1. Optical low-pass filters (OLPF) are mainly for high image quality by eliminating screen effect, which was popular in CCD or CMOS array detector image systems. OLPF was designed by crystal birefringence characteristic, and depends on various CCD specification requirements. For high quality demand, crystal would design by different thickness, incidence angle, and pieces stacking.
2. Usually, there are anti-reflecting coatings for increasing transmittance, which also prevent ghost image. Meanwhile, IR cutting coating will properly press infra-ray for IR sensitive CCD. COT also accepts custom designed specification for IR cutting coating.
Please refer to the attachment.
Taiwan
