Understanding Optical Parameter Specifications

In the design and production of a component or system, the use of optical parameter specifications can ensure that the component or system precisely meets the specific performance requirements. Too low or too high parameter specification of optical system will affect its performance and cause resource waste. If the necessary parameters are not set correctly, the specification may be too low and the performance may be reduced. If the parameters are set too strictly, the specifications may be too high, which increases the cost and production difficulty.
1. Production specifications
Diameter tolerance
The diameter tolerance of an optical component indicates the allowable diameter range of the component. This tolerance varies depending on the optical processing technology and the manufacturer's production capacity. Although the diameter tolerance does not directly affect the optical performance, if there is a deviation in the installation of the optical component, the optical axis can be deviated from the mechanical axis, which in turn causes the beam to be eccentric, affecting the performance of the optical system. In general, the tolerance range of the diameter is as follows:
-General quality: +0.00/ -0.10mm
-Precision quality: +0.00/ -0.050mm
-High quality: +0.000/ -0.010mm
Center thickness tolerance
The central thickness of an optical component (especially a lens) refers to the thickness of the material in the central part of the component. The thickness of the center of the lens and the radius of curvature together determine the length of the optical path when the light passes through the lens, thus affecting the optical performance. Therefore, the accuracy of the center thickness is crucial. Common tolerance standards are:
-General quality: +/ -0.20mm
-Precision quality: +/ -0.050mm
-High quality: +/ -0.010mm
Radius of curvature
The radius of curvature is the distance from the apex of the surface of the optical element to the center of curvature. This radius affects the path length of light passing through the lens or mirror and determines the surface power of the optical system. In general, the tolerance range of the radius of curvature is:
-Common application: +/ -0.5mm
-Precision application: +/-0.1%
-High precision application: +/-0.01%
2. The centrality and deviation of optical components
The centrality (also known as centrality) of a lens describes the deviation between the mechanical and optical axes of the lens. To test the centrality of the lens, pressure can be applied by placing the lens inside a stationary container, such as a teacup. At this point, the center of curvature of the lens will align with the rotation axis of the container. If the lens is centrifugal, the beam will deviate as it passes through the lens, forming an out-of-focus circular trajectory in the back focal plane.
3. Parallelism
Parallelism describes the relationship between two parallel surfaces. In some optical components (such as window pieces, polarizers, etc.), surface parallelism is critical to system performance because parallel surfaces minimize distortion and ensure image or beam quality. In general, tolerances for parallelism can range from a few arcs to a few arcseconds.
4. Angle tolerance
In optical components, the Angle error between surfaces directly affects the optical properties. For example, the angular tolerances of prisms and spectroscopes are crucial for accurate refraction and splitting. Angular tolerances are generally measured with a collimator telescope. Collimator telescopes use parallel light sources and rotate around the surface of the optical element until a precise Angle error is detected. Angle tolerances can range from a few arcs to a few arcseconds.

By understanding and correctly setting the production specifications of optical components, the performance of optical systems can be ensured to the maximum extent during the design and manufacturing process. Reasonable parameter specifications not only help to optimize optical performance, but also reduce production costs and difficulties. Therefore, in the design of optical components, accurate control of key parameters such as diameter tolerance, center thickness tolerance, curvature radius, and pay attention to centripetal, parallel and angular tolerance can effectively improve the overall performance of the system. For high-precision applications, detailed tolerance control is particularly important to ensure the stability and efficient operation of the optical system.