LIGHT EMITTING DEVICE

摘要

There is provided a light emitting device with at least one radiation source, at least one radiation source for electromagnetic radiation providing at least one sensing beam during operation of the device, at least one detector for detecting the sensing beam, at least one sensing window having a contact boundary surface, wherein the detector is arranged such that during operation of the device the sensing beam on a path from the radiation source providing the sensing beam to the detector is at least once reflected at the contact boundary surface of a sensing window by total internal reflection once the contact boundary surface of the sensing window is in contact with air, and a controller communicating with the radiation source providing the operating beam and with a detector and being operable to influence operation of the radiation source providing the operating beam responsive to the sensing beam detected at the detector.