Multispectral Classification With Bias-Tunable Quantum Dots-in-a-Well Focal Plane Arrays

Abstract

Mid-wave and long-wave infrared (IR) quantumdots-in-a-well (DWELL) focal plane arrays (FPAs) are promising technology for multispectral (MS) imaging and sensing. The DWELL structure design provides the detector with a unique property that allows the spectral response of the detector to be continuously, albeit coarsely, tuned with the applied bias. In this paper, a MS classification capability of the DWELL FPA is demonstrated. The approach is based upon: 1) imaging an object repeatedly using a sequence of bias voltages in the tuning range of the FPA and then 2) applying a classification algorithm to the totality of readouts, over multiple biases, at each pixel to identify the "class" of the material. The approach is validated for two classification problems: separation among different combinations of three IR filters and discrimination between rocks. This work is the first demonstration of the MS classification capability of the DWELL FPA. Index Terms-Bias tunability, dots-in-a-well (DWELL), infrared (IR) detector, multispectral (MS) classification, quantum-dots, rock classification.

Implementation of IR spectral target sensing algorithm in synthesizable logic

“…focal plane array (FPA), the readout integrated circuit ach pixel value in the FPA torage and processing unit. cene with three IR optical ability [2] was validated by for pairs of objects in Fig. f bias confirms that the FPA nts of the objects in a scene he device.…”

“…f bias confirms that the FPA nts of the objects in a scene he device. It is to be noted er such as a microbolometer main constant as a function scenes captured as bias voltage is are raw data and bottom ones are ntensity dependence [2]. Despite the self-tunability of the detecto spectral diversity than the non-tunable collected data still involves a high level of red due to the fact that the detector offers broadband and coarse resolution tuning th narrowband and high resolution tuning.…”

“…For spectroscopy problem, sets of algori continuously combined with outputs of p photocurrents), reconstructing a s ction of biases [2].…”

A novel readout circuit for on-sensor multispectral classification

“…Figure 1.b shows the impact of changing the applied bias voltage on the spectral response of the DWELL detector. Nonetheless, the spectral response of the DWELL photodetector at each bias voltage is 1-2 μm broad and has significant overlap with the spectral response associated with other bias voltages [3]. The spectral-tuning algorithm reported in [2] aimed to address the spectral overlap by forming a weighted superposition of photocurrents, obtained from using different biases, that optimally estimates (in the least-square sense) the ideal narrow-band photocurrent that would be obtained if we were to use a broadband detector to probe the same target of interest through a physical spectral filter having the desired narrow band.…”

“…To circumvent these drawbacks, our group presented a novel algorithm to perform multispectral imaging and classification by the utilization of the continuous bias tunability of the dot-in-well (DWELL) infrared photodetector [2], [3]. Figure 1.b shows the impact of changing the applied bias voltage on the spectral response of the DWELL detector.…”