As mentioned above Photon will have modular design to support LED modules of two different wavelengths. For 400nm modules PQ2N-3FLE-AFC LEDs are used, and  LTPL-C034UVD365 for 365nm modules. PQ2N ones are of CSP type while LTPL ones are wirebonded. UV adhesives should be more sensitive to lower wavelengths, therefore LTPLs should be a better choice. Only question remains; Will higher energy efficiency(irradiated light/W) and lower price of PQ2Ns offset the difference in spectral efficiency?

There are two PCBs with an array of 365nm and 400nm LEDs that connect to a third PCB that interfaces LEDs to the controller module. These prototypes were made on 1.6mm thick FR4 board but final modules will be made on aluminium substrate PCB for best thermal characteristics.