In situ optical surface temperature measuring techniques and devices

A temperature sensor that has a thermally conducting contact with a surface that emits electromagnetic radiation in proportion to the temperature of the contact is disclosed. The sensor has a resilient member attached to the contact and configured to extend the contact toward the object to be measured. A first light waveguide is attached to the contact and is configured to transmit the electromagnetic radiation from the contact. The sensor has a guide with a bore formed therein that the first waveguide is insertable into. When the contact is moved, the first waveguide moves within the bore. A second waveguide is attached to the guide such that a variable gap is formed between the ends of the first waveguide and the second waveguide. Electromagnetic energy from the first waveguide traverses the gap and can be transmitted by the second waveguide. The guide allows the first waveguide to move with the contact in order to ensure that the contact is fully engaged with the surface of the object.