Energy beam size verification

• US 9,664,504 B2
• Filed: 03/22/2016
• Issued: 05/30/2017
• Est. Priority Date: 08/20/2014
• Status: Active Grant

• Current Assignee: Arcam Ab (Danaher Corporation)
• Original Assignee: Arcam Ab (Danaher Corporation)
• Inventors: Snis, Anders
• Primary Examiner(s): Kim, Kiho
• Application Number:
  US15/077,155
• Publication Number:
  US 20160202042A1
• Time in Patent Office: 434 Days
• CPC Class Codes: B22F 10/28 Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
• CPC Class Codes: B22F 10/31 Calibration of process steps or apparatus settings, e.g. before or during manufacturing
• CPC Class Codes: B22F 12/52 Hoppers
• CPC Class Codes: B22F 12/90 Means for process control, e.g. cameras or sensors
• 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 15/0086 welding for purposes other than joining, e.g. built-up welding
• CPC Class Codes: B23K 15/02 Control circuits therefor
• CPC Class Codes: B23K 26/032 using optical means
• CPC Class Codes: B23K 26/04 Automatically aligning, aiming or focusing the laser beam, e.g. using the back-scattered light
• CPC Class Codes: B23K 26/046 Automatically focusing the laser beam
• CPC Class Codes: B23K 26/082 Scanning systems, i.e. devices involving movement of the laser beam relative to the laser head
• CPC Class Codes: B23K 26/342 Build-up welding
• CPC Class Codes: B23K 26/70 Auxiliary operations or equipment
• CPC Class Codes: B33Y 10/00 Processes of additive manufacturing
• CPC Class Codes: B33Y 30/00 Apparatus for additive manufacturing; Details thereof or accessories therefor
• CPC Class Codes: B33Y 40/00 Auxiliary operations or equipment, e.g. for material handling
• CPC Class Codes: B33Y 50/02 for controlling or regulating additive manufacturing processes
• CPC Class Codes: G01B 11/00 Measuring arrangements characterised by the use of optical techniques
• CPC Class Codes: G01B 11/14 for measuring distance or clearance between spaced objects or spaced apertures G01B11/26 takes precedence; rangefinders G01C3/00
• CPC Class Codes: G01B 15/00 Measuring arrangements characterised by the use of electromagnetic waves or particle radiation, e.g. by the use of microwaves, X-rays, gamma rays or electrons characterised by the use of optical techniques G01B9/00, G01B11/00
• CPC Class Codes: G01M 11/02 : Testing optical properties
• CPC Class Codes: G01P 21/00 : Testing or calibrating of apparatus or devices covered by the preceding groups
• CPC Class Codes: G01P 3/36 : Devices characterised by the use of optical means, e.g. using infrared, visible, or ultraviolet light G01P3/68 takes precedence; gyrometers using the Sagnac effect, i.e. rotation-induced shifts between counter-rotating electromagnetic beams G01C19/64
• CPC Class Codes: H01J 37/244 : Detectors; Associated components or circuits therefor
• CPC Class Codes: Y02P 10/25 : Process efficiency

Abstract

A method for verifying a size of an energy beam spot, said method comprising the steps of providing a first beam spot having a predetermined size and power at a first position on a work piece, varying a focus and/or astigmatism lens setting for said first beam spot until max intensity for the beam spot is detected, comparing the detected settings of said focus lens and/or astigmatism lens for said maximum intensity of the beam spot with stored settings of said focus lens and/or astigmatism lens for the beam spot with said predetermined size and power, repeating step a-c for different predetermined beam powers, repeating step a-d for different positions on said work piece, wherein said beam spot size is verified if each detected settings of said focus lens and/or astigmatism lens are deviating less than a predetermined value from corresponding stored settings of said focus lens and/or astigmatism lens.

