Epson Develops Optical Low Pass Filter for Low Moire, Thinner Cameras
With a new design, the Epson OLPF promises reduced moiré, while enabling future cameras to be lighter and thinner.
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**Sept. 7, 2007* – Imaging manufacturer Epson Toyocom Corp. today announced it is developing a Optical Low Pass Filter (OLPF) for digital cameras. With a new design, the Epson OLPF promises reduced moiré, while enabling future cameras to be lighter and thinner.
Current OLPFs use three quartz plates to separate light rays in an attempt to reduce moiré. Since the three plate system does not always provide equal separation at particular wavelengths, some moiré can still persist. Moiré shows up as irregular patterns, an adverse effect common when photographing fabrics and textiles. The linear patterns are superimposed on a pixel array of a CCD or CMOS image sensor and produce moiré when spatial frequencies are narrower than the pixels. The quartz on the filter plates is intended to divide the light rays to hit the pixels and create an accurate representation of geometric patterns and overall image quality.
To eliminate moiré altogether, Epson’s proposed OLPF will use two quartz plates with a new wide-band phase retardation film inserted in between the two plates. The dual plate system, as opposed to traditional three-plate designs, will result in uniform light separation across the whole light spectrum, thus reducing moiré, according to a company press release.
Because the new Epson design uses two plates instead of three, the overall OLPF weight and size is decreased, enabling digital cameras to be lighter and thinner. Epson also points out the lighter design makes the new OLPF better equipped to handle CCD-shifting for image stabilization and dust reduction if implemented.
The Epson OLPF will be exhibited at CEATEC JAPAN 2007 in October.