lasers

Light Sources

The Centre for Advanced Laser Applications accommodates a worldwide unique laser technology. The two high tech laser sources ATLAS-3000 (Advanced Ti:Sapphire Laser 3000 Terawatt) and PFS-pro (Petawatt Field Synthesizer), as well as the world’s first commercially distributed Compact Light Source (MuCLS), a combination of a compact electron accelerator and lasers for the generation of X-rays, are domiciled in CALA. The scientific infrastructure basically consists of the laser sources and related experimental areas. Whereas at MuCLS the X-ray source is directly connected with the experimental area, ATLAS and PFS-pro are located spatially separated from the experimental areas. The connection to the experiments is provided by a vacuum system of pipes through which the laser light is guided (LBD, Laser Beam Delivery).

ATLAS and PFS-pro are femtosecond short-pulse lasers (a femtosecond is a millionth of a billionth of a second, 10-15 seconds). Its pulsed light has high frequency and extreme intensities. Thereby a flash consists of various energy-rich light particles (photons). Laser light in this shape is able to do an enormous amount of work. The aim is to exert influence on charged particles such as electrons or protons (charged nuclear particles). As an electromagnetic wave light has an electric and a magnetic field. Electrons and protons react to these fields. A strong pulse of light hits electrons out of atoms and accelerates them almost up to the speed of light. Such laser-driven, free electrons produce for their part X-rays when the particles are decelerated or accelerated. This kind of X-rays can be used for the recognition of finest structures, such as tumors at an early stage. Protons can “only” be accelerated up to roughly 10-20 percent of light speed through the light of our lasers, but with this they possess sufficient energy for the use in radiotherapy of tumors.

The already existing light-driven technology for particle acceleration will be enhanced at CALA, up to the even more efficient generation of X- and proton rays for the usage in medicine. Similarly the further development of a laser-based femtosecond infrared spectroscopy for high sensitive detection of cancer markers in blood and air is planned (BIRD, Broadband Infrared Radiation Diagnostics).

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Advanced Titanium-Sapphire Laser (ATLAS)

The high-intensity laser ATLAS serves as one of two main pillars of the laser infrastructure of CALA, and the central unit for research on compact laser-driven particle and radiation sources. ATLAS will supply laser pulses at a world-class performance level of 2.5 – 3 PW, at a repetition rate of 1 Hz. The ATLAS facility consists of the existing ATLAS-300 laser (which will continue to be developed at CALA) as the front end to the 90-J amplifier ATLAS-3000 from the company Thales Optronique, and an independently developed pulse compressor. The ATLAS beam will be available for physical and biomedical experiments to be carried out at CALA for which high pulse performance is required. Specifically, these are:

  • The compact ion source LION
  • The electron source ETTF
  • The undulator radiation source LUX
  • The high-field physics beamline HF

Project Coordination: Prof. Dr. Stefan Karsch

  • Peak Power
    2.5 - 3 PW
  • Pulse Duration
    20 fs
  • Pulse Energy
    60 J
  • Repetition Rate
    1 Hz

Petawatt Field Synthesizer (PFS-pro)

The Petawatt Field Synthesizer (PFS-pro) is a laser system that is developed within the scope of the CALA project and on the basis of world-leading LMU laser technologies. After its gradually completion in 2017-2018, the PFS-pro is going to provide highly-intense, ultra-short light pulses with worldwide unique parameters for physical and biomedical experiments out of overall three output channels for several experimental stations at CALA. These are firstly the X-ray source SPECTRE, with which the notified high photon energy (50-200 keV) shall be used for medical imaging, and on the other hand a HHG-beam line with which the attosecond X-ray spectroscopy (above all for questioning of biomedical relevance) is performed. Furthermore, it is planned to serve as well BIRD experimental areas with a broadband infrared output channel.

Project Coordination: Dr. Thomas Nubbemeyer

  • Average Power
    1 kW
  • Spectral Bandwidth
    100 nm
  • Repetition Rate
    10 kHz

Coherent Infrared Light Source (InfraLight)

Besides the two laser systems ATLAS and PFS-pro the physicists from CALA develop another laser system for infrared spectroscopy in the framework of BIRD. The basis of this spectrometer is a worldwide unique light source for generating ultrashort pulses, an infrared ultrashort pulse – laser exclusively developed by the Ludwig-Maximilians University.

