Physikalisches Institut, J. W. Goethe University Frankfurt, 60438 Frankfurt, Germany.
Institute of Applied Electrodynamics and Telecommunications, Vilnius University, 10257 Vilnius, Lithuania.
Sensors (Basel). 2020 Jul 22;20(15):4087. doi: 10.3390/s20154087.
This work presents, to our knowledge, the first completely passive imaging with human-body-emitted radiation in the lower THz frequency range using a broadband uncooled detector. The sensor consists of a Si CMOS field-effect transistor with an integrated log-spiral THz antenna. This THz sensor was measured to exhibit a rather flat responsivity over the 0.1-1.5-THz frequency range, with values of the optical responsivity and noise-equivalent power of around 40 mA/W and 42 pW/ Hz , respectively. These values are in good agreement with simulations which suggest an even broader flat responsivity range exceeding 2.0 THz. The successful imaging demonstrates the impressive thermal sensitivity which can be achieved with such a sensor. Recording of a 2.3 × 7.5-cm 2 -sized image of the fingers of a hand with a pixel size of 1 mm 2 at a scanning speed of 1 mm/s leads to a signal-to-noise ratio of 2 and a noise-equivalent temperature difference of 4.4 K. This approach shows a new sensing approach with field-effect transistors as THz detectors which are usually used for active THz detection.
这项工作展示了我们所知的首例完全使用人体发射辐射在较低太赫兹频率范围内进行的被动成像，采用的是宽带非制冷探测器。该传感器由带有集成对数螺旋太赫兹天线的 Si CMOS 场效应晶体管组成。该太赫兹传感器的测量结果表明，在 0.1-1.5-太赫兹的频率范围内具有相当平坦的响应率，光响应率和噪声等效功率的值分别约为 40 mA/W 和 42 pW/Hz。这些值与模拟结果非常吻合，模拟结果表明甚至更宽的平坦响应率范围超过 2.0 太赫兹。成功的成像演示证明了这种传感器可以实现令人印象深刻的热灵敏度。以 1 毫米 2 的像素尺寸、1 毫米/秒的扫描速度，成功记录了一只手的手指大小为 2.3×7.5 厘米 2 的图像，得到的信噪比为 2，噪声等效温差为 4.4 K。这种方法展示了一种新的传感方法，其中场效应晶体管用作太赫兹探测器，通常用于主动太赫兹检测。
