METHODS AND SYSTEMS FOR COHERENT IMAGING AND FEEDBACK CONTROL FOR MODIFICATION OF MATERIALS

• US 20120138586A1
• Filed: 09/26/2011
• Published: 06/07/2012
• Est. Priority Date: 09/25/2010
• Status: Active Grant

• Current Assignee: IPG Photonics Corporation
• Original Assignee: Queen's University At Kingston
• Inventors: WEBSTER, Paul J. L., FRASER, James M., YANG, Victor X. D.
• Granted Patent: US 8,822,875 B2
• Time in Patent Office: Days
• US Class Current: 219/121.64
• CPC Class Codes: A61B 18/20 using laser
• CPC Class Codes: A61B 2017/00057 Light
• CPC Class Codes: A61B 2018/00642 with feedback, i.e. closed loop control
• CPC Class Codes: B22F 10/10 Formation of a green body
• CPC Class Codes: B22F 10/30 Process control
• CPC Class Codes: B22F 10/322 of the gas flow, e.g. rate or direction
• CPC Class Codes: B22F 10/36 of energy beam parameters
• CPC Class Codes: B22F 10/366 Scanning parameters, e.g. hatch distance or scanning strategy
• CPC Class Codes: B22F 10/64 by thermal means control of energy beam parameters for post heating B22F10/364
• CPC Class Codes: B22F 10/66 by mechanical means
• CPC Class Codes: B22F 12/41 characterised by the type, e.g. laser or electron beam
• CPC Class Codes: B23K 15/0013 Positioning or observing workpieces, e.g. with respect to the impact; Aligning, aiming or focusing electronbeams
• CPC Class Codes: B23K 15/02 Control circuits therefor
• CPC Class Codes: B23K 15/08 Removing material, e.g. by cutting, by hole drilling
• CPC Class Codes: B23K 15/085 Boring
• CPC Class Codes: B23K 2103/42 Plastics B23K2103/16 takes precedence
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 26/03 Observing, e.g. monitoring, the workpiece
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/20 Bonding soldering by means of radiant energy B23K1/005; joining of preformed plastics parts by heating using laser beam B29C65/16
• CPC Class Codes: B23K 26/348 : in combination with arc heating, e.g. TIG [tungsten inert gas], MIG [metal inert gas] or plasma welding laser beam for starting a welding or cutting arc B23K9/067
• CPC Class Codes: B23K 26/361 : for deburring or mechanical trimming B23K26/351 takes precedence
• CPC Class Codes: B23K 26/362 : Laser etching
• CPC Class Codes: B23K 26/382 : by boring
• CPC Class Codes: B23K 9/0956 : using sensing means, e.g. optical
• CPC Class Codes: B29C 64/153 : using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• CPC Class Codes: B29C 64/393 : for controlling or regulating additive manufacturing processes
• CPC Class Codes: B33Y 30/00 : Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: C21D 10/00 : Modifying the physical properties by methods other than heat treatment or deformation
• CPC Class Codes: C22F 3/00 : Changing the physical structure of non-ferrous metals or alloys by special physical methods, e.g. treatment with neutrons
• CPC Class Codes: G01B 11/22 : for measuring depth
• CPC Class Codes: G01B 9/0203 : With imaging systems
• CPC Class Codes: G01J 3/453 : by correlation of the amplitudes
• CPC Class Codes: G01N 2021/8416 : and process controlling, not otherwise provided for
• CPC Class Codes: G01N 21/84 : Systems specially adapted for particular applications
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

Methods and systems are provided for using optical interferometry in the context of material modification processes such as surgical laser or welding applications. An imaging optical source that produces imaging light. A feedback controller controls at least one processing parameter of the material modification process based on an interferometry output generated using the imaging light. A method of processing interferograms is provided based on homodyne filtering. A method of generating a record of a material modification process using an interferometry output is provided.

