Optical (or light) diffusers are devices that redistribute light into a desired pattern.
For example, a collimated beam can be incident upon a diffuser, resulting in emerging light that spans a wide range of directions.1
The diffusion characteristics can differ between devices. Some may have Lambertian characteristics, while others have a Gaussian-shaped scattering.2
When a diffuser offers Lambertian reflectance, the apparent brightness of the light is the same to the observer, no matter which way they look at it. In Gaussian shaped scattering, or in other angularly tuned distributions, the light can appear brighter or less bright depending on the angle the observer is looking from.
This opens up possibilities across multiple applications for optical diffusers and structured surfaces.
Operation Principle of Optical Diffusers
A diffuser works to angularly redistribute light, either in transmission or reflection. Some examples include:
- White ceramics or a sandblasted optical surface.
- Light transmission through the ground or chemically etched glass (frosted glass).
- Plastic or glass optics with prismatic features.
The desired performance of an optical diffuser is highly dependent on the application. Performance is considered through the spatial characteristics of outgoing light.
In most cases, it’s desirable to have high efficiency or the highest amount of incoming optical power scattered onto the appropriate range of output angles. Usually, the minimum absorption is desirable to have the brightest light output with the lowest heating effects.
Some applications require specialized optical properties that may be more challenging to achieve, such as:
- Scattering that occurs in one direction and not in perpendicular directions.
- Angular distribution may be independent of the optical wavelength.
- Scattering limits to specific regions of a plane.
- High-performance or special requirements that may be achieved only by using high-quality engineered diffusers.
Applications of Optical Diffusers
Optical diffusers have a wide range of applications for both household and industrial use.3 These include:
- Integrating spheres: In optical metrology, an integrating sphere has a high-quality diffusive coating that uniformly scatters incoming light with the minimum amount of absorption.
- Screens and displays: Screens and displays for devices need high scattering (diffusing) light to work correctly. This is especially true of laser projectors, which need diffusive properties for high-quality images.
- Illumination: Diffuse light is desirable for illumination and provides uniform light intensity. This is typical of street lights, which must give excellent light intensity along with high uniformity. Other examples include interior lighting and LED illuminators.
AOS Works With Viavi Solutions (RPC Photonics) Optical Diffusers
Viavi Solutions Engineered Diffusers offer more advanced technology for optical diffusers with superior performance and specialized applications. Unlike conventional diffusers, Engineered Diffusers expand beyond Lambertian patterns to include elliptical, square, uniform, non-uniform, or custom scatter patterns.
Diffusers are created with pseudo-random microlens arrays that act as a scattering center, but each microlens element is designed and controlled individually. This allows the user to control the scatter distribution’s size, shape, and profile. Engineered Diffusers can also operate in broadband light or monochromatic illumination.
With the fabrication process, Engineered Diffusers have the capability of sharp edges in a scatter pattern and a 100 percent fill factor. These can be designed for angles as small as 0.25 degrees or as large as a whole hemisphere.
AOS Injection Molding for Optical Diffusers
Apollo Optical Systems (AOS) molding technology produces high-quality parts according to industry standards as the exclusive injection molder for Viavi Solutions Engineered Diffusers. We fabricate consistent and high-quality custom optical diffusers according to the needs of the customer.
With the strategic partnership, AOS handles all critical capabilities to ensure program success, such as mold design, optical component design, system design, low- and high-volume assembly, and a scientifically approached mold process.
Realize Your Project Goals with Apollo Optical Systems
We have the knowledge and experience to help you develop the right solution for your optical project with our in-house expertise and strategic partnerships. Contact us for your custom optical and mechanical design solutions!
Sources:
[1] https://www.rp-photonics.com/diffusers.html [2] https://www.rp-photonics.com/lambertian_emitters_and_scatterers.html [3] https://www.rp-photonics.com/diffusers.html [4] https://www.rpcphotonics.com/engineered-diffusers-information/