Abstract: A device is presented for computing an optical center of a sensor array relative to a lens. The sensor array includes a plurality of sensor units, and each sensor unit has a position on the sensor array. The lens defines an optical axis. The device includes a configuration module and a processing circuit. The configuration module is provided for positioning the lens and the sensor array thereon. When test light is parallel to the optical axis and is incident to the lens, the sensor array receives the test light transmitted by the lens so that each sensor unit outputs a value. The processing circuit is linked to the sensor array for receiving values outputted from the sensor units and selecting positions of sensor units outputting a specific value among the values, for computing the optical center of the sensor array.