What Is a Microlens Array?
A microlens array is an optical lens array consisting of multiple micron-sized lenses.
Since the size of a lens is quite small (a few microns), the focal length of the lens is a few millimeters, which is a very short distance. Recently, demand for microlens arrays has been rapidly increasing, partly due to the trend toward thinner and smaller electronic devices such as smartphones and digital cameras.
Uses of Microlens Arrays
Microlens arrays are mainly used in the field of optics, such as optical communications, displays, observatory telescopes, and lighting.
The main roles of microlens arrays are light focusing and diffusion. One of the devices used for light collection is a digital camera. By further focusing the light collected by the camera’s lens, more accurate optical information can be delivered to the image sensor.
Conversely, the ability to efficiently diffuse minute amounts of light makes it ideal for use in medical equipment, aircraft, and other applications.
Principle of Microlens Arrays
Microlens arrays can deliver aggregated optical information to the next medium by focusing light diffused by an array of microlenses. As mentioned earlier, this is a function often used in conjunction with image sensors in cameras.
A similar function is also applied to optical fiber. The cross-sectional structure of an optical fiber consists of a protective layer on the outside that protects the line and a thin tube of about 50 µm called a “core” in the center. This is where the light passes through, and to transmit optical information, the light emitted from the light source must accurately enter the core. Therefore, microlens arrays are used to collect light and guide it toward the core, enabling efficient and accurate transmission of optical information.
The ability of microlens arrays to collect and diffuse light depends on the shape, size, number, and position of each lens. It is important to select the appropriate one in consideration of the intended use and application.