Detection system and method

A method of detecting an optical signal from a luminescent material applied to or incorporated within an object, comprising:

• providing a detection system comprising at least one light source which generates light, as excitation light, which illuminates at least a region of the object, at least one detector which detects light, as collection light, from the object when illuminated by the excitation light and provides an output signal having a signal intensity in response to an intensity of the collection light;
• and
• controlling the output signal to have a signal intensity within a predetermined range or at substantially a constant value, or post-processing the output signal to extract the output signal at a signal intensity within a predetermined range or at substantially a constant value,
• wherein the system further comprises:
• an optical probe assembly which comprises a fiber and a probe which is optically connected to the fiber so as to transmit the excitation light to and collect the collection light from the object, wherein the fiber comprises at least one excitation fiber element through which the excitation light is delivered to the probe,
• a plurality of collection fiber elements, disposed radially outwardly of the at least one excitation fiber element through which the collection light is delivered to the at least one detector, and
• at least one intensity regulator for regulating an intensity of the collection light which is collected by the at least one detector, the at least one intensity regulator being a liquid crystal, which, by application of a bias voltage, regulates the intensity of the collection light,
• wherein the at least one intensity regulator is configured to maintain the intensity of the output signal of the at least one detector at a constant value;
• and
• wherein a measured lifetime decay of the luminescent material is substantially constant.