Abstract: In an ophthalmological measurement method and apparatus, a laser beam of predetermined diameter is projected to the eye fundus and movement of a speckle pattern formed by light scattered by blood cells in blood vessel is detected by a photosensor as fluctuation in speckle light intensity to produce a speckle signal. The speckle light intensity will fluctuate more rapidly with a smaller output from the photosensor when cell velocities are high, while a low cell travel speed will decrease the lowering of the output therefrom. The speckle signal thus mirrors the travel speed of the blood cells in the eye tissues. The differences in the speckle signal are used to identify the blood vessel for automatic tracking of the blood vessel or for measurement of its diameter.

Abstract: In an ophthalmological measurement method and apparatus, a laser beam of predetermined diameter is projected to the eye fundus and movement of a speckle pattern formed by light scattered by blood cells in blood vessel is detected by a photosensor as fluctuation in speckle light intensity to produce a speckle signal. The speckle light intensity will fluctuate more rapidly with a smaller output from the photosensor when cell velocities are high, while a low cell travel speed will decrease the lowering of the output therefrom. The speckle signal is integrated to produce an integrated speckle signal which is evaluated in terms of a rate of change to discriminate edges of a blood vessel. The integrated speckle signal is used to identify the blood vessel for automatic tracking of the blood vessel or for measurement of its diameter.

Abstract: In an autofocus apparatus for an imaging means such as a TV camera, an object image signal is produced by an imaging means and a focusing operation is conducted automatically by moving a focusing lens so as to maximize a high frequency component of the image signal. Automatic focusing operation is commenced only when the level of the image signal has remained smaller than the threshold value for longer than a prescribed period of time, whereby no unnecessary automatic focusing operation is conducted when the level of the high frequency component decreases because of movement of the camera or the object it is imaging.

Abstract: In an ophthalmological measurement method and apparatus, a laser beam of predetermined diameter is projected to the eye fundus and movement of a speckle pattern formed by light scattered by blood cells in blood vessel is detected by a photosensor as fluctuation in speckle light intensity to produce a speckle signal. The speckle light intensity will fluctuate more rapidly with a smaller output from the photosensor when cell velocities are high, while a low cell travel speed will decrease the lowering of the output therefrom. The speckle signal is then processed to derive therefrom its center of gravity, which is taken as a center of a blood vessel to identify the blood vessel. This enables the blood vessel parts to be identified with high accuracy and to be tracked automatically.