A Miniature Focus Sensor

The ability to rapidly measure the focus of images acquired by optical systems is important in many imaging applications. Itek Optical Systems, building on its extensive wave-front sensing and adaptive optics capability, has developed an electro-optic focus sensor directly mounted to a Nikon Camera. The sensor operates by measuring the relative position of the image formed by two halves of the optical aperture. The measurement is performed using a scanning technique and a processing algorithm implemented by digital electronics. Details of the sensor design with results of its operation are presented.