We found that the ferroelectric coercive field of LiTaO3, both in forward and reverse directions, can be increased in large amount by high power multiline argon laser illumination. This phenomenon is especially profound when the coercive field measurement is performed closer in time to the previous domain inversion operation. We also demonstrated that the domain in lithium‐tantalate crystal can be patterned in accordance with the argon laser light distribution on the crystal plate surface. ©1996 American Institute of Physics.