A method for detecting reflectors within a field of vision, comprising: providing a sensor body having an electromagnetic transceiver (1, 4) for sending and receiving an electromagnetic signal, said sensor body further having a comparator, a timer and an alarm signal; said transceiver sending an electromagnetic signal downrange to an area of interest; said transceiver receiving a reflected signal comprising in part the sent electromagnetic signal; said timer determining the signal elapsed time between the transceiver sending the signal downrange and receiving the reflected signal back at the transceiver, wherein the transceiver sending the signal is defined as the start time; said sensor comparator comparing the intensity of the reflected signal against a generated expected signal intensity to determine whether the reflected signal is above a threshold signal strength for the determined signal elapsed time according to a threshold signal strength versus signal elapsed time curve, wherein the threshold signal strength in the curve decreases with the signal elapsed time; said sensor comparator triggering the alarm signal when said reflected signal is greater than said retrieved expected signal intensity, wherein said alarm signal is one of the group of an audible signal, a visual signal, movement of a mechanical device or a vibratory signal to signal the presence of one of a highly reflective surface, a reflector or a retro-reflector within the field of scope of the sensor; and said sensor comparator turning off the alarm signal when said reflected signal is less than said retrieved expected signal intensity, wherein said alarm signal is one of the group of an audible signal, a visual signal, movement of a mechanical device or a vibratory signal to signal the absence of any highly reflective surface, reflector and retroreflector within the field of scope of the sensor. providing a sensor body having an electromagnetic transceiver (1, 4) for sending and receiving an electromagnetic signal, said sensor body further having a comparator, a timer and an alarm signal; said transceiver sending an electromagnetic signal downrange to an area of interest; said transceiver receiving a reflected signal comprising in part the sent electromagnetic signal; said timer determining the signal elapsed time between the transceiver sending the signal downrange and receiving the reflected signal back at the transceiver, wherein the transceiver sending the signal is defined as the start time; said sensor comparator comparing the intensity of the reflected signal against a generated expected signal intensity to determine whether the reflected signal is above a threshold signal strength for the determined signal elapsed time according to a threshold signal strength versus signal elapsed time curve, wherein the threshold signal strength in the curve decreases with the signal elapsed time; said sensor comparator triggering the alarm signal when said reflected signal is greater than said retrieved expected signal intensity, wherein said alarm signal is one of the group of an audible signal, a visual signal, movement of a mechanical device or a vibratory signal to signal the presence of one of a highly reflective surface, a reflector or a retro-reflector within the field of scope of the sensor; and said sensor comparator turning off the alarm signal when said reflected signal is less than said retrieved expected signal intensity, wherein said alarm signal is one of the group of an audible signal, a visual signal, movement of a mechanical device or a vibratory signal to signal the absence of any highly reflective surface, reflector and retroreflector within the field of scope of the sensor.