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An automatic focussing apparatus for microscopes includes a pair of photoelectric transducer elements disposed short of and beyond the imaging position, respectively, of an optical system which is used for the purpose of focussing. Each element is connected with a separate loop comprising an A/D con

An automatic focussing apparatus for microscopes includes a pair of photoelectric transducer elements disposed short of and beyond the imaging position, respectively, of an optical system which is used for the purpose of focussing. Each element is connected with a separate loop comprising an A/D converter which converts an output signal from the associated element corresponding to each picture element into a digital quantity, a sample-and-hold circuit, a calculation circuit which responds to the digital signal to derive an evaluation function, and an accumulator which stores the resulting value. The individual accumulators are connected with a comparison circuit, which is in turn connected with a focus control circuit controlling the optical system.

대표청구항 ▼

Automatic focussing apparatus for a microscope having a specimen stage, an optical system and a focussing mechanism therefor to bring the image of a specimen at said stage into proper focus, said apparatus comprising a pair of photoelectric transducer elements disposed respectively short of and beyo

Automatic focussing apparatus for a microscope having a specimen stage, an optical system and a focussing mechanism therefor to bring the image of a specimen at said stage into proper focus, said apparatus comprising a pair of photoelectric transducer elements disposed respectively short of and beyond the imaging position of a focussing optical system for receiving light images formed short of and beyond the imaging position of said focussing optical system; said focussing optical system including means for simultaneously directing successive picture elements towards said transducer elements; a pair of analog-to-digital converters connected with the output of respective transducer elements for converting an analog output from its associated transducer element which corresponds to each picture element into a digital quantity, a pair of sample-and-hold circuits connected with the converters for holding an output signal in the form of the digital quantity, a pair of calculation circuits for deriving one of the evaluation functions Si-Pi-1)2 or Si-Pi-2)2 where Pi represents density information of a selected picture element represented by the digital signal, and wherein i represents the location of the picture element Pi such that Pi and Pi-1 represent the density information of adjacent picture elements while Pi and Pi-2 represent density information of spaced picture elements a pair of accumulators connected with the respective calculation circuits for accumulating the calculated output, a comparison circuit for comparing the stored content of both accumulators, and a focus control circucit for operating a focussing mechanism in response to an output signal from the comparison circuit, thus adjusting the optical system to bring the image into focus.