Simple characterisation of a deformable mirror inside a high numerical aperture microscope using phase diversity.

Area of Science:

• Microscopy
• Optical Physics
• Wavefront Sensing

Background:

• Characterizing optical elements like deformable mirrors is crucial for advanced microscopy.
• Existing wavefront sensing methods can be complex and require setup modifications.

Purpose of the Study:

• To present a simple and versatile scheme for characterizing amplitude and phase modulation by active elements in a high numerical aperture (NA) microscope pupil plane.
• To enable accurate measurement of deformable mirror influence functions.

Main Methods:

• A mirror was placed near the objective's focal plane to record reflected focal spot images.
• An iterative electric field retrieval algorithm was used to obtain mirror influence functions.
• The method was validated by comparing results with a Shack-Hartmann wavefront sensor.

Main Results:

• Reliable measurements of mirror actuator influence functions in the pupil plane were obtained.
• The proposed method achieved comparable precision to a Shack-Hartmann sensor.
• The technique demonstrated versatility across different objectives and compatibility with pulsed sources.

Conclusions:

• The presented scheme offers a simple, versatile, and space-efficient method for characterizing active optical elements in microscopy.
• It provides a valuable alternative to direct wavefront sensors, especially for multiphoton microscopy and various objective types.