 100 microseconds and with a contrast ratio between on and off in excess of approximately 100:1;
• and
• a control device for setting the on-off times of the illumination source and the open/close times of the shutter.