When
measuring a spherical element it is sometimes difficult to rough align the beam,
particularly at non-visible wavelengths. A simple alignment procedure is as
follows:
- Remove the diverger optic. The output beam will be collimated.
- Align and center the collimated beam on the test optic.
- Adjust the tip and tilt of the test optic such that the beam returns into the interferometer aperture. Circular fringes should now appear on the alignment screen.
- Install the diverger lens, being careful not to bump the system and alter the alignment. The system should now be roughly aligned.
- Place an iris or card at the focal point and fine-adjust the alignment, tip/tilt and focus.
