Recommended mounting height for SAFR SCAN is 46 to 58 inches (115 to 150 cm).  The image below shows SAFR SCAN mounted at 55 inches (1.4 meters).  The upper and lower bounding lines show the vertical range of the IR sensors. While the visible spectrum (camera) range is greater, the limiting factor for anti-spoofing is with the IR sensor range.  

With a person at a distance of 3 feet (.9 meters), the operating range is from 2 feet 2 inches to 6 feet 11 inches.

Note: Optimal performance (fastest verification) occurs in the range of -20° to 20°.  Outside of this range, SAFR SCAN will work but be slower to authenticate when anti-spoofing is enabled.