Designing and manufacturing an optical component or system requires optical specifications to characterize how well it meets some performance requirements. Such specifications specify the acceptable limits of major parameters that govern system performance and the amount of resources to be spent on manufacturing. These specifications include the following:
Following the completion of a design, the characteristics of every optical surface in the system tolerance are determined. Surface accuracy describes the maximum allowable deviation of an optical surface from a perfect surface.
A circular optical component’s diameter tolerance offers an acceptable range of values for the diameter. While this specification doesn’t impact the optic’s optical performance, it must be considered when the optic will be mounted in any kind of holder.
Because glass corners are quite fragile, they should be protected when handling or mounting a component. Beveling the edges is one of the most effective ways to protect the corners. Optics that have diameters less than 3.00 mm like micro lens or micro-prisms are often not beveled because of the potential of making edge chips in the process.
This refers to the maximum allowable deviation between the optical and mechanical axes for a spherical lens. The centering process also defines the diameter tolerance that is often +0. Typically, the centration of lens is specified by the deviation angle, but it is often tested at double the value while the lens is rotated.
This is associated with the lens or spacing between elements. For flat surfaces, the production of large sheets of non-polished glass produces bigger variances in thickness. For curved surfaces, ±0.1mm is the reasonable operating tolerance. Thickness tends to vary depending on sheet size and where the measurement is made on the sheet.
An optical surface’s quality describes its cosmetic look and includes defects like scratches and pits or digs. Usually, such surface defects are purely cosmetic and don’t have an impact on system performance.
This measures small scale irregularities on a surface. Rough surfaces wear faster than smooth ones and may not be suitable for some applications, particularly those with intense heat or lasers, because of potential nucleation sites that can appear in small cracks or imperfections.
Prism Angle Accuracy
The relative angle between the reflecting surfaces must have a critical tolerance to maintain a maximum acceptable angular deviation. But, depending on the system’s placement, the other angles may have a tolerance to limit aberration effects.