You must have realized that both spherical and cylindrical optics have a circular profile when viewed end-on. However, there is a common misconception that similar production methods apply to the two optics. The methods used in the fabrication process of these optics use a similar concept of grinding and polishing, but these methods aren’t entirely similar. These optics have different aspects, respond differently to various levels of pressure, stress, and more. Here is what you need to know about the fabrication methods of cylindrical and spherical lenses.
Differences between a cylinder and spherical lens fabrication
Here are the significant areas of differences.
Note that the conventional grinding and polishing usually take advantage of the 360-degree symmetry of a sphere. Cylindrical lenses focus light into a line rather than a point as is the case with spherical. The curved faces of a cylindrical lens are simply sections of a cylinder. They focus the image into a line which is parallel to an intersection of the lens’ surface and the plane tangent to it. This type of lens compresses the image in the specific direction perpendicular to this line.
Also, cylindrical lenses require different fixtures and various grinding geometrics as compared to spherical lenses.
Both cylindrical and spherical lenses are made of different materials. Even if they are made of the same material, they respond differently to strain, stress, and pressure. These differences affect different aspects of the lens fabrication process like the polishing slurry composition and polishing speed. Understanding the differences in how these optical lenses are processed makes it easier for you to choose the right optic that suits your needs.
Most commercial interferometers are specially designed to measure spherical optics. That means that the reference surfaces are always available. This isn’t the case with cylindrical optical lenses. Note that the cylinder metrology needs custom-made optical elements. Besides, they require various vibration-resistant mounts, unlike spherical ones.
Similarities between a cylinder and spherical lens fabrication
The variations in cylindrical and spherical optics fabrication methods are significant. However, they don’t necessarily impact the cost of the elements similarly tolerated by these optics. Note that understanding the differences between the fabrication processes for these optics is important when it comes to the determination of production costs.
Although technological updates are being rolled out regularly for machinery used in the fabrication process of optical lenses, the processing approach in many ways has remained unchanged. Besides, the materials used in the fabrication of these lenses are the same. But this doesn’t mean that the end product is the same.
Optics are a complex concept that most people find difficult to understand. Thus, it’s wise to talk to a professional before you invest in any optic design. The professional can help you motivate your optical design where necessary. If you need cylindrical or spherical lenses, you should also spot a good supplier with inventory capabilities to ensure that you never lack the necessary optical elements.