Meet the EOTech X320 Handheld Thermal Imager: a lightweight, handheld thermal camera ideal for day or nighttime activity. It offers 320×240 resolution and white hot, black hot, and 3 color modes. You will be able to use this to detect human activity up to 800 yards away. The push-button rotary switch lets you use your thermal imager easily. The device is available in 30 Hz or 9 Hz. You also get up to 4x zoom and a video port for recording.
The battery life lasts for 6 hours ( 2 x AA). The device is shockproof and has a FoV of 12° x 9°. Not cheap though.