AN APPARATUS AND METHOD FOR DETECTING PHOTOLUMINESCENT LIGHT EMITTED FROM A SAMPLE

The present invention provides an apparatus for detecting photoluminescent light emitted from a sample, said apparatus (200; 300) comprising at least one light source (210; 310, 318), which is configured to emit light of a first and a second wavelength towards a sample comprising photoluminescent particles, wherein said first wavelength is an excitation wavelength for inducing photo-luminescent light from said photoluminescent particles, and wherein said second wavelength is longer than said first wavelength and for gathering background noise information from said sample. The apparatus further comprises a photo-detector (206) for detecting light incident on the photo-detector (206); and an interference filter (204; 304) arranged on the photo-detector (206), wherein the interference filter (204; 304) is configured to selectively collect and transmit light towards the photo-detector (206) based on an angle of incidence of the light towards the interference filter (204; 304), wherein the interference filter (204; 304) is configured to selectively transmit supercritical angle light from the sample towards the photo-detector (206) and suppress undercritical angle light from the sample.