Laser beam profile measurement

• US 8,441,625 B2
• Filed: 03/02/2011
• Issued: 05/14/2013
• Est. Priority Date: 03/02/2011
• Status: Expired due to Fees

• Current Assignee: The United States of America As Represented By The Secretary of Agriculture
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Wick, Peter L. Jr.
• Primary Examiner(s): Punnoose, Roy M
• Application Number:
  US12/932,933
• Publication Number:
  US 20120314210A1
• Time in Patent Office: 804 Days
• Field of Search: 356/121
• US Class Current: 356/121
• CPC Class Codes: G01J 1/4257 applied to monitoring the characteristics of a beam, e.g. laser beam, headlamp beam monitoring arrangements for lasers in general H01S3/0014
• CPC Class Codes: G01J 2001/4261 Scan through beam in order to obtain a cross-sectional profile of the beam

Abstract

A method for characterizing a laser beam profile is provided. The method includes disposing a laser target, moving the surface of the target, directing a laser to emit the beam at the surface, measuring a reflection from the surface as intensities, and averaging the intensities. The target'"'"'s surface is disposed substantially perpendicular to an incident direction. The surface is reflective at a wavelength corresponding to the laser beam. The travel direction is substantially parallel to the surface. The laser beam travels along said incident direction to the surface. The reflection represents a plurality of intensities having a distribution of positions along the surface and during a temporal interval. The intensities are averaged over the temporal interval for each position of the distribution to produce an analyzed beam profile. Each position corresponds to a speed along the travel direction based on movement of the surface. The surface can be preferably spun along an axis substantially parallel to the incident beam.

Claims

1. A method for characterizing a profile of a laser beam, said method comprising:

disposing a laser target having a surface substantially perpendicular to an incident direction, said surface being reflective at a wavelength corresponding to the laser beam;

moving said surface along a travel direction substantially parallel to said surface;

directing a laser emitter to emit the laser beam at said surface along said incident direction;

measuring a reflection from said surface, said reflection representing a plurality of intensities having a distribution of positions along said surface and during a temporal interval, and

averaging said plurality of intensities over said temporal interval for each position of said distribution to produce an analyzed beam profile, wherein each said position corresponds to a speed along said travel direction based on movement of said surface.

2. The method according to claim 1, wherein said moving said surface further comprises rotating said surface along an axis substantially parallel to said incident direction.

3. The method according to claim 1, wherein said moving said surface further comprises translating said surface along a roller belt oriented to spin along axes substantially parallel to said surface.

4. The method according to claim 1, further including:

processing said analyzed beam profile by a D4σ

method.

5. The method according to claim 1, further including:

predicting an e² width from said analyzed beam profile.

6. The method according to claim 5, further including:

cropping a periphery from said analyzed beam profile to produce a cropped beam profile for analysis.

7. The method according to claim 6, further including:

applying a non-linear fit routine to said cropped beam profile to produce a resolved beam profile.