The technical committee on light application and visual science (TC-LAV) has been surveying fields of application of optical engineering and visual science, covering medical science, devices for visual information processing, light sources from terahertz wave to extreme ultraviolet, advanced lithography, and so on. This article introduces two topics from recent research activities. They are optical control of thick resist pattern profiles, and characteristics of random errors in intensity and phase measured with THz time-domain spectroscopy.