The 3664 Optical Power Meter serves the dual purposes of not only as a convenient tool for the R&D and field maintenance of devices that incorporate laser light sources, but also as the primary instrument for measuring the quality of the optical pickup that is the core of today's high tech equipment such as DVD recorders, CD drives, copiers, laser printers, etc., during their production. The built-in compensation feature, indispensable for manufacturing applications, allows you to set the standard value based on a measured value at the touch of a button, and equate the value to all subsequent measurements falling within the accuracy range.