High-image quality, high-resolution camera with high sensitivity up to 1,100 nm

Abstract

We have developed three types of prototype cameras based on multi-purpose and DSLR models equipped with full-frame (35 mm) CMOS sensors, i.e. modified versions of the Canon ME20F-SH, EOS-1D X, and EOS 5DS. We have also made a prototype interchangeable lens that is highly transmissive in the visible and near infrared (NIR) region, based on a Canon EF 100-400 mm lens. High signal-to-noise (S/N) ratio spectral images up to 1,100 nm were observed using the following tools: the modified ME20F-SH, which features a monochromatic sensor with a 19 μm pixel pitch; the modified EF 100-400 mm lens; NIR optical bandpass filters ranging from 1,000 to 1,200 nm with 25 nm bandwidth; and a short wavelength cut-off filter that blocks light below 840 nm. This camera and lens, with a liquid crystal tunable filter (LCTF) attached, was able to clearly observe absorption bands attributed to hydroxyl groups near 960 nm in aqueous sucrose solutions. This experimental set was also applied to discrimination between dairy cream and whipped topping in combination with multivariate analysis; multi spectral data set obtained by this experimental set was processed by principal component analysis followed by a modified algorithm of independent component analysis. The Canon EOS-1D X’s 18.1 million pixel sensor was modified by introducing NIR pixels in addition to its RGB pixels. The modified EOS-1D X and the lens were able to acquire both high-image-quality photography and high-resolution NDVI (Normalized Difference Vegetation Index) in the observation of a lawn with a single press of the shutter button. This camera and lens set was also applied to observe hair in dried seaweed, producing a high-resolution NIR image in which each hair was visualized. Furthermore, a sharper image of the hair was obtained using the modified EOS 5DS and the LCTF.