Thermocouples embedded in the tool used during light cutting verify that temperatures measured on the surface of the tool with the thermal camera are indicative of internal temperatures. Steel workpiece, 300 m/min surface speed. Thermal movie on the left is 100 frames per second. Field of view is about 1 mm wide. Visible light movie in the center is 100 frames per second. Field of view is about 2 mm wide. Camcorder movie on the right is 60 frames per second. Plot on bottom shows embedded thermocouple temperatures and a once per revolution resolver signal. For more information, see the NIST publication "Recent Experiments Assessing the Uncertainty of Metal Cutting Temperature Measurements When Using the NIST High-Speed Dual-Spectrum Optical System".