Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Cost-saving Laser-based Process for Manufacturing Free-form Optics

12.04.2012
There is a growing demand for non-spherical glass optics. Currently, these optical elements – for example lenses for cameras or multifocal glasses – are still very costly to manufacture.
The Fraunhofer Institute for Laser Technology ILT has developed a process for manufacturing optical glass components, which should be particularly suitable for the cost-effective production of aspheres and free-form optics. With this procedure, engineers will be able to produce nearly every surface geometry imaginable in the future.

In optical systems such as headlights, projectors, camera lenses and lenses for glasses, optics ensure that light is focused as well as significantly determining image quality due to their surface form and finish quality. With commonly used spherical optics, the risk of aberration typically is reduced through combining several optics in a single optical system. However, this approach also increases the weight and size of the optical system. By using non-spherical lenses, whose surface form deviates from the spherical curvature of a spherical lens, engineers can effectively minimize such aberrations. This way, two or more conventional spherical optics can be replaced by one asphere and enable higher luminous efficacy. In addition, the dimensions and the weight of the overall optical system can be reduced.
Until now, small quantities of non-spherical optics have been produced through a number of expensive and time-consuming grinding and polishing steps. While the blank pressing of optics represents one possible alternative, it, however, is only economical for larger quantities. A young research team at the Fraunhofer ILT has developed a new process for individual manufacturing of apheres and free-form optics within the scope of the project “Forming and Polishing of Optical Glass Components by Ablation and Remelting with Laser Radiation” (or FoPoLas).

Ablating, Polishing, Correcting

Sebastian Heidrich and his team have been able to produce non-spherical and free-form surfaces with different degrees of curvature out of a quadratic piece of fused silica. In order to do this, they have combined different processing techniques into one process chain: Firstly, a CO2 laser beam heats the material to over 2,230°C, the evaporation temperature of fused silica. This way, the unnecessary material is evaporated selectively and ablated. According to computer generated data, nearly any surface form desired can be produced. In a following step, CO2 laser radiation heats the surface of the component again to near the evaporation temperature so that the viscosity of the uppermost material layer is changed. It becomes fluid and its roughness is reduced on account of the surface tension. The material remains polished once it has cooled. After this laser polishing step, remaining form defects shall be corrected with laser-based precision ablation in the future.

High Economy also for Small Series Production

This process chain is directed primarily at manufacturers of individualized, non-spherical optics. Since the desired surface form is produced based on computer data, it can be changed without extensive retooling. In comparison to conventional manufacturing methods, the use of this process chain could shorten the time it takes to produce optical glass components presumably by a factor of ten. For complex free-form surfaces, this factor can even be much higher. This would mean an enormous reduction in costs and high flexibility for the production of small to medium lot sizes. The process steps can also be used separately, for example, to polish the inside of drill holes, starting from a diameter of several millimeters.

Currently the scientists are optimizing the individual steps of the process chain. Before the process can be applied in the industry, the precision of the ablation process and the surface quality of the polishing process have to be increased. In addition, an appropriate measurement technology has to be developed for form detection, in order to attain suitable optical quality of the manufactured glass components.
On May 11, experts will be presenting the process within the scope of the International Laser Technology Fair AKL’12 in the laser plant park of the Fraunhofer ILT. Interested parties can find further information on this at: www.lasercongress.org.

Contacts at the Fraunhofer ILT

Dipl.-Ing. Sebastian Heidrich
Polishing
Telephone +49 241 8906-645
sebastian.heidrich@ilt.fraunhofer.de

Dr. Edgar Willenborg
Polishing
Telephone +49 241 8906-213
edgar.willenborg@ilt.fraunhofer.de

Fraunhofer Institute for Laser Technology ILT
Steinbachstraße 15
52074 Aachen, Germany
Telephone +49 241 8906-0
Fax +49 241 8906-121

Axel Bauer | Fraunhofer-Institut
Further information:
http://www.ilt.fraunhofer.de

More articles from Process Engineering:

nachricht Design treatment of advanced metals producing better sculpting
08.03.2019 | Purdue University

nachricht Laser Processes for Multi-Functional Composites
18.02.2019 | Fraunhofer-Institut für Lasertechnik ILT

All articles from Process Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New gene potentially involved in metastasis identified

Gene named after Roman goddess Minerva as immune cells get stuck in the fruit fly’s head

Cancers that display a specific combination of sugars, called T-antigen, are more likely to spread through the body and kill a patient. However, what regulates...

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Listening to the quantum vacuum

26.03.2019 | Physics and Astronomy

The struggle for life in the Dead Sea sediments: Necrophagy as a survival mechanism

26.03.2019 | Earth Sciences

Mangroves and their significance for climate protection

26.03.2019 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>