For many applications, the blue laser sensor is vastly superior to conventional models with a red laser diode. The blue-violet laser light does not penetrate the measuring object, but forms a small point on its surface. The short wavelength of blue laser light (405 nm) offers significant benefits for measuring organic materials or glowing metal surfaces. This becomes apparent when examining the processes within a combustion engine where a thermo element measures the exhaust gas temperature within the engine. The laser triangulation displacement sensor optoNCDT 1700BL measures the vibrations of the thermo element in the engine manifold. Measurements using conventional laser sensors with red laser light are adversely affected especially when it comes to red-hot metals, because the reflected intensive light in the red spectral range falls within the sensor's sensitivity range. The optoNCDT 1700BL, however, effectively filters stray light using high-quality interference filters, as the blue-violet laser light works within the opposite range of the spectrum. The vibrations can be measured with a sampling frequency of 2.5 kHz and analysed via a PC interface.