%0 Journal Article
%T Optical System for Bispectral Imaging in Mid-IR at 1000 Frames per Second
%A Marija Strojnik
%A Gonzalo Paez
%J Advances in Optical Technologies
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/905870
%X We propose, evaluate, and demonstrate the performance of an IR/optical double-image experimental setup where we capture two simultaneous images of a single object, in two different spectral bands, using a single detector array. With this arrangement, we may observe rapidly changing phenomena, at a rate of more than 1000 frames per second, without the loss of the spatial information about the test subject. We describe the optical system to perform simultaneous imaging in IR for slightly inclined optical axes. We verify the actual performance by applying the experimental method to flame analysis in the mid-IR to determine the combustion efficiency. 1. Introduction Several methods to measure the combustion efficiency have been presented recently to decrease the amount of undesirable by-products and utilize prudently a nonrenewable resource. Among them, we may mention the infrared (IR) cameras to detect the detailed temporal evolution [1] and interferometric techniques to assess the airflow and heat travel throughout the flame volume [2]. The applications with IR cameras allow studying the flame evolution; however, they only record the nontransparent imaginary surface within the flame volume that emits the radiation. Another shortcoming of this technique is that the combustion is a volume effect [3]. The radiation has to travel through the volume where some of its components are attenuated. Furthermore, combustion is time- and position-dependent phenomenon, even after the apparent steady state has been achieved. Another technique that has been successfully implemented to measure the temporal dependence of an established flame is the lateral shearing interferometry. The fringe distribution at the time of its capture indicates the flow of the heated gases. For many applications, the spatiotemporal information is even more important than the spectral one. Some multispectral imaging techniques already exist [4]. However, they require expensive and sophisticated equipment for the acquisition, storage, and processing of data. They include, for example, hyperspectral imaging, available for the Earth, the ocean, and the atmospheric monitoring from mobile platforms [5]. Their usage restricts or even limits the frame rates and introduces novel focal plane layouts [6]. They often incorporate motion as a design parameter, with carefully controlled velocity vector [7]. An alternate approach has been to redistribute the spatial information into the optical fibers, and then to analyze each fiber individually [8]. This is a flexible light conduct to move image to the
%U http://www.hindawi.com/journals/aot/2013/905870/