Project: Process control for the femtosecond laser surface modification by high resolution imaging spectroscopy

Analysis of demands of SMEs involved in modern Hi-Tec Technologies has shown great market potential for diagnostic systems able to monitor the CO process parameters. Unfortunately, both the diagnostic equipment and process control methods are not developed for sophisticated industrial processes, such as laser femtosecond material treatment, micro fabrication techniques, etc._x000D_IfU GmbH (the CO proposal P) has developed and patented an original Acousto-Optical Filter (AOF) /1/. The CO feature of spectrometer based on AOF is fast random wavelength access, fast registration time and the possibility of registration of 2-dimensional spectral images for selected wavelengths in principle. A novel Acousto-Optic Spectrometer (AOS) produced by IfU GmbH was successfully applied for true 2-dimensional (2D) spatially and phase resolved spectroscopic measurements of various plasma processes. The spatial intensity distribution of each emission line may depend strongly from the plasma process conditions /2/ and can be applied for on-line process control._x000D_The further development of this unique measurement system regarding a short-time spectral resolution videospectrometer (time resolution 5ns, wavelength resolution 0.5nm, 200 x 200 pixels) would result in completely new applications, in particular the analysis of the CO features of laser femtosecond material treatment and micro fabrication techniques. The P in Lithuania, Altechna Ltd. has developed new femtosecond laser submicron precision micro-nano fabrication system AltSCA(R). The CO common issue or problem of fabrication processes is necessity to analyze a near surface erosion/plasma plume cloud which is needed to optimize technological parameters and to reach desired product quality. Modern femtosecond lasers operate in quasi continuous mode (frequency 70-100 MHz) and life-time of erosion/plasma plume much longer (nanosecond range) than femtosecond pulse duration. Preliminary analysis show that 5ns time resolution could be enough for effective process control of femtosecond material treatment. _x000D_Therefore Altechna Ltd will develop a high precision, nano-second controlled laser treatment technology and the corresponding equipment. IfU GmbH will develop a fast, high resolution (temporally and wavelength-wise) imaging spectroscopy for the insitu process analysis and control. The Hungarian P FKK will develop a system (hardware, electronics) for the integration of components in automation lines._x000D_The present project concentrates on these three points with the knowhow of the Ps:_x000D_- IfU GmbH, Germany – CO P, research performing SME, developer and manufacturer of diagnostic systems based on AOF patent_x000D_- Altechna Ltd, Lithuania – P, research performing SME, specialized in laser technologies and laser induced breakdown spectroscopy (LIBS)_x000D_- FKK, Hungary – P, research performing SME specialized in industrial process control and automation._x000D_Based on that knowhow a technology for high precision, fully automated insitu controlled femtosecond laser surface modification should be developed._x000D_In particular the following tasks have to be realized therefore:_x000D_IfU GmbH_x000D_- To visualize fast laser processes with the AO-videospectrometer it is necessary to move the system control and data acquisition into a nanosecond scale. An image intensifier with a nanosecond gate function will be used for realisation and a nanosecond synchronisation of AOF and camera system incl. the image intensifier is needed. _x000D_- To realize a nanosecond time resolution a small time gate to shutter the image intensifier for collecting data is moved around the fast laser pulse event using a nanosecond synch signal. The expected results will be multidimensional structures generated in microseconds. _x000D_Altechna Ltd_x000D_- Analysis of the CO features of micro fabrication techniques, laser femtosecond material treatment, surface patterning and plasma materials treatment; analyzing of near surface erosion/plasma plume to optimize technological parameters and to reach desired product quality._x000D_- Development of prototype of industrial femtosecond laser treatment system controlled by imaging spectroscopy to be applied in modern Hi-Tec industrial technologies._x000D_FKK_x000D_- Integration of the developed AOS with industrial equipment: design of fibre coupling unit; development of software for joint operation and synchronization with industrial equipment; refinement of electronic design for data recording; design of cases to protect against noises._x000D__x000D_/1/ Patent 197 13 254 “Acousto-optical filter”, patent owner: IfU GmbH;_x000D_/2/ „True 2D Imaging Time Resolved Optical Emission Spectroscopy in a HPPMS Pulse Discharge from Titanium Target“, T. Wallendorf, S. Marke, R. Bandorf, P. Giesel, M. Vergöhl, lecture at Society of Vacuum Coaters Conference (SVC 2007).

Acronym FEMSPEC (Reference Number: 4296)
Duration 01/10/2008 - 30/09/2011
Project Topic For the first time fast imaging acousto-optical spectrometer will be developed for industrial high precision femtosecond laser treatment of nanostructures. It will be adapted with industrial equipment, process features will be studied and process control algorithms will be developed.
Project Results
(after finalisation)
During the project we investigate the possibility of monitoring a plasma in a pulsed femtosecond laser ablation process with a emission spectrometer. In the first step we used our acousto optical spectrometer AOS for the measurements. We were able to detect single wavelengths intensities of the spectra with a time resolution and reaction time of nearly 50 ms. In the measurement results two CO problems were significantly. First the small intensity of the plasma emission and second the need of a higher time resolution regarding a lower reaction time. Because of these results we developed a measuring platform with 2 optical non wavelength tunable sensors for two different wavelengths with a reaction time of nearly 50 µs. With this platform it is possible to monitor such laser induced plasmas with low intensity.
Network Eurostars
Call Eurostars Cut-Off 1

Project partner

Number Name Role Country
3 Invention and Research Center Services Ltd. Partner Hungary
3 IfU GmbH Coordinator Germany
3 Altechna Co.Ltd. Partner Lithuania