3D tracking optical system

In order to observe particles moving in 3 dimensions, such as colloidal particles or living cells in their natural environment (i.e. without any mechanical link to a substrate), an optical tracking system is required to link the observation system to the observed target. A 3D tracking optical microscope has been developed to such purpose. It provides a fixed image of the specimen in the middle of the field of view, during the free movement of the sample in its environment. The system consists in an inverted optical microscope with internal custom optics, and the relevant electronics. The instrument can modulate the field of view around a choosen target and reconfigure the internal optical elements in order to lock the image on the target. Target identification is based on its brightness contrast with the background. A photodetector, in a confocal configuration, provides an electrical signal containing information on target position. Such position is available for analysis in analog format. On the same confocal channel, the possibility has been demonstrated of building, with the aid of external image forming equipment, a 3D confocal image of the specimen.