This project studies and simulates the infrared detection system to measure the incident angles of a laser beam in space, and tracking this beam depends on multi detectors. This system includes the following units; 1- Detection units. 2-Interface circuit. 3- Quantizer circuit. 4- Display unit. The detection unit consists of lens, optical filter, thermal detector and preamplifier. Eight detection units will be used to make coverage for 360o. The interface circuit consists of buffers, adders and amplifiers. The quantizer circuit consists of comparators circuit, tangent rule circuit, encoder and octant sensor and counter digital display. The last unit displays the angle of arrival depending on the input signals and the relative amplitude of each detector. The system is studied to detect a 2.7μm laser beam because of the weaponry has this wavelength value. Field of view of each detector is greater than or equal 60°. However; the number of the detectors in the system is eight. By using software programs the detector beam coverage and also the relative amplitude of the main direction detector will be obtained.