Method and apparatus for using a photoacoustic effect for controlling various processes utilizing laser and ion beams, and the like

Claim 1

A novel method for controlling various processes by utilizing a photoacoustic effect principle, whether or not the various processes are with regard to a solid or non-solid fluid medium, said processes using and requiring control of a primary excitation beam of the type including laser beams, microwave beams, x-rays and other electromagnetic wave beams, as well as ion, electron, particle and molecular beams, and which processes include the use of appropriate beam-generating means and beam-generating power control means in conjunction therewith, said novel method comprising the steps of: (a) generating and modulating in a pulsing manner a selected type of primary excitation beam; (b) directing said beam at a workpiece or work area to be treated thereby, so as to create a temperature variation thereat, and so as to establish a photoacoustic effect; (c) continuously monitoring the beam-impacted work area by one of several different photoacoustic effect detection techniques which includes means for detecting the characteristic temperature variation in said area, which variation can manifest itself as pressure, index of refraction, thermoelastic, or infrared (IR) radiation changes, considered singly and in various combinations; (d) said monitoring step resulting in generating an electrical signal by appropriate transducer means, with the signal to be used by ancillary signal processing means; (e) said monitoring further using the selected type photoacoustic effect detecting means for detecting any such work area temperature variation outside of a predetermined acceptable - unacceptable temperature range which is indicative that the given process with which this control procedure or process is being used is in need of correction, and (f) using said electrical signal as generated in conjunction with said monitoring means of sub-paragraphs (c) (d) (e), together with ancillary signal-processing control circuit means for effectively maintaining and modifying as needed the beam-generating power control to assure proper overall processing.

Claim 26

A method for optimizing uniformity of treatment of the surface of a solid work piece having non-uniform optical and thermal absorption properties on or near the surface with a variable intensity primary excitation beam, said method utilizing a photoacoustic effect principal, a power control, and a photoacoustic effect detector; said beam intensity being controlled by said power control; said method being primarily directed to maintain optimum beam intensity on the surface being treated by varying said beam intensity as a function of the physical properties of a treatment area; said method comprising the steps of: a. imaging said beam on said treatment area to raise the temperature of the surface; b. modulating said beam in a pulsing manner to induce a photoacoustic effect having a magnitude and phase at said treatment area; c. detecting said photoacoustic effect produced by said pulsing beam with said photoacoustic detector means; said detector means generating an electrical signal output corresponding to said magnitude and phase of said photoacoustic effect, which output is proportional to the temperature at the treatment surface; d. processing said output to conform the signal to a condition acceptable by said power control; e. directing said output to feedback to said power control; f. adjusting the power control in response to the feedback, thereby varying said beam intensity to maintain said optimum beam intensity on said treatment area; whereby said work piece receives a substantially uniform treatment relatively independent of non-uniform optical and thermal absorption properties on or near the work piece surface.

Claim 27

A method for optimizing uniformity of treatment of the surface of a solid work piece having non-uniform optical and thermal absorption properties on or near the surface with a variable intensity primary excitation beam, said method utilizing a photoacoustic effect principal, a power control, and a photoacoustic effect detector; said beam intensity being controlled by said power control; said method being primarily directed to maintain optimum beam intensity on the surface being treated by varying said beam intensity as a function of the physical properties of a treatment area; said method comprising the steps of: a. imaging said beam on said treatment area to raise the temperature of the surface; b. modulating said beam in a pulsing manner to induce a photoacoustic effect having a magnitude and phase at said treatment area; c. detecting said photoacoustic effect produced by said pulsing beam with said photoacoustic detector means; said detector means generating an electrical signal output corresponding to said magnitude and phase of said photoacoustic effect, which output is proportional to the temperature at the treatment surface; d. processing said output to conform the signal to a condition acceptable by said power control; e. directing said output to feedback to said power control; f. adjusting the power control in response to the feedback, thereby varying said beam intensity to maintain said optimum beam intensity on said treatment area; whereby said work piece receives a substantially uniform treatment relatively independent of non-uniform optical and thermal absorption properties on or near the work piece surface.