1 April 2003 Filtering characteristics and grating images of multiphase grating optical low-pass filters
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Optical Engineering, 42(4), (2003). doi:10.1117/1.1554404
Although the grating optical low-pass filter (GOLF) has many advantages over the traditional birefringent low-pass filter, it is not adopted in commercial digital cameras because the shadow image of the grating is visible, especially when the F-number of a camera is large. We design and manufacture grating optical low-pass filters with multiple phases to compare their filtering characteristics and shadow images. From the simulation of the Fresnel diffraction pattern of a 1-D multiphase grating, we obtain the optimum width and phase of each grating step that minimizes the visibility of the Fresnel diffraction pattern. We design 2-D multiphase structures by extrapolating the 1-D structure. Four types of GOLF are manufactured with a semiconductor process and installed into a digital camera to compare grating images. We find that the visibility of grating images can be reduced by increasing number of phase steps.
Yong-Ho Oh, Jai-Cheol Lee, Sungwoo Lim, Shi-Ho Kim, Chun-Soo Go, "Filtering characteristics and grating images of multiphase grating optical low-pass filters," Optical Engineering 42(4), (1 April 2003). https://doi.org/10.1117/1.1554404


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