LasDif

Background

Until now, measuring the duration of ultrashort laser pulses has only been possible with costly autocorrelators. Developing a compact, DOE-based measurement system aims to reduce the cost of such measurements and minimise the size of the system. For many ultrashort pulse laser systems already established in manufacturing, cost reduction is a key factor.

Project objectives

• Building a measurement system for determining the duration of ultrashort laser pulses
• Developing the necessary theoretical foundations
• Simulating the required diffractive optical elements (DOE)
• Realising the DOE by microstructuring
• Combining the DOE with a detector chip into a measurement system
• Evaluating the system in practice

Setup and fabrication

The laser beam hits the DOE, whose diffraction pattern is recorded by a camera or detector chip. Depending on the pulse duration, the diffraction orders differ, from which the pulse duration can be determined. The DOE is fabricated lithographically: a glass substrate with 100 nm chromium and photoresist is exposed and developed, the chromium is wet-chemically structured, the resist is removed, the structure is transferred into the glass by RIE-ICP etching, and the chromium is then removed wet-chemically.

Project partners

• Darmstadt University of Applied Sciences (h_da), Department of Mathematics and Natural Sciences: joint project partner (Prof. Dr. Matthias Will)
• Spectra-Physics
• TOPAG Lasertechnik GmbH
• PRIMES GmbH
• Optence e.V.

Funding

LasDif is a joint R&D project in the Hessian funding programme “Forschung für die Praxis” of the universities of applied sciences, funded by the Hessian Ministry of Higher Education, Research and the Arts.