In high-quality digital maging systems, optical low-pass filters (OLPF) are used to eliminate color Moire fringes. An OLPF cuts off the lens MTF above the sampling frequency of the imager resulting an overall MTF curve that approximates a step function in spatial domain. IR cut-off function is often incorporated into OLPF as well. See CCD/CMOS lens selection guide for discussion of OLPF and its impact on image quality.
OLPFs are made of several cemented layers of optical quartz material. An IR cut-off coating and anti-reflection coating are applied to the external surfaces. If the IR cut-off filter type is absorptive, the IR glass is inserted between the quartz layers. Custom OLPF sizes and designs are also available.
Please contact OPTICS CONCEPT support team for details for more information.
