| 摘要 |
PURPOSE:To make possible the sure detection of focus state even for any object performing the specified operations based on the detection outputs of the optically symmetrical photoelectric elements forming arrays and standardizing correlation output functions. CONSTITUTION:The object light focused by an objective lens 1 goes through the field lens 2 in the position conjugate with the fixed focal plane formed by a film and reimaging lenses 3, 4 and images on the optical symmetrical 1st, 2nd photoelectric element arrays 5, 6. The opposing elements p1', p2 and p2'... of the arrays 5, 6 generate respectively the detection signals x1 and x1', x2 and x2'... which become equal at the focusing. Based on these detection signals, a signal processing circuit 7 perform the operations by formulas I, II to calculate correlation outputs IN, ID and determine the standardized correlation function I0 = IN/ID. This function I0 becomes the symmetrical numerical value in corresponding to the deviations in the front focus and rear focus directions irrespective of the target object, thus the focus state may be surely detected for any object. |
