OPTICAL SENSOR

A sensor for measuring a property comprises: a radiation source, a detector and a sensing element. The radiation source is operable to produce a radiation beam. The detector is provided with a detecting surface for receiving radiation and outputting a signal in dependence on the received radiation. An aperture extends through the detector from the detecting surface to an opposed surface. The sensing element is operable to receive radiation and to reflect at least a portion of the radiation so as to form a reflected radiation beam, one or more properties of the reflected radiation beam being dependent on one or more properties to be measured. The radiation source and the sensing element are disposed on opposite sides of the detector such that the radiation source is arranged to direct the radiation beam through the aperture to the sensing element and the sensing element is arranged to direct the reflected radiation beam to the detecting surface of the detector. 种用于测量性质的传感器，包括：辐射源、检测器以及感测元件。辐射源可操作成产生辐射束。检测器设有用于