Microlens arrays are the combination of two or more small lenses (also called as lenslet). Their number is usually a thousand or a million and it creates a periodic pattern of a square or hexagon. They are usually identified in three forms- a thin transparent layer, homogenous glass, and semiconductor substrate.
For understanding them better, here are some important properties of Micro lens that are worth considering:
The operating principle of Micro Lens: Depending on the construction and configuration, Microlens is based on the following principle:
- Some Microlens simply works as refractive lenses (also called as traditional large lenses). Such a lens has the potential to radially change the optical phase and the thickness of the device.
- To lower the thickness of the lens, the Fresnel lens is used to reflect the light by a set of concentric curved surfaces.
- Diffractive microlenses are based on the phenomenon of diffraction. While the refractive lens is useful in large devices, diffraction effects are helpful for small dimensional elements.
- With the latest hi-tech upgrades, now many optical dealers also provide ‘Gradient-index lenses (GRIN lenses)’, which are typically used to assemble and re-image the output of the fiber, coupling the output of diode lasers into fibers and focusing the laser light onto a detector.
Functional Parameters of Micro Lens: It’s important to know that every lens varies on the following aspects:
- Microlens can be optimized on aspects like spectral ranges, optical material, and the layers of anti-reflection coatings.
- Every Microlens has different values of lens pitch; ranging from a few micrometers to hundreds of micrometers. Nevertheless, if you are into industries such as photography or medical science, lens position with high accuracy and precision is needed.
- Consider the characteristic of the lens like diameter, focal length, and wavelength.
- The lens is generally available in circular or cylindrical shape, which can be customized as per the customer’s request.
Ask about the fabrication technique: Microlenses are engineered with different fabrication techniques such as:
- Some Microlenses are manufactured by computer-controlled laser writing technologies, especially when the client needs customized designs.
- Microlens is also made by hot embossing or injection molding from some master form.
- In other cases, traditional techniques like lithography, photolithography, and computer-generated holograms are used.
In many industries, Microlenses are playing a significant role in stimulating the overall performance of the devices. So make sure you consider the above properties without fail.