In this paper we are interested in modeling, performance evaluation, and measurement of a quadrant detector. Photodiode is modeled using its differential equations then implemented and solved using ORCAD-pspise. The model validation was performed by comparing the model results with the experimental measurements using a proposed setup. The model was used to investigate the effect of the photodiode donor concentrations, acceptor concentrations and intrinsic region concentrations. The simulation results showed that the donor concentrations should be kept as small as possible in order to improve the photodiode performance, the acceptor concentrations has a small effect on the performance, and as the intrinsic region concentration increases the photocurrent increases and the junction capacitance decreases with a small increase in the dark current.

In this paper we are interested in modeling, simulation, and measurement of laser spot position determination circuit (LSPDC) with a quadrant detector (QD). Photodiode is modeled using its differential equations then implemented using ORCAD-pspise. Starting with the output of the detector, the circuit modeling and simulation for the preamplifier, post amplifier, ADC and microcontroller card were performed. PCB card implementation was performed and integrated with the QD and the necessary optical system components. The implementation of the full LSPDC with the detector is performed. General system for testing the spot LSPDC was performed with a laser source simulating the incident radiation and a mechanical system to enable adjusting different angles. Good agreement was achieved between the measured data and the adjusted angles with a small error attributed to the error in the adjusted mechanical system and the stability of the used laser source.