Browse Prior Art Database

Original Publication Date: 1981-Feb-28
Included in the Prior Art Database: 2004-Apr-02

Publishing Venue

Xerox Disclosure Journal


A portable device is provided to measure the actual power and noise of a laser/illuminator beam to a reasonable degree of accuracy. The device, as shown in the figure, comprises a detector head (not shown) which contains a neutral density filter, a silicon photo detector (which converts the beam illumination to a current signal whose magnitude is proportional to the laser beam intensity), and a suitable connector (e.g., coaxial cable) connected to electronics module 10 at Jl. The electronics module 10 consists of a current-to-voltage converter/amplif ier U 1 and U2 which feeds both the converted current signal to a DC filter/amplifier U3 (the noise filter comprising resistor R10 and capacitor C3 removes the AC component of the signal) and a peak-to-peak noise detector comprising amplifiers U5 and U6 (capacitor C8 allows only the AC component of the signal to pass to the detector). The DC output of the detector is adjusted by potentiometer 12 and buffered by U7. Potentiometer 12 provides calibration to an equivalent RMS noise, DC level. This RMS DC level and the DC output of U3 are fed to a divider U4. The