What Is a Fly’s Eye Lens?
A fly’s eye lens is a collection of lenses arranged vertically and horizontally. They are called fly’s eye lenses because they look like the eyes of a fly.
The presence of multiple lenses reduce unevenness in the luminance of the light source compared to a single lens. Uneven luminance is an issue with LEDs compared to conventional light sources. For this reason, they are increasingly used in devices that use LEDs.
The shape of the lens to be placed depends on the case. Sometimes hexagonal lenses are arranged like a honeycomb core, and sometimes rectangular lenses are arranged.
Uses of Fly’s Eye Lenses
Fly’s eye lenses are mainly used in optical applications, especially in devices that require a uniform light source.
One application where fly’s eye lenses are used is in projectors. As applications have become more diverse and the demand for clear images has increased, the brightness of projectors has become higher.
Fly’s eye lenses are used to eliminate the unevenness that becomes more noticeable with higher luminance.
Principle of Fly’s Eye Lenses
A fly’s eye lens is not a single lens, but is composed of multiple lens layers.
The lens closest to the light source is the focus lens. Since light from the light source is weak when irradiated directly onto an object, the light converges and converts into strong energy. The distance between the lens and the area where the light converges is called the focal length. The focal length depends on the refractive index of the lens.
The fly’s eye lens is located in the middle and at the opposite end. The lens in the middle has its convex side facing the light source. It is responsible for spreading the light converged by the focus lens.
The fly’s eye lens at the end, with its flat side facing the light source, spreads the light spread by the second lens more evenly.
Recently, fly’s eye lenses have been used in research to create holographic images. Compared to lasers used in the past, fly’s eye lenses are superior in that they can produce full-color images and can be used in any location.
On the other hand, they are expensive.