Patent ID: 7512163

Claim:
Apparatus for utilizing laser light in a controlled manner, comprising; a current source circuit configured to regulate a current to a first level; a current sink circuit configured to regulate the current to a second level; a laser diode electrically coupled in series between the current source circuit and the current sink circuit, and configured to have the current pass through the laser diode at a lower one of the current being driven by the current source circuit at the first level or the current being driven by the current sink circuit at the second level, wherein the current source circuit and the current sink circuit are configured to each independently maintain the laser diode within a desired predetermined operating tolerance despite the failure of either the current source circuit and the current sink circuit, and wherein the predetermined operating tolerance comprises a range of plus or minus five percent about the current at the first level or about the current at the second level; a sensor configured to detect light at a same frequency as light generated by the laser diode, and to generate a first signal in response to detecting the light; and a controller configured to repeatedly and sequentially enable, and then disable, the current source circuit and the current sink circuit, such that the current is repeatedly and sequentially increased and decreased.