I have three collimated optical beams with 1cm separation between the adjacent one. I want to shift one of the three beam laterally so that it goes closer towards or farther away from the adjacent beam by micrometer accuracy.
Dear Sreeprasad
If you are not worried about relative phases and can tolerate a number of very weak secondary beams, perhaps the simplest way is to insert a tilted parallel glass plate into the beam you want to translate. The translation of the main transmitted beam will be Theta*T*(n-1)/n, where n is the refractive index of the glass plate, T is its thickness and Theta is the tilt of the plate's normal relative to the beam propagation direction (in radians). A 1 mm thick glass slide at 5 degrees will result in a shift on order of 50 microns. The main drawback from this method is that more than one beam is transmitted due to the multiple reflections at the glass surface, however the main transmitted beam will be several hundred times more intense than the strongest secondary beam.
Good luck
Do you have a diagram of your optical arrangement?
I am assuming that the three beams are parallel?
Where do your beam originate before they are parallel?
If they come directly from separate sources, an obvious modification would be to mount the source on a translator.
If they are brought parallel by separate mirrors for example, adjusting the position of the mirror will translate the beam, or adjusting its angle if located at the focal plane of a lens will also translate the beam without changing its angle.
Is this something you wish to perform dynamically or just set once and leave it?
Again, some more information about your setup and application would be helpful in giving an informed answer
Dear Sreeprasad
If you are not worried about relative phases and can tolerate a number of very weak secondary beams, perhaps the simplest way is to insert a tilted parallel glass plate into the beam you want to translate. The translation of the main transmitted beam will be Theta*T*(n-1)/n, where n is the refractive index of the glass plate, T is its thickness and Theta is the tilt of the plate's normal relative to the beam propagation direction (in radians). A 1 mm thick glass slide at 5 degrees will result in a shift on order of 50 microns. The main drawback from this method is that more than one beam is transmitted due to the multiple reflections at the glass surface, however the main transmitted beam will be several hundred times more intense than the strongest secondary beam.
Good luck
Thank you so much Prof. Michael Belsley for this suggestion.
Thank you Prof. Alexander Malm for the reply. Actually, the setup we are building is for surface topography applications. We are focusing mostly in profilometry side now. So, it structures are static only.
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