Lasers | Lasers
Key Words: phototoxicity, AOTF, fluorescence, AOM, CLEM, Illumination
Definition:A device that produces an intense, coherent, directional beam of light
TECHNOLOGY:
There are various types of lasers, for example, gas (e.g. argon), solid state (e.g. ruby), molecular (e.g. eximer) and free electron, but they operate on similar principles. When the medium is excited by external energy (heat, light, electricity) electrons in the atoms are excited to a higher energy level. When the electrons relax to the ground stare a photon is emitted. The wavelength of the photon is determined by the electron transition. The photons interact with excited electrons to stimulate the release of more and more photons. The stimulated emission process creates photons that are 'in phase' with the reflected or 'stimulating' photons and are of the same wavelength. Only light that passes along the length of the tube is reflected to produce an intense beam of monochromatic light that is coherent, mono-directional and passes through the partially reflective mirror to create the laser beam. Light may be delivered in a continuous beam or in 'pulsed' bursts of light. The power and target area for laser illumination can be modified with AOM, AOTF or CLEM technology.
APPLICATIONS:
Lasers are an important tool in a variety of microscope imaging techniques such as laser tweezers, laser scanning confocal microscopy and associated fluorescent techniques such as FRET, FRAP, FLIP, FLIM and TIRF. They may also be used in some widefield fluorescence applications where high intensity light is required to excite fluorophores. The choice of laser(s) will depend on the imaging application and the fluorescent probes used. Continuous wave lasers are generally used in confocal imaging while mode-locked pulsed lasers are used for multiphoton microscopy.
MICROSCOPE CONFIGURATION:
The C1-Plus confocal system accommodates directly modulated 408nm, 440nm and 638nm diode lasers, as well as a new diode pumped solid-state laser at 561nm. Continuously variable attenuation for each laser line, either manually or through EZC1 software by AOM, improves live cell imaging and FRAP and FRET applications. The EX-type three laser table can accommodate all of the new lasers plus a filter exchanger for selecting either the 488nm or 514nm line of a multiline Argon ion laser.
The C1Si confocal system accommodates a three laser unit with AOM control or direct electronic modulation of laser intensity. Lasers: 488nm single line and 4-line multiline Argon ion lasers, 405nm, 440nm, and 638nm directly modulated diode lasers, 561nm diode pumped solid state (DPSS), and 488nm solid state.
LiveScan Sweptfield confocal system: Air cooled Argon ion 488 and 514nm. Air cooled Krypton-Argon 488, 514, 568, and 647nm. Optional laser 45mW diode 442nm. Optional dual emission fibre available.
RECOMMENDED SYSTEM:
Consult you local Nikon representative.
LINKS:
Laser safety: [microscopyu]
