Errors in the previous analysis

• Previously, we wrongly assumed. that the reflected light from the cavity would be as if a reflection is happening from a flat mirror. It actually follows the same paths as incident light in the reflection path.
• Lens were restricted to non-overlapping regions but that meant that solutions where lens are close to each other can only happen near the boundaries of these regions. Removing this condition widens the search for a good solution.
• We collimated the beam to near 0.5 mm radius with a 229.1 mm focal length lens at 67" from laser head and put faraday isolator in front. So now the problem only remained to match the mode after this point to the cavity mode.

Goals and restrictions:

• Use the fewest lenses as possible after having used a fixed lens at 67" point before the faraday isolator.
• Choose a lens from a list of focal lengths available in west bridge labs.
• Find the best overlap with the target beam of 18 um at the cavity waist with the most sensitivity with respect to lens positions.
• The lens should not be closer than 1.5 inches from each other or to the EOM mount or cavity edge.
• The beam widths should not exceed 4mm in diameter anywhere to ensure small areas of lenses are used.

Analysis & Results

• CavityLens.m is run to try all possible lens combinations for 1-lens or 2-lens solutions using ../20201222_BeamProfileNeatEOM/SeedBeam.mat as the seed beam.
• CavityLens3.m and other versions of it are run to try all possible lens combinations for 3-lens solutions using ../20201222_BeamProfileNeatEOM/SeedBeam.mat as the seed beam.
• Then save all possible solutions with more than 90% overlap and where lenses are atleast 1.5" away from each other and the cavity in AllPossibleSolutionsAbove90.mat using findPossibleSolutions.m.
• findBestSolutions.m increases the overlap threshold to 0.995, allows maximum beam radius of 2mm anywhere and plots the best solutions in order of positional sensitivity of the lens. These are stored in BestSolutions.mat.

Analysis & Data