Brake discs must take up and dissipate the entire kinetic energy of the vehicle when it is slowed down or stopped. The high amount of energy absorbed expresses itself as heat, which makes it start to glow under the heavy load. The disc can deform while braking as more energy is absorbed. The full extent of this deformation can be measured with the new optoNCDT 1700 BL. The high infrared portion of the light from the incandescent disc means that this measurement cannot be made with a red laser. The wavelength of the blue laser, however, is sufficiently far from that of the red laser to allow reliable measurements to be made. An appropriate sensor design prevents damage to the sensor during the measurement process.