Microlenses are miniaturized lenses used in optical transmission systems, in the coupling ofoptical fibers, in lens connectors, EXR sensors ofdigital cameras, cell phone cameras, projectors and in measurement technology.
Microlenses are scattering or focusing lenses whose diameter ranges from a few micrometers to a few millimeters. They are predominantly used where miniaturization and cost savings are critical to customization. Functionally, the light rays in microlenses are refracted according to the laws of physics, just as in normal lenses.
In image sensors, the light rays do not hit the sensors uniformly, which means that the peripheral areas are exposed less than the centers of the image sensors. As a result, distortions and brightness differences can occur in these areas. To eliminate this, microlenses are mounted in front of the image sensors to focus the light optimally. They consist of purified silicon dioxide or silicon and are manufactured in semiconductor processes. Wafer-based manufacturing processes can be used to precisely specify the lens profile and to precisely position microlens arrays( MLA). Such microlenses made of silicon dioxide can be used for all wavelengths between 150 nm and 4 µm. Those made of silicon are suitable for infrared light with wavelengths between 1.2 µm and 15 µm.