The apparatus includes a diode laser and a current source interconnected with the diode laser. Two independent circuits in the current source are configured to limit current flowing through the diode laser. A first current limiter circuit configured to limit a current output from the current source to an anode of the diode laser, and an independent second current limiter circuit configured to limit a current return from a cathode of the diode laser to the current source so that laser output power does not exceed a specified maximum regardless of a single fault in either the first or second current limiter circuits.