The spectrometer now already connects various characteristics required for BIRD experiments. The coherent light source in use is brilliant. That means that a great many photons are temporally and spatially packed to individual, ultrashort and high-performing impulses. In this process the light covers almost the entire range of medium infrared and ranges from 6,8 to 18 micrometers of wavelength. The pulses are emitted periodically and repeat a 100 million times per second. Every laser pulse lasts roughly 66 femtoseconds.

The further development of this CALA laser system includes the transmission of pulses through the entire infrared range of light. Infrared light is an excellent helper when it comes to track down single molecules. Molecules react very individual to infrared light and absorb, depending on their condition, different wavelengths of the spectrum. With the help of the resulting absorption-fingerprints it is possible to recognize single molecules among billion others. With the help of the laser the researchers will start looking for molecular disease indicators in breathing air and blood (BIRD-projekt).

Project Coordination: Dr. Oleg Pronin, Dr. Ioachim Pupeza

  • Average Power
    > 1 W
  • Spectral Bandwidth
    2.5 - 25 μm
  • Repetition Rate
    50 MHz

Laser Beam Delivery (LBD)

The system connects the laser systems ATLAS and PFS-pro with the experimental stations LION, LUX, ETTF, SPECTRE and HF. The LBD establishes the vacuum connection and accommodates the laser mirrors that conduct the laser pulses to the experimental station.

The LBD-vacuum-system consists of DN320 pipes that run in a right angle along the buildings main direction. The laser-sided interface is the respective compressor chamber. At the corner points larger vacuum chambers are installed. Every mirror is fixed in a vacuum-compatible optomechanics. Due to two motorized screws the mirror can be tilted into both spatial axis in order to hit the following mirror centrically. A camera displays the scattered light and the mirror to enable a manual fine adjustment. At the branches of the LBD switch-boxes or bypass-boxes are implemented. They accommodate the laser mirrors and allow a motorized motion to steer the laser pulses into the particular experimental station.

Project Coordination: Prof. Dr. Jörg Schreiber

Munich Compact Light Source (MuCLS)

The Munich Compact Light Source (MuCLS) creates X-rays through the collision of high-energy electrons with low-energy photons from an infrared laser. Like balls in billiard game, the photons collide with the electrons, absorbing some of their energy and thereby reaching the X-ray range. These collisions can be repeated 65 million times per second as the electrons circulate in a storage ring, and the photons revolve in a resonator. The volume of collisions, and thus the size of the X-ray source, is approximately 45-thousandths of a millimeter: about half the width of a human hair. These X-rays are monochromatic, with an energy bandwidth of only ΔE/E = 3%. Their energy can be varied between 15 and 35 keV. The X-rays generated form a narrow, conical beam that can easily be guided into two experimental stations approximately 3m and 16m downstream.

The above-described characteristics of the X-rays created by the MuCLS make it an ideal tool for use in both a pre-clinical medical imaging environment, and in materials science research. In addition to conventional X-ray absorption, used for example to distinguish bone from soft tissue, the X-rays from the MuCLS are also ideally suited to the newer applications of phase-contrast and dark-field X-ray imaging. Using phase-contrast imaging it is possible, for example, to increase the visibility of tumors surrounded by soft tissue, or of narrowed blood vessels. Dark-field imaging is sensitive enough to detect small structures such as pulmonary alveoli, and can also detect cracks in carbon fiber or failure in plastic components.

The low beam power, broad energy spectrum and large source size of conventional X-ray systems (such as those found in doctor’s practices or in clinics) are insufficient for many applications. Synchrotron radiation sources, however, can be impractical, being costly, having the scale of a soccer arena, and with time for measurements not easily obtainable. The Munich Compact Light Source thus bridges a gap.

 

Project Coordination: Prof. Dr. Franz Pfeiffer, Dr. Klaus Achterhold

  • Primary Beam
    electron accelerator + IR-laser
  • Secondary Beam
    monochromatic X-rays
  • Main Motivation
    biomedical imaging
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