Embodiments of the present invention generally relate to circuits, systems and methods that can be used to detect light beam misalignment, so that compensation for such misalignment can be performed. In accordance with an embodiment, a circuit includes a photo-detector (PD) having a plurality of electrically isolated PD segments. Additionally, the circuit has circuitry, including switches, configured to control how currents indicative of light detected by the plurality of electrically isolated PD segments are arithmetically combined. When the switches are in a first configuration, a signal produced by the circuitry is indicative of vertical light beam alignment. When the switches are in a second configuration, the signal produced by the circuitry is indicative of horizontal light beam alignment. The signals indicative of vertical light beam alignment and horizontal light beam alignment can be used detect light beam misalignment, so that compensation for such misalignment can be performed.