Adjustable active optical low-pass filter

This paper presents an active optical low-pass filter (AOLPF) capable of changing the resolution of an imaging system on demand in order to remove aliasing noise from a sampling image. This is advantageous over conventional optical low-pass filters, which are fixed image-blurring optical components that are built into the imaging system, in order to remove aliasing in the image. Furthermore, conventional filters smear images regardless of the presence or lack of high spatial frequency, which can exceed the Nyquist limit of the sensor. On the contrary, the proposed AOLPF can dynamically adjust the modulation transfer function of an imaging system to eliminate aliasing artifacts. In addition, this filter can be turned off in the absence of high spatial frequency to maximize resolution and prevent unnecessary blurring of the sampling image. (C) 2012 Optical Society of America