DEVELOPMENT OF TWO- AND THREE-WAVEBAND COLOR-MIXING BINOCULAR AND ITS APPLICATION

Authors: DING, FUJIAN - UNIV OF KY, VISITING SCI; Chen, Yud; Chao, Kuanglin - Kevin Chao

Submitted to: Applied Optics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2007
Publication Date: 4/23/2008
Citation: Ding, F., Chen, Y.R., Chao, K. 2008. Development of two- and three-waveband color-mixing binocular and its application. Applied Optics. 47(4):043201-043209.

Interpretive Summary: Band ratio techniques, particularly those utilizing two or three wavebands, have often been used to enhance the detection of targets from a background or to classify different target types based on color and/or contrast. The band ratios are often implemented through multispectral imaging systems that use beam splitters and several band-pass filters at different wavelengths along separate light paths leading to 2 or 3 separate CCD sensors. Computer algorithms then mathematically calculate the band ratios. Multispectral imaging systems are, in general, expensive and complicated. A low-cost optical device that can perform similar implementation of two- and three-band ratio techniques without the costlier hardware needed for multispectral imaging would be preferred for some applications. In previous papers, we showed that two- and three-band color-mixing techniques could perform two- and three-band ratios that normally are implemented in multispectral imaging systems to enhance detection of targets from a background or identification of multiple targets by color or contrast. In this paper, we present and test prototypes of color-mixing binoculars using color-blindness test cards. The demonstration shows that low cost color-mixing binoculars could greatly enhance visual target identification. This information is important to optical engineers who are interested in designing low cost inspection and detection devices for target detection and classification for food safety, security, and sanitation; resource assessments; and environment quality monitoring.

Technical Abstract: In previous papers, we showed that two- and three-band color-mixing techniques could be used to achieve results optically equivalent to two- and three-band ratios that are normally implemented using multispectral imaging systems, for enhancing identification of single target types against a background and for separation of multiple targets by color or contrast. In this paper, we present and test prototypes of color-mixing binoculars using color-blindness test cards. The demonstration shows that the color-mixing binoculars could greatly enhance visual target identification. Target identification of color blindness cards was improved by using binoculars fitted with filters at 620 nm and 650 nm for two-band color-mixing; this wavelength pair selection was based on the criterion of uniform background. Target identification using a different set of color blindness test cards was also improved with the use of binoculars fitted with filters at 450 nm, 520 nm, and 632 nm for three-band color-mixing; this wavelength set selection was based on the criterion of maximum chromaticness difference. These experiments show that color-mixing binoculars can significantly enhance visual inspection for some applications.