Qioptiq: Lenses with integrated beam splitter prism
28 Feb 2012
Qioptiq has been paying special attention to the issue of light input into the beam path for high resolution applications with linescan sensors. Macro lens versions with light input for sensor sizes of up to 2/3" have been available on the market for many years now. Almost every lighting vendor offers coaxial incident light modules, positioned between object and lens, for non-critical imaging scales. This solution however is not suitable for high resolutions of 5 microns or below in combination with an optical magnification of >1. Simulations at Qioptiq showed that the beam splitter plates installed at an angle lower than 45° to the optical axis provide a very high astigmatism, considerably distorting the optical image.
This astigmatism can be eliminated completely using a beam splitter prism instead of a plate. The prism however is considered by the projection beam path as a lens with relatively large central thickness and infinite radii. Using diffraction-limited inspec.x L lenses by Qioptiq combined with long linescan sensors will cause the prism to generate a poor imaging performance, especially at the edge. This image quality loss is not acceptable for various applications using inspec.x series lenses.
Qioptiq was able to optimise their inspec.x L lenses with 3x, 3.5x and 5x magnification in such a way that a diffraction-limited image quality can be achieved again. Since the precision requirements for the prism and its positioning in the beam path are tremendous for the required resolutions, Qioptiq designed a prism module which is perfectly matched for inspec.x L lenses. It can be easily mounted on the lens and facilitates azimuthal alignment. The module offers the typical Qioptiq industry-grade quality and is optimised for optical fibre use. It provides a universal interface that connects to common line lights.
First operational tests provided outstanding results in terms of image quality of the overall system and ease of use. Using this solution, scanning applications with resolutions in microscopic ranges can be realised.
Qioptiq designs and manufactures photonic products and solutions that serve a wide range of markets and applications in the areas of industrial manufacturing, medical and life sciences, research and development, defence and aerospace.