Light & Fluorescence Microscopy
Laser
Light Amplification by Stimulated Emission of Radiation (Laser). As stated, lasers are used because they are an intense coherent monochromatic source of light, capable of being expanded to fill an aperture or focused to a spot. The laser beam is usually linearly polarized. The main drawback in using lasers is that to cover a large excitation range you will need several lasers.
Below is a list of the most commonly used lasers.
- GAS Argon - (453) (476) 488, 494, 514 nm
- Argon-krypton - 488, 568 and 647 nm
- Krypton - 568 and 647 nm
- DIODE 640 nm red, 480 nm blue,440 nm blue/violet, 405 nm violet
- Helium-neon - 633 nm
- Green HeNe - 544 nm
- Frequency doubled DPSS 488 nm blue, 532 nm green, 561 nm yellow/green
- Multiphoton tunable lasers. 700 to 1040 nm.
However a single laser line may not optimally excite your molecule. The table below gives you an example of which laser lines to use and the efficiency of excitation for different probes.
Another thing to note is that each laser line is of different strengths. Therefore if you have similar intensities of probe you may use 10% of one line and 5% of another to achieve the same emission strength.
