In this work a laboratory guidance system has been constructed by computerized controller to track target, which is pointed to circular spot of the visible range of electromagnetic spectrum of He-Ne laser with λ = 6328.4°. The guidance process depends on processing the signals providing by a quadrant detector, which represents the sensing element of the homing guidance system. This work is divided into two parts, hardware and software. The hardware system consists of, quadrant detector, pre-amplifier and arithmetic circuit (used to amplify the four output of the quadrant detector linearly from (0-0.5 V) to (0-5 V) also solves the error equations in azimuth and elevation) analog to digital conversion circuit which convert the four amplifier error signals to 8-bit digital signals for each quadrant with a resolution equal to (0.01 V) per level, microprocessing unit which represent the controller and actuator to give the suitable command to track the laser target, digital driving circuit to drive the motors. Also the appropriate software is constructed to implement the digital PID controller and window generation. A complete setup is designed and many expirements are done to insure and verify the proposed approach. The results obtained show satisfactory values with the following accuracy. Azimuth error signal sensitivity is (1.67) V/rad. Elevation error signal sensitivity is (1.65) V/rad.