Human Life Signs Detection Using High-Sensitivity Pulsed Laser Vibrometer

We demonstrate experimentally the detection, in a remote and noncontact manner, of human life signs using a high-sensitivity pulsed laser vibrometer. The high surface displacement detection sensitivity of the photo-electromotive-force (photo-EMF) pulsed laser vibrometer, combined with its tolerance to the presence and moderate temporal variations of optical speckles in the light beams, allows the detection of human heartbeats, breathing, and gross physical movement from essentially any part of a human subject's surface, even in the presence of clothing, all the while without limiting the interrogation points to specific locations like the chest and carotid areas. In contrast to conventional Michelson interferometer-based laser vibrometers, the photo-EMF pulsed laser vibrometer (PPLV) does not require the use of retroreflective tapes or special electronic filtering to retrieve vividly the biological subject's life signs. Experimental results demonstrating the detection of life signs from various parts of biological subjects' bodies, with or without the coverage of clothing are presented. We also demonstrate the monitoring of a human subject's heart movements by interrogating the back of his/her hand. Results from using PPLV to determine extremity blood circulation at various levels of proximal occluding pressures are also presented.