A microlens array refers to an array of a number of microsized lenslets that bear the same shaped organized in a regular pattern like hexagon or square. The subunit size of such microlens product is 32μm to 1500μm and the focal length ranges between 0.8 mm to 50 mm. The shape of every subunit could be in a square, round or hexagonal in shape. The microlens array or fly eye lenses is commonly used in Hartmann wavefront sensor, also denoted as HSWFS, beam splitting, laser homogenization, beam focusing, wavefront sensing, and collimation.
They come in handy for homogenizing many modern light emitters ranging from line narrow excimer lasers to the high power LEDs. Microlenses are perfect for applications that need high efficiency and non-gaussian uniformity. All the microlens arrays are made from UV grade fused silica that gives an amazing performance from 193 nm to 2.5 μm. The microlens arrays are made with the standard semiconductor technologies that yield perfect shaping of the lens profile and exact positioning of the lenses in an array. There are two configurations of arrays.
Square microlens arrays
These are available in a standard 10 mm x 10 mm configuration in a number of lens pitch and focal length options. Square microlenses are generally used for beam homogenization and shaping that yields spot patterns or a square flat top pattern. These lenses have a high fill factor that gets rid of the zero order hot spots in the illuminated field. Square lenses can be used in pairs along with a PCX lens. Applications of these arrays are drilling, welding, fiber coupling, and laser ablation.
Fly’s Eye Condenser Arrays
These eye condensers arrays are available in 5 mm and 10 mm square configurations and are meant for flat top and line generation. These condenser arrays are deemed a monolithic assembly of dual surface cylindrical microlenses that make condensers which are free of all kind of adjustments. These microlenses are usually common in applications needed a huge illuminated field with short working distance like medical laser use, UV curing, solar simulation, semiconductor instrumentation and fluorescence microscopy. Now here are the Specifications Of Micro lens Array:
- Coated: uncoated
- Substrate: fused silica
- Lens profile: spherical
- Dimensional tolerance: ±0.05 mm
- Pitch Tolerance: ±0.25 μm
- Wavelength Range :200 – 2200 nm
Parameters of Microlenses arrays
- The material and size of microlens
- Shape: spherical mirror, cylindrical lens, non-cylindrical lens, aspheric lens, and astigmatic lens.
- Arrangement: hexagonal arrangement, square array, random arrangement etc.
- Microlens cycle, focal length, etch depth, curvature radius.