Comparing Cylindrical Lenses with Ordinary Spherical Lenses

Ⅰ. What is a cylindrical lens?

Cylindrical lens is generally used to focus incident light on the line or change the image's aspect ratio. It can form a linear image, and the direction of the beam can be controlled. The cylindrical lens has a surface that can focus the incident light in a particular dimension and stretch the image. The focal length of the cylindrical lens can be negative or positive, suitable for laser line generation or deformed beam shaping to circularize Laser output.

 
The principle of the lenticular lens: to add a layer of lenticular lens in front of the LCD screen so that the image plane of the LCD screen can be located on the focal plane of the lens. The image pixels under each cylindrical lens are divided into several sub-pixels so that the lens can project each sub-pixel in a different direction. Therefore, when both eyes look at the display screen from different angles, they see different sub-pixels. However, the gaps between pixels are also enlarged, so sub-pixels cannot be superimposed. Let the cylindrical lens and the pixel column not be parallelled but at a certain angle. In this way, each sub-pixel group can repeatedly project the viewing zone instead of only projecting a group of parallax images to form a 3D image.

Ⅱ. The difference between the cylindrical lens and spherical lens

Compared with ordinary spherical lenses, the production of cylindrical lenses is complicated. Choose materials reasonably, pay attention to the characteristics of material texture, bubbles, impurities, uniformity, etc., and pay attention to product specifications and quality control, such as scratches: Dent, gloss, etc., high-quality grinding technology. In the aspheric lens, a cylindrical lens, the spherical system has the characteristics of describing imaging separately, and it has special functions on some special occasions.

 
Cylindrical lenses are similar to spherical lenses because they all use curved surfaces to focus or diverge light. Still, cylindrical lenses only can converge or split in one direction and will not affect the light in the vertical direction. Suppose a symmetrical output beam is to be produced. In that case, the focal length ratio of the two cylindrical lenses should be the same as the ratio of the central axis to the minor axis of the elliptical beam emitted by the LD. As with standardized collimation, the diode to be measured is placed at the focal point of the two lenses, and the distance between the lenses is equal to their focal length difference.