Microdisplay-Based Intraoral 3D Scanner for Dentistry

Up to now, Microdisplays are mainly used in multimedia applications or head-mounted displays. Due to their interesting properties, these displays open more and more alternative application fields, for example, in optical metrology. Projection lenses for this application area have to be specially designed, because the requirements for these systems differ completely from those for multimedia applications. The lenses must have very low geometrical image distortion and they have to be adapted to small objects and/or image distances. On the other hand, they often work with light sources with small spectral bandwidths; consequently they do not need to be corrected for chromatic aberrations. In addition, the numerical aperture (NA) has to be large enough to collect and transfer as much light as possible. Secondary the size of the projection lens has to be as small as possible to ensure compact measurement systems. All these requirements lead to a compromise in optical lens and system design. Within this paper, the development and realization of a 3D-scanner for the registration of dental surfaces directly inside the patient's mouth is presented. The advantages of such an intraoral scanning system are the reduced pain level for the patient and the absence of extensive intermediate steps. The production of prosthesis can be performed directly after measurement. Thus a quality improvement can be obtained as well as a reduction of the efforts in time and costs.