Portable laser induced breakdown spectroscopy systems

Abstract

An embodiment of a laser induced breakdown system is described that comprises a portable device that includes: a laser configured to produce a beam comprising a plurality of repeating pulses; a processor configured to open a data acquisition window after a delay period, wherein the delay period begins upon production of one of the pulses; one or more optical elements configured to direct the beam at a sample and collect emitted light from a plasma continuum; and an optical detector configured to produce a plurality of signal values from the emitted light from the plasma continuum collected during the data acquisition window, wherein the processor is configured to identify an element from the signal values.

What is claimed is: 
     
         1 . A laser induced breakdown system, comprising:
 a portable device that comprises:
 a laser configured to produce a beam comprising a plurality of repeating pulses; 
 a detector that detects a time point of an actual pulse from the laser; 
 a processor configured to open a data acquisition window after a delay period, wherein the delay period begins at the time point of the actual pulse; 
 one or more optical elements configured to direct the beam at a sample and collect emitted light from a plasma continuum; and 
 a second optical detector configured to produce a plurality of signal values from the emitted light from the plasma continuum collected during the data acquisition window, wherein the processor is configured to identify an element from the signal values. 
   
     
     
         2 .- 3 . (canceled) 
     
     
         4 . The laser induced breakdown system of  claim 1 , further comprising:
 a temperature detector that acquires a temperature measurement.   
     
     
         5 . The laser induced breakdown system of  claim 4 , wherein:
 the temperature detector is positioned inside a housing of the portable device.   
     
     
         6 . The laser induced breakdown system of  claim 4 , wherein:
 the temperature measurement is acquired at substantially the same time as when the laser produces the beam.   
     
     
         7 . The laser induced breakdown system of  claim 6 , wherein:
 the processor uses the temperature measurement to compensate for a temperature related difference in a calibration curve.   
     
     
         8 . The laser induced breakdown system of  claim 7 , wherein:
 the temperature related difference in a calibration curve comprises a difference in a slope of the calibration curve.   
     
     
         9 . The laser induced breakdown system of  claim 7 , wherein:
 the processor compensates for a temperature related difference using a change in the delay period.   
     
     
         10 . The laser induced breakdown system of  claim 1 , wherein:
 the processor is configured to open a second data acquisition window after a second delay period.   
     
     
         11 . The laser induced breakdown system of  claim 10 , wherein:
 the first data acquisition window and the second data acquisition window comprise different durations of time.   
     
     
         12 . The laser induced breakdown system of  claim 10 , wherein:
 the first data acquisition window and the second data acquisition window comprise overlapping durations of time.   
     
     
         13 . The laser induced breakdown system of  claim 10 , wherein:
 the processor obtains the plurality of signal values using the first delay period and a plurality of signal values using the second delay period; and   the processor calculates a differential value between one or more of the signal values from the first delay period and the corresponding signal values from the second delay period.   
     
     
         14 . The laser induced breakdown system of  claim 13 , wherein:
 the processor selects one of the first or second delay periods based on the differential value.   
     
     
         15 . The laser induced breakdown system of  claim 1 , wherein:
 the data acquisition window does not comprise a duration substantially greater than the delay period.   
     
     
         16 . The laser induced breakdown system of  claim 1 , further comprising:
 a variable filter element that modifies a power level of the beam.   
     
     
         17 . The laser induced breakdown system of  claim 16 , further comprising:
 a temperature detector that detects ambient temperature, wherein the processor modifies the relative position of the variable filter with the beam using the ambient temperature.   
     
     
         18 . A method, comprising:
 identifying an element using a portable device that performs a method comprising:
 producing a beam from a laser comprising a plurality of repeating pulses; 
 detecting a time point of an actual pulse from the laser; 
 directing the beam at a sample; 
 collecting emitted light in response to the beam; 
 opening a data acquisition window after a delay period, wherein the delay period begins at the time point of the actual pulse; 
 producing a plurality of signal values from the emitted light collected during the data acquisition window; and 
 identifying the element from the signal values. 
   
     
     
         19 .- 20 . (canceled) 
     
     
         21 . The method of  claim 18 , wherein the method performed by the portable device further comprises:
 acquiring a temperature measurement.   
     
     
         22 . The method of  claim 21 , wherein:
 the temperature measurement is acquired from inside a housing of the portable device.   
     
     
         23 . The method of  claim 21 , wherein:
 the temperature measurement is acquired at substantially the same time as when the laser produces the beam.   
     
     
         24 . The method of  claim 21 , wherein the method performed by the portable device further comprises:
 compensating for a temperature related difference in a calibration curve using the temperature measurement.   
     
     
         25 . The method of  claim 24 , wherein:
 the temperature related difference in a calibration curve comprises a difference in a slope of the calibration curve.   
     
     
         26 . The method of  claim 24 , wherein:
 the processor compensates for a temperature related difference using a change in the delay period.   
     
     
         27 . The method of  claim 18 , wherein the method performed by the portable device further comprises:
 opening a second data acquisition window after a second delay period.   
     
     
         28 . The method of  claim 27 , wherein:
 the first data acquisition window and the second data acquisition window comprise different durations.   
     
     
         29 . The method of  claim 27 , wherein:
 the first data acquisition window and the second data acquisition window comprise overlapping durations.   
     
     
         30 . The laser induced breakdown system of  claim 27 , wherein the method performed by the portable device further comprises:
 obtaining the plurality of signal values using the first delay period and a plurality of signal values using the second delay period; and   calculating a differential value between one or more of the signal values from the first delay period and the corresponding signal values from the second delay period.   
     
     
         31 . The method of  claim 30 , wherein the method performed by the portable device further comprises:
 selecting one of the first or second delay periods based on the differential value.   
     
     
         32 . The method of  claim 18 , wherein:
 the data acquisition window does not comprise a duration substantially greater than the delay period.   
     
     
         33 . The method of  claim 18 , wherein the method performed by the portable device further comprises:
 modifying a power level of the beam using a variable filter element.   
     
     
         34 . The method of  claim 33 , wherein the method performed by the portable device further comprises:
 acquiring a temperature measurement; and   modifying a relative position of the variable filter element with the beam using the temperature measurement.   
     
     
         35 . The laser induced breakdown system of  claim 1 , wherein:
 the time point of an actual pulse from the laser occurs later than a time point of an expected pulse from the laser.   
     
     
         36 . The laser induced breakdown system of  claim 1 , wherein:
 the detector comprises an optical detector.   
     
     
         37 . The laser induced breakdown system of  claim 1 , wherein:
 the optical detector comprises a fast photo diode.   
     
     
         38 . The method of  claim 18 , wherein:
 the time point of an actual pulse from the laser occurs later than a time point of an expected pulse from the laser.