UFD is abbreviation for Ultra Flat Dispersion.
LASER Diode has monochromatic wavelength distribution.
LED has wide wavelength distribution compared with LD.
Conventional spotsize of light on the recording track has been described as a function of Wavelength.
with UFT, spotsize of light on the recording track might be corrected as follows.
Media and Optical system of Ultra Flat Dispersion should be given for UV LED sources.