Continuous wave(CW)and pulse width modulation(PWM)are two technologies to control the output of a UV LED light source.Continuous wave radiation system typically provides better curing results primarily due to its stable UV output.Thus it is preferred for most applications especially those requires better curing quality.Traditionally,PWM technology is only used in LED lighting applications to control the illumination level.For curing applications,study in PWM system shows using such system can help reduce the substrate temperature,which is beneficial to the process on heat sensitive materials.Low frequency low irradiance LED system also seems to be more effective in certain disinfection and sterilization applications.This article discusses the differences between the two technologies,the advantages of each,and their respective applications.