Claims

1. A computer-implemented method for automatically verifying a size of at least one energy beam spot, said method comprising the steps of:

(a) generating a first energy beam spot from a first energy beam source, the first energy beam spot having a predetermined size and power at a first position on a work piece, wherein said first position is detected by at least one of an IR-camera, a CCD-camera, a digital camera, a CMOS camera, or a NIR-camera,

(b) varying, via at least one control unit containing a processor, at least one of a focus lens setting or an astigmatism lens setting for said first energy beam spot until a maximum intensity of the first energy beam spot is detected,

(c) comparing, via said at least one control unit, at least one setting of said focus lens and/or astigmatism lens associated with said detected maximum intensity of the first energy beam spot with corresponding stored settings of said focus lens and/or astigmatism lens associated with said predetermined size and power of the first energy beam spot, the stored settings being stored within a memory,

(d) repeating, via said at least one control unit, steps a-c for different predetermined beam powers, and

(e) repeating, via said at least one control unit, steps a-d for different positions on said work piece, and verifying said first energy beam spot size by verifying that each of said focus lens and/or astigmatism lens settings associated with the detected maximum intensity deviate less than a predetermined value from the corresponding stored settings of said focus lens and/or astigmatism lens.

2. The computer-implemented method according to claim 1, wherein said predetermined energy beam spot size is a minimum spot size.

3. The computer-implemented method according to claim 1, wherein the repeating step for different positions is performed before the repeating step for different predetermined beam powers.

4. The computer-implemented method according to claim 1, wherein the first energy beam spot is an electron beam spot.

5. The computer-implemented method according to claim 4, wherein said astigmatism lens and/or focus lens settings comprise a coil current setting to at least one astigmatism coil and/or at least one focus coil respectively.

6. The computer-implemented method according to claim 1, wherein the first energy beam spot is a laser beam spot.

7. The computer-implemented method according to claim 6, wherein said astigmatism lens and/or focus lens settings comprise a positioning along an optical axis of at least one astigmatism lens and/or at least one focus lens respectively.

8. The computer-implemented method according to claim 1, further comprising a step of sending a warning signal/message when any one of said settings of said focus lens and/or astigmatism lens associated with the detected maximum intensity deviate more than a predetermined value from the corresponding stored settings of said focus lens and/or astigmatism lens.

9. The computer-implemented method according to according to claim 1, further comprising the steps of:

providing a second energy beam spot from a second energy beam source, the second energy beam spot having a predetermined size and power at said first position on said work piece,

varying a focus and/or astigmatism lens setting for said second energy beam spot until a maximum intensity for said second energy beam spot is detected, and

comparing said detected maximum intensity for said first energy beam spot with said detected maximum intensity for said second energy beam spot, and verifying said first and second energy beam spot sizes by verifying that said detected maximum intensity of said first energy beam spot deviates less than a predetermined value from said detected maximum intensity of said second energy beam spot.

10. The computer-implemented method according to claim 9, wherein said first and second energy beam spots have equal maximum beam spot power.

11. The computer-implemented method according to according to claim 1, further comprising the steps of:

providing said first energy beam spot at said first position during a first predetermined time duration where a first intensity is detected,

providing said first energy beam spot at said first position during a second predetermined time duration where a second intensity is detected, and

calculating a ratio between said first and second intensities, and verifying said first energy beam spot size and/or beam spot power by verifying that said calculated ratio between said first and second intensities deviates less than a predetermined value from a corresponding calibrated ratio of said first beam energy spot with said first and second time durations.

12. The computer-implemented method according to claim 11, wherein steps therein are repeated for different beam powers and/or time durations.

13. The computer-implemented method according to claim 1, wherein:

the method further comprises the step of receiving and storing, within one or more memory storage areas, a model of at least one three-dimensional article; and

at least one of the varying, comparing, or repeating steps is performed via execution of one or more computer processors.

14. The computer-implemented method according to claim 1, wherein:

the method is further configured for verifying a deflection speed of the first energy beam spot; and

the method further comprises the steps of;

generating a predetermined pattern on a work table with said first energy beam spot while deflecting said first energy beam spot with a first deflection speed;

detecting first positions of said first energy beam spot on said work table created with said first deflection speed;

generating said predetermined pattern on the work table with said first energy beam spot while deflecting said first energy beam spot with a second deflection speed;

detecting second positions of said first energy beam spot on said work table created with said second deflection speed; and

comparing said first and second positions, verifying that each one of said first positions deviate less than a predetermined distance from corresponding ones of said second positions.