Ferroelectrics field modulation imaging: A useful technique for domain and domain-wall observations

A noncontact optical imaging technique called "ferroelectrics field modulation imaging (FFMI)" is developed to visualize ferroelectric domains and domain walls. The difference image sensing technique with use of area image sensor is utilized to observe the slight modulation of transmitted optical microscope images for ferroelectric films under application of alternating electric fields. We show that the technique allows sensitive, collective and rapid visualization of ferroelectric domains in single-crystal films of hydrogen-bonded organic ferroelectrics. We also investigated further features of ferroelectric domain walls by the technique, regarding the dynamics as well as a tilt in the depth direction of the films.