Noncontact, 1 °C resolution temperature measurement by projection moiré interferometry

A rapid, inexpensive temperature measurement scheme, applicable across a broad temperature range, based on noncontact measurement of the expansion of a grating structure on the surface of interest is demonstrated. A simple projection moire technique is used to remotely determine the grating periodicity and, hence, the temperature. An optical Fourier transform technique is introduced to simplify the analysis. A sensitivity of ±0.5 °C for a grating length of 6 mm in a Si wafer around room temperature is demonstrated.