Conoscopic holography systematic error processing by means of gaussian filters

This work analyses the directional effect shown by the point clouds when digitizing with a conoscopic holography (CH) sensor. The asymmetric shape of the laser spot for this sensor yields that directionality appears along the greatest spot length and it occurs repeatedly under different working conditions. To study this effect of the sensor, several tests were performed on a surface machined by EDM with a very uniform and isotropic finish, so that the directional effect should not appear actually. This ensures that the effect is a systematic factor related to the sensor and feasible to be compensated. A Gaussian filter is used with this purpose. The results found before and after applying the filter were compared with those obtained by a confocal microscope, which was used as reference due to its better metrological performance.