Abstract: An apparatus is provided that includes a near infrared (NIR) light emitting diode (LED) having a predominant axis of NIR light transmission from the NIR LED and a lens that disperses NIR light received from the NIR LED with respect to first and second planes, the lens having an air to lens light entry boundary where light from the NIR LED enters a surface of the lens and a lens to air boundary where the light exits the lens in each of the first and second planes, wherein an intersection formed by the second plane with the surface is a line that is concave on each side of the predominant axis, and wherein a radius of the air to lens light entry boundary of the line successively increases over each span of a predetermined number of degrees progressing outwards along the line from the predominant axis.

Abstract: A tamper resistant motion detector is provided that can include a housing, a capacitive sensor, and a microprocessor. The housing can include a window, and the capacitive sensor can be located inside of the housing, behind the window. A capacitance of the capacitive sensor can change when the capacitive sensor detects an object on the window or within a predetermined distance from the window, and the microprocessor can read the capacitance of the capacitive sensor and use the capacitance of the capacitive sensor to determine whether to activate an alarm or to determine whether to activate an anti-mask system.

Abstract: An apparatus including a near infrared (NIR) light emitting diode (LED) having a predominant axis of NIR light transmission from the LED and a lens that disperses NIR light received from the LED with respect to first and second planes, the lens having an air to lens light entry boundary where light from the LED enters a surface of the lens and a lens to air boundary where light exits the lens in each of the first and second planes, the intersection forming by the second plane with the light entry surface is a line that is concave on each side of the predominant axis and where a radius of the light entry boundary of the line successively increase over each span of a predetermined number of degrees progressing outwards along the line from the predominant axis.

Abstract: A tamper resistant motion detector is provided that can include a housing, a capacitive sensor, and a microprocessor. The housing can include a window, and the capacitive sensor can be located inside of the housing, behind the window. A capacitance of the capacitive sensor can change when the capacitive sensor detects an object on the window or within a predetermined distance from the window, and the microprocessor can read the capacitance of the capacitive sensor and use the capacitance of the capacitive sensor to determine whether to activate an alarm or to determine whether to activate an anti-mask system.