A multi-stage control for an auto-darkening lens includes a first detector to detect initiation of welding and a second detector to detect continuation of welding after welding has been initiated. The first detector has relatively low sensitivity and fast response time; and the second detector has relatively high sensitivity that can be altered as may be necessary, relatively slow response time to allow opportunity to determine whether welding is continuing as inputs indicative of welding, and adaptive filtering to filter ambient effects and the like from such inputs to avoid false detection of welding. A method of enhancing operation of an auto-darkening lens control that has a detector and associated circuitry to detect initiation of welding substantially independently of time based filtering and to maintain detecting of welding using time based discrimination, comprising coupling control signals and power to an auto-darkening lens via a substantially unimpeded path from a detector to the auto-darkening lens.

 
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> P-type group II-VI semiconductor compounds

~ 00315