Process monitor for laser and plasma materials processing of materials

Abstract

A method for monitoring the processing of a workpiece includes directing an incident laser beam onto the workpiece and measuring a signal emitted from the workpiece. At least two signals are generated by a detector based upon the emitted signal. A workpiece processing quality is determined based upon the ratio of the two output signals and a magnitude of one of the two outputs.

1 - 13 . (canceled)  
   
   
       14 . An apparatus for processing and monitoring a workpiece, the apparatus comprising: 
 a light source that directs an incident laser beam onto a workpiece;    an optical detector for measuring at least one signal emitted from said workpiece in response to the incident laser beam, said optical detector generating two outputs based on said at least one signal; and    a light source monitor in communication with said optical detector, wherein said light source monitor determines whether a condition of the processing, of the workpiece is an overcombustion cutting condition or a non-penetrating cutting condition based upon a ratio of said two outputs and a magnitude of at least one of said two outputs.    
   
   
       15 . The apparatus of  claim 14  wherein said detector comprises a sandwich detector.  
   
   
       16 . The apparatus of  claim 14  wherein said detector comprises two elements.  
   
   
       17 . The apparatus of  claim 14  wherein the light source monitor determines the condition of the processing of the workpiece by: 
 determining a location in a lookup table based on said ratio and said magnitude of at least one of said two outputs; and    extracting a value from said lookup table based upon said location in said lookup table.    
   
   
       18 . The apparatus of  claim 14  wherein the apparatus determines a value for said two outputs and said magnitude of at least one of said two outputs indicative of a good cut by cutting a test workpiece.  
   
   
       19 . The apparatus of  claim 14  wherein said magnitude of the at least one of said two outputs is a maximum value.  
   
   
       20 . The apparatus of  claim 14  wherein said detector comprises at least two detector elements.  
   
   
       21 . The apparatus of  claim 14  wherein said two outputs comprise a first spectral band of light and a second spectral band of light.  
   
   
       22 . The apparatus of  claim 21  wherein said first spectral band of light has a lower band of wavelengths than the second spectral band of light.  
   
   
       23 . The apparatus of  claim 21  wherein said first spectral band of light is a spectral band between about 450 nm and about 650 nm.  
   
   
       24 . The apparatus of  claim 21  wherein said second spectral band of light is a spectral band between about 950 nm and about 1150 nm.  
   
   
       25 . The apparatus of  claim 14  wherein said light source comprises a cutting head, said cutting head comprises a plenum, a nozzle, a focusing lens, and an optical receiver.  
   
   
       26 . The apparatus of  claim 14  wherein said apparatus further comprises an optical receiver in communication with said detector for receiving said at least one signal.  
   
   
       27 . The apparatus of  claim 26  wherein said optical receiver comprises at least one port for conveying said at least one signal to a cable, said cable for conveying said at least one signal to said detector.  
   
   
       28 - 29 . (canceled)