Consider a single mode Gaussian beam entering a 0.75 NA objective. I made measurements of beam's FWHM around the focus. It looked like before the focus, the beam converges according to NA=0.75. But after the focus, NA is somewhat larger - I saw this in 3 attempts. Is this normal? NA=0.75 is not associated with a single mode beam usually.
Adrien Mau
Could you try with a collimated flat-field beam ? Maybe it's just the gaussian divergence of the laser showing up but it's strange it only appears after focus.. What is quantitatively the NA variation after focus ?
0 votes
0 thanks
- Badges
- Science topic
More Elena Renzhiglova's questions See All
Similar questions and discussions