A laser displacement sensor based on the triangulation method is capable of high-speed measurement, has a long working distance, and has a wide measurement range, so it can be used for distance measurement, vibration measurement, positioning measurement, form measurement, etc. However, speckles are generated in the image spot because the laser, which is coherent light, is used as the light source. It is known that the center of gravity of the image spot changes due to this speckle pattern, resulting in a change in displacement. The displacement fluctuation due to speckle is considered to be related to the NA of the light receiving lens, the triangulation angle of the receiving lens, the wavelength of the light source, and the surface textures of the irradiation spot. In this study, we varied conditions of these elements and measured micro form. As a result, it was found that the displacement fluctuation decreased with increasing NA and triangulation angle. Regarding the wavelength of the light source, it was possible to reduce the displacement fluctuation by shortening the wavelength. It was also found that the displacement fluctuation differs depending on the submicro topograpy of the irradiation spot. These results are important in designing the laser triangulation sensor.
