Diffractive optical elements or DOEs use light’s wave characteristics to perform their optical function. They transmit light that can be reshaped to almost any desired distribution. They ca be used in various applications without too much light loss. They encode the desired intensity pattern’s shape and maintain other light source parameters. With their design flexibility, DOEs have optical functions that can otherwise not be achieved. Additionally, diffractive optics are usually thinner and lighter than refractive optics, making them the best replacements in some applications. This article explores the different types of diffractive optics solutions and their functions.
Beam splitters work by splitting the incident laser beam into a 1-dimensional or 2-dimensional array of beams. The intervals, symmetrical distribution, and intensity ratios can be chosen freely and are set by microstructures of beam splitters accurately. They are usually used in combination with a focusing lens. The output beam array in this application is turned into an array of focused spots at a certain distance behind the lens. Diffractive beam splitters are often used in multi-focal microscopy, camera calibration, multi-channel splitting for 1D or 2D sensors, and more.
Beam shapers are useful in laser machining, laser eye surgery, and automated water inspection. With these DOEs, an input beam with a known intensity profile into a beam with a different defined output intensity distribution. These DOEs change a Gaussian beam from a laser into a circular or square flat-top beam. Their applications include biomedical devices, lithography, and laser material processing.
Diffractive optics make it possible to create complex patterns with a very high depth of field. The pattern has plenty of spots that are likely to overlap. As the microstructures are highly accurate, the diffraction angles tend to be very precise, especially when using a frequency stabilized laser source. Diffractive pattern generators are used for structured light and pattern projection for 3D sensing applications. They can also be used for aligning and measuring graphics, charts, and range projection.
These DOEs are found in applications such as face recognition. They are often an important element in displays, diffuse- and structured-light systems, and time-of-flight. Diffractive diffusers have surface relief structures configured for diffracting light. These diffractive optical elements are designed using sophisticated simulation algorithms for the generation of certain patterns and intensity profiles. Developers can customize them to generate any speckle-free pattern with almost any intensity profile and field-of-view. They can come up with various light contributions for the application wavelength.