(Abbreviated DIAL thermometer. ) An active remote sensor that measures temperature using a laser. To measure temperature, a DIAL thermometer transmits three wavelengths: one on an oxygen absorption band, one off the band, and one at the transition wavelength in between. With this technique, the concentrations of oxygen in various energy states can be measured. Many of the high rotational energy states of oxygen are temperature dependent, allowing temperature to be inferred from the DIAL measurements. This method requires very high accuracy, spectral resolution, and stability of the laser transmitter and detector, which are characteristics that are almost achieved at present.