Apparatus and method for automatic focusing of a non - mydriatic fundus camera

摘要

Device for automatic focusing of a non - mydriatic fundus camera, consisting of a in the illumination beam path (1) arranged, at least one focussing mark in the infrared spectral range generating focus strength sodium marks - unit (3) with a focusing aid - setting unit (4) for the projection on the fundus oculi (6), a in the imaging beam path (7) arranged ir - sensitive, imaging sensor (9) with image processing unit (10) for the observation and recording of the fundus oculi (6) with image focusing mark, wherein the image processing unit (10) is designed such that it generates control signals so long until the image of the focussing mark the focused - state indicates, as well as a control - and evaluation unit (12), which is so designed that of the evaluation of the from the sensor (9) with image processing unit (10) recorded images of the ocular fundus (6) with image focusing mark, both actuating signals for the focusing aid - setting unit (4) as well as for a focussing - setting unit (11) in order to compensate for refractive imaging aberrations, of the imaging beam path (7) arranged main lens (8) is generated, and passed on to the latter and is to be carried out, wherein - of the control and evaluation unit (12) generates control signals and are carried out until the focused - state is reached, characterized in that the focus strength sodium marks - unit (3) is formed in the form of a two-part focussing mark in the infrared spectral region for a coincidence method, and - that the control and evaluation unit (12) is designed in such a way by the sensor (9) with image processing unit (10) recorded images of the fundus oculi (6) to evaluate with image focusing mark, in that predefined image regions, according to statistical image characteristics of the focusing mark is sought in both parts of the focusing mark be detected, in order to determine the distance therefrom, the focal position for the refractive compensation and to calculate both actuating signals for the focusing aid - setting unit (4) as well as for the focussing - setting unit (11) in order to compensate for refractive imaging errors of the main lens (8) to generate the focusing aid - setting unit (4) and the focussing - setting unit (11) to transmit.