New way to produce diamond-turned mirrors situates them early on


Jena, Germany--Researchers at the Fraunhofer Institute for Applied Optics and Precision Engineering (IOF) have worked out a way to produce diamond-turned telescope mirrors to what they say is a better surface figure and mirror-to-mirror positional accuracy. Mirrors have been built for an IR sounder telescope (IRS-TEL) using the technique. (The photo shows the telescope's M2/M3 assembly with two exactly aligned aspherical mirrors produced using the technique.)

Optics for certain space-research, climate-observation, and weather-forecasting satellites consist of several aspherically shaped mirror elements that form a telescope. "All the mirrors must be produced and characterized with extreme precision, that is to an accuracy of less than one micrometer," explains Sebastian Scheiding of the IOF. "They also have to be exactly positioned in relation to each other."

Until now this positioning has been very time-consuming, as it takes place step by step. First, the individual mirrors are fitted in the telescope one after the other, then the imaging quality is measured. If errors are found, they are corrected by positional adjustments to the mirrors. Then further measurements and adjustments are made until all components are optimally arranged.

Optics positioned together during diamond-turning
"We wanted to simplify this complicated and time-consuming adjustment process," says Scheiding. In the research project, which was initiated by the German Aerospace Center (DLR), Scheiding developed an new production technique which takes into account the later alignment of the components right from the outset. For this purpose, the individual mirror surfaces are positioned in relation to each other as precisely during processing as they will be later in the telescope. This reduces to a minimum the errors and corrections made when the mirrors are being fitted. The assembly process is simple and reproducible.

"The trick is that we mount all the mirrors for a module in the same machine at the same time and assign them to a common system of coordinates. To this end, each mirror blank is provided with defined, ultraprecise measurement marks and reference surfaces," says Scheiding.

The fixed marks define the coordinate system for diamond-turning of the mirror shapes. At the same time, however, they fix the position of each mirror in relation to the adjacent mirrors. Finally they also serve as reference points for subsequent measurement processes to check the quality of the optical system.

The mirror arrangement for the IRS-TEL contains two mirror modules, each of which has two juxtaposed aluminum mirror surfaces. The shape of the metal mirror deviates a maximum of 126 nm from the ideal aspherical shape and the position of two mirrors in relation to each other is said to be ten times more precise than for comparable conventionally produced mirror assemblies.

Less expensive too, says IOF
"As a result, we can make optical systems of this type to a far greater degree of accuracy, but at the same time we're cheaper because the time-consuming adjustment process during final assembly is no longer required," says Scheiding.

The IOF's mirror module is on display at Hall 3, Stand D50 at the OPTATEC international optical trade show from June 15 to 18 (Frankfurt, Germany).


 --posted by John Wallace

Laser Focus World


Get All the Laser Focus World News Delivered to Your Inbox

Subscribe to Laser Focus World Magazine or email newsletter today at no cost and receive the latest news and information.

 Subscribe Now

Most Popular Articles


Understanding Polarization and Optical Coatings

Light is an electromagnetic wave, but, at optical frequencies, it is its electric field that interacts with materials, with the direction of the electric fie...

Wave Optics Simulations

An add-on to COMSOL Multiphysics®, the Wave Optics Module offers capabilities for modeling optical phenomena. The innovative beam envelope method is among th...

Lens Design – Tools for designing manufacturable aspheres for complex optical assemblies

Designing aspheres that may be successfully fabricated and tested can be a frustrating experience. The range of possible aspheres is much larger than the ran...

Ray Optics Simulations with COMSOL Multiphysics

The Ray Optics Module can be used to simulate electromagnetic wave propagation when the wavelength is much smaller than the smallest geometric entity in the ...
White Papers

High-Power Diode Lasers under External Optical Feedback

We carried out a comprehensive study on single emitters with different antireflection (AR) coatin...

LED Reflector and Lens Simulation using TracePro® Illumination Design and Analysis Software

TracePro® allows users to design, analyze, and optimize LED lighting systems using software simul...

Degradation studies of a VECSEL gain structure using a stable green pump laser

The degradation of the gain structure of a red-emitting Optically Pumped Semiconductor (OPS) Vert...
Technical Digests
There is no current content available.

Click here to have your products listed in the Laser Focus World Buyers Guide.


Synopsys' CODE V Version 10.4 is now generally available

03/30/2012 Synopsys' CODE V Enhances Analysis of Precision Optical Systems.

Scratch-resistant mirror with gold surface

03/12/2012 In the LINOS catalog from Qioptiq you will now find the scratch-resistant mirror with gold surface.
Social Activity
Copyright © 2007-2014. PennWell Corporation, Tulsa, OK. All Rights Reserved. PRIVACY POLICY | TERMS AND CONDITIONS