High-resolution wavefront correction in multiphoton microscopy

A system for making wavefront corrections for use in multiphoton microscopy has been constructed. Corrections are made using a high-resolution nematic liquid crystal device which has a phase stroke of 2 pi. The device has a design wavelength of 1064 nm. A simple way for setting the device up for lower wavelengths (here 800 nm) is presented. It was found that the device has an undesired zero-order diffraction component of 30%. A scheme for filtering this portion out is presented and it was demonstrated that this can eliminate the component completely. The device was used to optically simulate a thin lens with a specified focal length, which was found to match within error bounds. Finally the modulator was used to compensate for a mechanical defocus that was applied intentionally.