Human Detection by Optical Readout Thermal Imaging Sensor using Evaporated Eu(TTA)₃

Abstract

This paper presents the design, fabrication and evaluation of an optical readout infrared thermal imaging sensor for human detection using vacuum evaporated Eu(TTA)₃ phosphor. Eu(TTA)₃ is served as an infrared (IR)-to-visible converter, which emits temperature dependent luminescence under specific ultraviolet (UV) excitation. The temperature sensitivity of luminescence intensity from Eu(TTA)₃ was measured as about -2.1%/℃. An optical readout system was designed to measure the luminescence changes of the sensor pixels. Eu(TTA)₃ on the sensor pixels is excited by a light emitting diode (LED) with 355 nm wavelength, and a visible luminescence map on the sensor pixels is projected onto a charge-coupled-device (CCD) camera. Thermal images of human were successfully obtained by using a 76 × 98 imaging sensor array with a carefully designed IR optics. The noise analysis shows that the noise-equivalent temperature difference (NETD) of the system is about 1.8 K.