Systems and methods for measuring radiated thermal energy during an additive manufacturing operation

Abstract

This disclosure describes various methods and apparatus for characterizing an additive manufacturing process. A method for characterizing the additive manufacturing process can include generating scans of an energy source across a build plane; measuring an amount of energy radiated from the build plane during each of the scans using an optical sensing system that monitors two discrete wavelengths associated with a blackbody radiation curve of the layer of powder; determining temperature variations for an area of the build plane traversed by the scans based upon a ratio of sensor readings taken at the two discrete wavelengths; determining that the temperature variations are outside a threshold range of values; and thereafter, adjusting subsequent scans of the energy source across or proximate the area of the build plane.

1 . (canceled) 
     
     
         2 . An additive manufacturing method, comprising:
 identifying at least one spectral peak associated with material properties of a powder;   selecting at least a first wavelength offset from the at least one identified spectral peak;   scanning an energy source across at least a portion of a layer of the powder;   measuring, at the first wavelength, energy radiated from the at least a portion of the layer of the powder; and   determining a temperature of the at least a portion of the layer of the powder based at least in part on the measured energy.   
     
     
         2 . The additive manufacturing method of  claim 2  wherein the selecting at least a first wavelength comprises selecting a first wavelength and a second wavelength that are each offset from the at least one spectral peak. 
     
     
         3 . The additive manufacturing method of  claim 2  further comprising measuring, at the second wavelength, energy radiated from the at least a portion of the layer of the powder. 
     
     
         4 . The additive manufacturing method of  claim 3  further comprising determining a temperature of the at least a portion of the layer of powder based upon a ratio of energy radiated at the first wavelength to energy radiated at the second wavelength. 
     
     
         5 . The additive manufacturing method of  claim 3  further comprising determining variations in temperature of the at least a portion of the layer of powder based upon a ratio of energy radiated at the first wavelength to energy radiated at the second wavelength. 
     
     
         6 . The additive manufacturing method of  claim 5  further comprising determining that the variations in temperature are outside a threshold range of values. 
     
     
         7 . The additive manufacturing method of  claim 1  further comprising determining an area of the at least a portion of a layer of the powder by:
 determining a start point of a first scan of the energy source; 
 determining an end point of the first scan; and 
 determining a length of the first scan by calculating a distance between the start point and the end point. 
 
     
     
         8 . The additive manufacturing method of  claim 7  further comprising: mapping a thermal energy density to locations within a part being formed by the additive manufacturing method by:
 receiving energy source drive signal data indicating a path of the energy source across the at least a portion of a layer of the powder; and 
 determining a location of the scanning using the energy source drive signal data. 
 
     
     
         9 . An additive manufacturing system, the system comprising:
 an energy source configured to direct a beam of energy at a build plane that includes a layer of powder;   a sensor that identifies at least one spectral peak associated with material properties of the powder;   a detector that measures an amount of energy radiated from the build plane when the energy source is scanned across a region of the build plane, wherein the detector measures the energy at a wavelength that is offset from the identified at least one spectral peak; and   a processor configured to receive data from the detector and to determine a temperature of the region of the build plane.   
     
     
         10 . The additive manufacturing system of  claim 9  wherein the detector is a first detector that measures the energy at a first wavelength, the system further comprising a second detector that measures the energy at a second wavelength wherein the second wavelength is offset from the a least one spectral peak. 
     
     
         11 . The additive manufacturing system of  claim 10  wherein the processor is configured to receive data from the first and the second detector and to determine a temperature of the region of the build plane based upon a ratio of energy radiated at the first wavelength to energy radiated at the second wavelength. 
     
     
         12 . The additive manufacturing system of  claim 10  wherein the processor is configured to determine variations in temperature of the region of the build plane based upon a ratio of energy radiated at the first wavelength to energy radiated at the second wavelength. 
     
     
         13 . The additive manufacturing system of  claim 13  wherein the processor is configured to determine if the variations in temperature are outside a threshold range of values. 
     
     
         14 . The additive manufacturing system of  claim 14  wherein the processor is configured to generate an alert in response to the variations in temperature being outside the threshold range of values. 
     
     
         15 . The additive manufacturing system of  claim 9  further comprising determining an area of the region of the build plane by:
 determining a start point of a first scan of the energy source; 
 determining an end point of the first scan; and 
 determining a length of the first scan by calculating a distance between the start point and the end point. 
 
     
     
         16 . The additive manufacturing system of  claim 16  further comprising: mapping a thermal energy density to locations within a part being formed by the additive manufacturing system by:
 receiving energy source drive signal data indicating a path of the energy source across the region of the build plane; and 
 determining a location of the scanning using the energy source drive signal data. 
 
     
     
         17 . A method of operating an additive manufacturing system, the method comprising:
 scanning a laser beam across a region of a build plane, wherein the build plane comprises a layer of powder configured to be fused by the laser beam and the powder has at least one spectral peak associated with material properties of the powder;   measuring, at a first wavelength, energy radiated from the region of the build plane during the scanning, wherein the first wavelength is offset from the at least one spectral peak of the powder;   determining a temperature of the region of the build plane during the scanning based at least in part on the measured energy.   
     
     
         18 . The method of  claim 17  wherein the at least one spectral peak is based on material properties of the powder when the powder is undergoing laser irradiation. 
     
     
         19 . The method of  claim 17  wherein the at least one spectral peak and the first wavelength are determined with a spectrometer. 
     
     
         20 . The method of  claim 17  further comprising measuring, at a second wavelength, energy radiated from the region of the build plane during the scanning, wherein the second wavelength is offset from the at least one spectral peak of the powder. 
     
     
         21 . The method of  claim 20  further comprising determining a temperature of the region based upon a ratio of energy radiated at the first wavelength to energy radiated at the second wavelength.