Optical beam shapers are window-like components that are used in optical systems to alter the final shape of the optical beam.
Beam shapers can be very versatile in the sense that any geometrical shape can be generated from an otherwise simple input beam. Thus, the shape of the output beam can be either a circle, a rectangle or anything else. It can also consist of more complex patterns such as isolated areas or parallel lines.
With this in mind, beam shapers can find applications in a myriad of fields.
For instance, a beam shaper can be used to provide structured illumination such that an image of the target in question, once lit with the illumination from the beam shaper, can provide some insight information. This can be harnessed in lidar applications or 3D sensing devices in general.
A family of beam shapers called vortex phase plates are also used to impart an angular momentum to a beam with a flat wavefront.
A beam with angular momentum has some interesting properties.
They can be used as conveyors of quantum information but perhaps the most practical application is the area of zero energy that arises when the beam is brought to a focus. This type of focused beam is very useful in astronomical coronagraphs to block the light of a distant star, so that it doesn’t swamp the light from nearby objects. It is also useful in high end fluorescence microscopy.
Another function for beam shapers is as beam splitters. A single beam can be used to generate an array of beams, arranged in any dispositions and each new beam in the array sharing the original properties of the original input beam.
Perhaps the most common optical transformation that is pursued in current laser systems deployed in industry is to transform the default Gaussian radiance to a Top Hat or Flat Top radiance distribution. This sort of transformation generates a beam characterised by a beam of constant energy which is well confined within a predefined area.
The most common and practical beam shaper is one that is made with diffractive optics technology.
A diffractive optical element is an array of modulating elements, which can be referred to as pixels, that impart a phase change to an incoming wavefront. Then, by virtue of diffraction effects, a new beam shape arises after some propagation distance, or at the system focal plane. The information related to the desired beam shaping operation is encoded into the pixels by using the mathematical formulae for diffractive optics.
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