At present, people have been able to make lenses and lens arrays with very small diameters. Such lenses and lens arrays are usually not recognized by the human eye. They can only be observed with microscopes, scanning electron microscopes, atomic force microscopes and other equipment.
The micro lens array is an array composed of lenses with a clear aperture and a relief depth of micrometers. It not only has the basic functions of traditional lenses such as focusing and imaging, but also has the characteristics of small unit size and high integration, making it able to complete the functions that traditional optical components cannot complete, and can form many new optical systems.
At present, there are two main approaches to scientific research to reduce the size of micro lenses and micro lens arrays. The first approach is the binary optical method, which mainly researches the use of photolithography, laser direct writing, gray-scale mask, ion beam etching and other technologies to produce diffractive microlenses and diffractive microlens arrays. The optical elements produced by this method have the surface phase relief structure, the surface shape is discontinuous, this type of micro lens and micro lens array is called diffractive micro lens and lens array.
The second way is to minimize the size of the microlenses while keeping the surface of the lens smooth and continuous, and to array them. The main methods used are colloidal particle self-assembly method, ion exchange method, photosensitive Glass thermoforming method, photoresist hot melt method, photoelectric reaction etching method, focused ion beam etching and deposition method, chemical weather deposition method and other methods, the microlens and microlens array produced by this method are called refractive type micro lens and micro lens array.