Low-cost LED UV source with power and wavelength variable emission

Ultraviolet sources are of great interest to many research areas and their applications. From UV disinfection to UV spectroscopy, UV sources with different emission power and wavelengths are needed. Commercially available UV lamps may be arc-discharge, incandescent, or fluorescent lamps; however, their cost may reach thousands of US dollars. Furthermore, they do not always fulfill the needs of the application. For example, arc-discharge or incandescent lamps have a wide emission spectrum forcing the use of different expensive filters for the applications needing a narrower emission bandwidth. Moreover, high emission power could not be desirable to biomedical research and applications due to associated damage with ultraviolet light. LEDs may solve the aforementioned issues; however, a single LED is clearly not a solution if a broad spectrum is needed. In this work, we present the design and characterization of a homemade LED-based UV source with variable emission in terms of power and wavelength. The source is constructed with five different LEDs in the UVA interval, covering an spectral range from 355 to 395 nm. An Arduino unit controls the source, allowing the user to select the emission of only one or the sum of a set of LEDs with desired wavelengths, extending the bandwidth. Finally, we present an analysis of the advantages and disadvantages of the proposed source for different optical applications.