Toroidal mirrors are constructed by revolving a spherical curve along an axis. It can be symmetry or asymmetry. The revolving curve is circle with radius R. The center distance from the curve to the revolving axis is r. When those two numbers are same, it is sphere. However, when those two numbers are not same, it is a Toroid.
Toroid is a geometry commonly used in x-ray optical system. For the point source, the incoming beam angle stays at constant angle for all points on the mirror. In x-ray optics, the reflection is governed using Bragg’s law. This constant angle requirement makes Toroidal Mirror so special in x-ray optical systems. Toroid mirror is also used often in laser for beam shaping.
In Today’s fabrication method, there are mainly two types of Torodial Mirrors, diamond turned and free form polished glass. The diamond turned mirror can only be made out of copper, aluminum, Nickel, Ge, and occasionally Si. Due to its material limitation, diamond turned toroids are limited mostly for laser beam shaping. Glass or other polish-able materials can be grounded and polished into a precision Toroidal mirror. This method can produce high precision Toroial mirror at various size but contain a very high manufacturing cost.
Toroidal mirror has a complicated testing geometry in manufacturing. We always say that you can only make an optics to be as good as you can test it. The common testing method for Toroidal mirror is CGH, 3d profile, or some specially engineered testing method. Not all testing methods are created equal – some of testing methods have size limit; some of the testing methods have precision limit; and some testing method are cost effective but have its own limit.
With 15 years of experience in making high precision Toroidal optics, we can determine the proper specification, material choice, manufacturing method, design for manufacturing, and testing method for your need. Our mission is to make the finished optics affordable and the most adequate precision for the application. If you have a Toroidal mirror project, we are happy to assist you with finding the best solution to meet your application’s need.