Error in previous calculations:

• We did not take into account the effect of cavity input mirror on the coupled light. It would act as a thick concave lens for the coupled light into the cavity.
• We did not take into account the divergence due to refraction at the crystal surface.

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.
• The beam widths should not exceed 4mm in diameter anywhere to ensure small areas of lenses are used.
• Take into account the concave lens due to the input mirror.
• Take into account the refraction due to crystal surface.

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.
• The cavity input mirror is modeled as two refracting surfaces separated by 6.5mm. The first surface is flat while the second has ROC of -25 mm.
• The crystal is modeled as two refracting flat surfaces separated by 20 mm.
• The target beam waist is kept at the center of the crystal with 35.578 um diameter.
• Then save all possible solutions with more than 90% overlap and where lenses are atleast 1.5" away from each other 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