摘要 : We combine newly developed InP HEMT amplifiers operating at 670 GHz with a zero-bias diode (ZBD) in order to investigate limits on passive imaging performance possible with fully uncooled, direct-detection technology. Noise-equiva... 展开 We combine newly developed InP HEMT amplifiers operating at 670 GHz with a zero-bias diode (ZBD) in order to investigate limits on passive imaging performance possible with fully uncooled, direct-detection technology. Noise-equivalent temperature difference (NETD) values under 2 K are found for reference conditions (30 Hz modulation). However, noise spectra continue to fall approximately as out to “knee” frequencies of several hundred hertz (Hz) and spectral densities of K/Hz for the current, somewhat gain-starved, amplifiers. The amplifier alone contributes 0.043 K/Hz. These results indicate that modest-sized, rapidly scanned arrays should provide real-time, passive imaging—desired for standoff security screening and other applications—with the same image quality as cryogenic bolometer arrays. 收起