Multifaceted prism to cause the overlap of beams from a stack of diode laser bars

• US 7,639,722 B1
• Filed: 10/29/2007
• Issued: 12/29/2009
• Est. Priority Date: 10/29/2007
• Status: Active Grant

• Current Assignee: The Government of United States As Represented By The Secretary of The Air Force, US Department of The Air Force (U.S. Department Of Defense)
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Stohs, Jonathan, Miller, Harold C., Paxton, Alan H.
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): Park; Kinam
• Application Number:
  US11/926,246
• Time in Patent Office: 792 Days
• Field of Search: 372/71, 372/75, 372/70, 359/831, 359/834
• US Class Current: 372/71
• CPC Class Codes: G02B 19/0014 at least one surface having optical power
• CPC Class Codes: G02B 19/0057 in the form of a laser diode array, e.g. laser diode bar semiconductor laser arrays with beam combining arrangement H01S5/4012
• CPC Class Codes: G02B 27/0972 Prisms prisms per se G02B5/04
• CPC Class Codes: H01S 3/0941 of a laser diode
• CPC Class Codes: H01S 5/4012 Beam combining, e.g. by the use of fibres, gratings, polarisers, prisms
• CPC Class Codes: H01S 5/4025 Array arrangements, e.g. constituted by discrete laser diodes or laser bar H01S5/42 takes precedence

Abstract

An optical element for homogenizing and, possibly, concentrating the output from high-power two-dimensional semiconductor laser arrays, which has the basic shape of a convex-flat cylindrical lens with a facet cut into the convex surface for each individual semiconductor laser bar.

Claims

1. A multi-faceted prism optical element for redirecting and superimposing the collimated laser light beams output from stacks of bars of high-power two-dimensional semiconductor laser arrays that are used to pump high average power solid-state lasers, said bars having a center-to-center spacing of d, said optical element comprising:

a. a cylindrical lens blank having a circular cylindrical front surface and a flat back surface that is the output plane of the lens and with a coordinate system centered on said flat surface with a z-axis perpendicular to said flat surface, an x-axis parallel to the central axis of the cylindrical front surface, and a y-axis making up a right hand system, and

b. a plurality of i facets equal to the number of bars and said facets are cut into the circular cylindrical front surface with their coordinates independent of x, such that each facet has its vertices located on said circular surface and said circular surface has a radius r chosen to give the desire value for the distance from the output plane of the lens to a plane at which the beams are approximately superimposed upon each other, said vertices being equally spaced in y given by y_i=(i−

0.5)d, where d is the center-to-center spacing of the laser light output of the bars and said radius is given by r²=y_i²+(z_c−

z_i)² where (y_i, z_i) is the coordinate of the i^th vertex and z_c is the coordinate of the axis at the center of curvature of the circular cylindrical surface, such that said multi-faceted prism redirected said collimated laser light beams to thereby superimpose said beams at a desired distance from the multi-faceted prism.