ALIGNMENT APPARATUS FOR PHOTOELECTRIC INTRUSION DETECTOR SYSTEM

An alignment apparatus for a photoelectric transmitter or receiver having an emitter or detector at the focal point of a focusing lens or mirror includes a plane mirror located between the emitter or detector and the focusing device. The mirror is provided with an aperture behind which the emitter or detector is located. A center line indicating sight is provided between the focusing device and the emitter or detector. By observing the plane mirror from an appropriate angle the transmitter or receiver can be aligned with its counterpart transmitter or receiver.