Lasers are used in microscopy to excite fluorescence in molecules either naturally occurring in biological matter or added by preparation of the sample with special dyes.These dyes are combined with biological molecules forming fluorophores designed to bind to the target of interest in the samples e.g. proteins. The most common method of laser based microscopy is confocal microscopy where a pinhole is used to ensure that only fluorescence coming from the excitation in the focal point reaches the detector this enabling 3d images. LASOS is one of the worldwide leading suppliers of lasers and optical systems for confocal microscopy.
Where the Argon- ion laser was the standard in microscopy for a long time solid state laser are gaining more and more market share. Though the Ar- ion laser is still attractive because of its unbeatable price performance ratio solid state lasers have advantages in size, power consumption and lifetime.
LASOS offers both, gas laser and solid state lasers, giving the customer the choice which technology suits best for the particular instrument. Furthermore, LASOS is able to provide optical components like beam combiners, fiber technology, high precision interfaces and complete lasers systems as plug and play solution.
The variety of different methods in microscopy requires a variety of different laser sources as well which LASOS is able to deliver.
- Large choice of different wavelengths to excite multiple fluorophores
- High modulation contrast to enable imaging and photobleaching with one laser source
- Laser sources with higher power for applications like TIRF
- Narrow spectrum lasers for use of high quality filters to improve fluorescence contrast
- Pulsed lasers for time resolved imaging
Cytometry means to detect specific properties of single cells out of a large volume of cells. The cells can be detected and sorted according to special criteria like the presence of blood cells, cell core material or similar. A common method is Flow Cytometry were cells are marked with bioactive molecules combined with dyes to be excited by a certain wavelength. The cells were suspended in a liquid stream which is narrowed to let only single cells pass. A laser beam hits the cells marked with dyes and sorting is possible depending on the fluorescence signal. To perform a really multiparameter analysis a lot of different dyes are necessary. Hence, the appropriate number of different laser wavelength has to be available. The required laser performance is usually lower than for applications in spectroscopy. Therefore, mostly laser diodes are used to illuminate the cells. However, due to the lack of suitable laser diodes in the green yellow range of the spectrum also diode-pumped solid-state laser are applied. Lasers for Cytometry have to show:
- A large spectrum of available wavelengths
- High power stability
- Low noise
- Long lifetime
Raman Spectroscopy uses the Raman effect which is named after the Indian physicist C.V. Raman who discovered this effect in the year 1928 together with his colleague K.S. Krishnan. It is based on the phenomenon that light which is inelastic scattered by a molecule changes its energy since energy is transferred between photons and the vibration of the molecule. Thus, the scattered photon has a different energy, i.e. frequency than the incoming photon which can be measured. Where in the years after this discovery the use of the Raman effect for measurement purposes seemed to be very much limited due to the high effort to detect this very weak energy transfer today Raman spectroscopy has moved to one of the most applied spectroscopic techniques. This is due to the progress in the instrument design and the availability of useful laser light sources.
To be suitable for Raman spectroscopy the lasers have to show
- high power and frequency stability
- narrow emission bandwidth
- absence of side lines
- high beam quality