Claims

1-45. -45. (canceled)

46. An apparatus that generates a record of a material modification process, the apparatus comprising:

a material processing beam source that produces a material processing beam that is applied to a sample location in the material modification process, wherein the material modification process is a welding process;

an imaging optical source that produces imaging light;

an optical interferometer that produces an interferometry output using at least a component of the imaging light that is delivered to the sample, the interferometry output based on at least one optical path length to the sample compared to another optical path length; and

a record generator that generates a record of the material modification process based on the interferometry output at a plurality of times.

47. The apparatus of claim 46 further comprising:

a computer readable storage medium;

wherein the record generator stores the record on the computer readable storage medium.

48. The apparatus of claim 46 wherein apparatus is configured to produce the material processing beam and the imaging light substantially co-axially when delivered to the sample.

49-97. -97. (canceled)

98. A method of generating a record of a material modification process, the method comprising:

applying a material processing beam to a sample location as part of the material modification process, wherein the material modification process is a welding process;

generating imaging light with an imaging optical source;

producing an interferometry output using at least a component of the imaging light that is delivered to the sample, the interferometry output based on at least one optical path length to the sample compared to another optical path length; and

generating at least one record of the material modification process based on the interferometry output at a plurality of times.

99. The method of claim 98 further comprising:

storing the at least one record.

100. The method of claim 98 wherein the material processing beam and the imaging light are substantially co-axial when delivered to the sample.

101. The method of claim 98 wherein the at least one record comprises a quality of the laser weld.

102. The method of claim 98 wherein the at least one record comprises an element of the melt pool in the process of laser welding.

103. The method of claim 98 wherein the at least one record comprises indications of an impending break through.

104. The method of claim 98 wherein a material interface on the interior of the sample is identified and used for controlling the material modification process.

105. The method of claim 98 wherein the at least one record comprises keyhole stability.

106. The method of claim 98 wherein the at least one record comprises penetration depth.

121. The method of claim 98 further comprising controlling at least one processing parameter of the material modification process based on the at least one record.

122. The method of claim 98 wherein the at least one record comprises at least two records.

123. The method of claim 122 further comprising controlling at least two processing parameters of the material modification process based on the at least two records.

124. The method of claim 121 wherein controlling at least one processing parameter of the material modification process based on the at least one record is performed in real-time to control the at least one processing parameter of the material modification process during said process.

125. The method of claim 121 wherein the at least one processing parameter of the material modification process that is controlled comprises at least one of:

on/off state of the material processing beam;

average power of the material processing beam;

pulse duration of the material processing beam;

peak intensity of the material processing beam;

density of the material processing beam;

energy of the material processing beam;

particle species of the material processing beam;

wavelength of the material processing beam;

pulse repetition rate of the material processing beam;

pulse energy of the material processing beam;

pulse shape of the material processing beam

scan speed of the material processing beam;

focal diameter of the material processing beam;

focal position of the material processing beam;

spatial pattern of the material processing beam on the sample;

material feed rate;

cooling media flow rate;

cover/assist gas flow rate;

cover/assist gas pressure;

cover/assist gas blend;

arc welding process parameters (such as voltage, current and wire feed rate); and

additive material feed rate.

126. The method of claim 98 further comprising:

automatically controlling at least one processing parameter of a material modification process based on the at least one record.

127. The method of claim 98 wherein applying a material processing beam comprises welding a metal, a plastic or a polymer.

128. The method of claim 98 wherein applying a material processing beam to the sample location in the material modification process comprising applying a material processing beam to at least one of:

metal;

semiconductor;

dielectric;

hard biological tissue;

soft biological tissue;

polymer;

plastic; and

composite.

129. The method of claim 98 further comprising:

analyzing the interferometry output to produce an indication of at least one of;

when the material modification source beam has penetrated to a specified depth;

proximity of the region of the material currently being modified to other regions of the material;

remaining amount of material to be penetrated;

total depth that has been modified;

absolute final depth reached;

fluctuations of depth;

speed of depth change; and

remaining distance to a subsurface interface.

107-120. -120. (canceled)