The present invention is directed to a replaceable lamp assembly for a point-of-use water treatment system. In the program, in the case where a converter is performing an operation for increasing a voltage, when a difference between an estimated battery voltage VBE and a battery voltage VB has continued to be large, the ECU tentatively determines that a battery voltage sensor is abnormal, and stops voltage increasing control for the converter. A scanner transversely scans the target with the object beam over a plurality of image points defined by the resolution of the apparatus. A linear combination of filters is applied to a detection window in the set of combined images to determine motion and appearance features of the detection window.