Diode laser array beam homogenizer
A means of achieving a spatially uniform output beam from a laser diode array with minimal design complexity is provided. The means is comprised of one or more optical elements located adjacent to the output of the diode array, the optical element(s) reducing the divergence of the output of the individual emitters of the diode array in at least one axis to within an acceptable range, preferably within the range of 0.1 to 10 degrees. The means is further comprised of a diffusing element, the output of the emitters passing through the optical element(s) prior to passing through the diffusing element. The diffusing element, preferably either a holographic diffuser or an engineered diffuser™ which provides control over the light diffusion angles, smoothes out the ripples formed by the overlapping output beams of the emitters in order to achieve the desired spatially uniform beam.
1 . A laser system comprising:
a diode laser array comprised of a plurality of emitters, wherein each of said plurality of emitters emits an output beam from an output facet;
an optical element adjacent to said output facets of said plurality of emitters of said diode laser array, said optical element reducing beam divergence in at least a first axis of said output beams of said plurality of emitters; and
a diffusing element adjacent to an output side of said optical element.
2 . The laser system of claim 1 , wherein said optical element reduces said beam divergence in said at least said first axis to within a range of 0.1 to 10 degrees.
3 . The laser system of claim 1 , wherein said optical element is a cylindrical lens.
4 . The laser system of claim 1 , wherein said optical element is an aspheric cylindrical lens.
5 . The laser system of claim 1 , wherein said optical element is comprised of a plurality of lens elements, said plurality of lens elements corresponding to said plurality of emitters.
6 . The laser system of claim 5 , wherein said plurality of lens elements is comprised of a plurality of cylindrical lenses.
7 . The laser system of claim 1 , wherein said optical element is comprised of a first beam divergence reducing element and a second beam divergence reducing element.
8 . The laser system of claim 7 , wherein said first beam divergence reducing element reduces the divergence of said plurality of emitters in a first axis and said second beam divergence reducing element reduces the divergence of said plurality of emitters in a second axis.
9 . The laser system of claim 7 , wherein said first beam divergence reducing element is a cylindrical lens and said second beam divergence reducing element is a microlens array wherein each microlens of said microlens array corresponds to an individual emitter of said plurality of emitters.
10 . The laser system of claim 1 , wherein said diffusing element is a holographic diffuser.
11 . The laser system of claim 1 , wherein said diffusing element is an engineered diffuser™.
12 . The laser system of claim 11 , wherein said engineered diffuser™ is a lenticular diffuser.
13 . A method of achieving a spatially uniform beam from a diode laser array comprising the steps of:
reducing divergence in at least a first axis of each of a plurality of output beams from said diode laser array to within a range of 0.1 to 10 degrees;
diffusing each of said plurality of output beams after said divergence reducing step; and
overlapping said plurality of output beams after said diffusing step to form said spatially uniform beam.
14 . The method of claim 13 , wherein after said divergence reducing step divergence in said first axis and a second, orthogonal axis of each of said plurality of output beams is within the range of 0.1 to 10 degrees.