Advances in uncooled technology at BAE SYSTEMS

Performance model for uncooled infrared bolometer arrays and performance predictions of bolometers operating at atmospheric pressure

“…(1)-(9) correctly predict these contributing NETD parts when the infrared bolometer and system design parameters are set to the values shown in Table 1. All values in Table 1 are typical values for the respective parameters used in uncooled infrared bolometer arrays [4][5][6][7][8][9][10][11][12]20].…”

“…(1)-(9) was validated and benchmarked using published values for the contributing NETD parts from a state-of-the-art uncooled infrared bolometer array [10,11]. This array consists of 640 · 480 bolometer pixels made of vanadium oxide (VO x ).…”

“…(24) has to be divided with a factor of 2 when estimating the NETD for the bolometer array [5,8,15]. The pixel pitch of the bolometer array is 28 lm · 28 lm, the bolometer pixel fill factor is b = 62%, the total thermal conduction between each bolometer and its surroundings is G ¼ 3:7 Â 10 À8 W K , the thermal conduction between each bolometer and its surroundings by emitted infrared radiation is G radiation ¼ 0:18 Â 10 À8 W K , the thermal mass of the bolometer membrane is C ¼ 4:3 Â 10 À10 J K , the thermal bolometer time constant is s = 11.7 ms, the bolometer bias voltage is U bias = 2 V, and the image read-out frequency (imaging frame rate) is f i = 30 Hz [10,11]. The infrared bolometer array is operated in a vacuum atmosphere and the F-number of the infrared optics is F = 1.…”

“…The noise equivalent temperature difference (NETD) is one of the most important performance parameters for infrared imaging systems and is defined as the difference in temperature between two side-by-side blackbodies of large lateral extent which, when viewed by the infrared imaging system, gives rise to a difference in signal-to-noise ratio of 1 in the electrical outputs of the two halves of the array, viewing the two blackbodies. Infrared imaging systems based on uncooled bolometer arrays can today reach NETDs of as low as 25 mK with a F-number of the infrared optics of F = 1 [1,[9][10][11][12]. A NETD of 80 mK-200 mK is sufficient for many commercial infrared imaging applications [2,3].…”

“…In this paper, we present a calculational model for the NETD, including the relevant noise contributions. The NETD model is benchmarked with published values from existing state-of-the-art uncooled vanadium oxide bolometer arrays [10,11]. The NETD model is used to evaluate possible system and bolometer design improvements.…”