Hello researchers,
I am constructing a PrismTIRF. I have a problem defining focus and detecting signals with labeled DNA (the bead sample works fine). I have looked for some possible solutions, yet have not been successful so far.
I wonder if the polarization type (p-polarized or s-polarized) of the laser can also cause this problem. Because I have read from some forums that a p-polarized laser can enhance the evanescent generation. My laser has a polarization ratio 100:1. Please share some experience with me.
Thank you.
Lazerin polarizasyon oranı doğru. Lazer polarizasyon tipi p veya s olabilir. Odak tanımlama ve DNA tespitinde (boncuk örneği iki taraf birbirine simetrik olmalı. P tipi polarizasyonla yapılırsa bu simetrik olay olur.Yine boncuklar birbirine simetrik iki tarafa merdiven şeklinde dizilirse birbirini tamamlar ve arada bir DNA bandı oluşur. P tipi polarizasyon kaynağı yeterince güçlü olmalı. Boncuklar arasındaki mesafe her zaman korunmalı. Lazer kaynağının güç, verim ve iletkenlik durumları yeterli seviyede olmalı.
The state of a laser's polarization is determined by several anisotropic mechanisms of either the laser gain media or the resonator. "Anisotropic" refers to properties whose values vary in different directions. A laser gain medium may be polarization-dependent, as is the case with some anisotropic laser crystals and semiconductor optical amplifiers. Inside this medium, emission is stimulated by incoming pump photons. Stimulated emission photons will be emitted in the same polarization state as that of the pump photons. With the absence of polarization-selection optics, such as polarizers and waveplates (also called retarders), light would be unpolarized and unsuitable for certain applications. In addition, losses in the resonator, from the inclusion of a Brewster plate or a slight misalignment of any other optical components involved, can be responsible for changes in polarized laser emissions.
The polarization extinction ratio (PER)(PER) can be used to determine the degree of polarization after propagation through a device or system, such as a laser cavity. It is the ratio of the optical power in the principal polarization mode to the orthogonal polarization mode, where each of these modes are perpendicular to each other. These polarizations are usually called TE (transverse electric) and TM (transverse magnetic).
The polarization does not affect the strength or depth of the evanescent wave, but it does directly determine the polarization of the evanescent wave. See, for example, this animation.
https://www.olympus-lifescience.com/de/microscope-resource/primer/java/tirf/evaintensity/
The polarization of the evanescent wave can have a strong effect on how well the light interacts with the sample, particularly if the sample is ordered and the polarizability differs in different directions. However, even in an isotropic medium the existence of the interface itself breaks symmetry and changes the response depending on polarization.
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