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Beam Shaping and Its Application

Beam Shaping and Its Application

Most laser beams’ radiance profile can be understood by the mathematical formalism of the Gaussian mode or Gaussian profile. In a Gaussian profile, the irradiance level reaches its maximum value at the central point and gradually drops towards the edges. Therefore, the non-uniformity in the Gaussian profile’s irradiance level results in a noteworthy energy loss. Due to this reason,one often can not use natural laser beams in various industrial and scientific applications. To make laser beams applicable for applications such as printing, material processing, medical treatments, imaging, communications, sensing, and additive manufacturing, we need to shape the laser beam so that its inherent radiance pattern gets changed, resulting in the prevention of energy loss. Beam shaping is a method to introduce sharp edge and uniform central radiance in the laser beams. Whereas the absence of sharp edges results in energy loss in the Gaussian profile, beam shaping method helps shape the beam to overcome the issue and attain a unique spot shape with a consistent irradiance level. 

Beam Shaping Applications

There are various medical and industrial applications of beam shaping methods. The noteworthy industrial applications of beam shaping methods are laser scribing, welding, ablation, and metal and glass cutting. In the medical field, beam shaping methods have crucial applications in aesthetic treatments, including body contouring, tattooing, and hair removal. Other applications of beam shaping include sensing, printing, additive manufacturing, material processing, communications, medical treatments, etc. In medical diagnostics and spectroscopy, beam shaping methods also have useful applications. 


Different Types of Beam Shaping Methods

The three most common types of beam shaping methods are- I. Single-mode laser solutions, II. Multi-mode laser solutions

There are three main ways to achieve a single-mode laser solution, being:  a. angular  Top Hat beam shaping, b. focal Top Hat beam shaping c. Mode converters such as Vortex mode generators. The aim of angular beam shaping solutions is to achieve a Top Hat intensity distribution at the focal plane of an external diffraction-limited lens. The size of the spot is dependent on the lens EFl and the same shaper can be used with different lenses to give different shape sizes. On the other hand, focal beam shaping methods use hybrid optical elements to achieve the same intensity distribution at a certain working distance, i.e they incorporate the lens into the component. 

Mode converters change the basic gaussian mode of a single mode laser into a higher mode, often a donut shaped mode generated by spiral phase plates. These types of shaping are extremely  stable but limited to predetermined mode shapes of rings or lobes.

Diffractive diffusers and broadband diffusers help  achieve multi-mode laser solutions. The flat top diffractive diffusers are useful for spot shaping to any desired shape, including round, line, square, and rectangular. Broad band diffusers operate in a mixed refractive- diffractive regime, allowing them to shape multimode beams to flat tops over a broad range of wavelengths.

Principles of Beam Shaping

Beam shaping can be done by using either diffractive or refractive principle. Top Hat beam shapers and diffractive diffusers follow the diffractive principle, whereas Micro-lens arrays work based on the principle of refraction. Some elements, such as broadband diffusers , combine both methods.