The PCR-3 operates on an unusual energy principle: rather than generating its own destructive output, it catalyzes a photovoltaic cascade reaction in surfaces it strikes. A precisely modulated ultraviolet primer beam is fired first, lasting approximately 12 milliseconds, which seeds the target surface with a resonant photoelectric charge. A second, high-intensity visible-spectrum pulse follows immediately, triggering an explosive release of that stored charge across the target's surface area. The result is a directed electrical detonation that originates from the target itself rather than the weapon — armor and shielding that would normally absorb or deflect an incoming energy beam instead become the source of the discharge.

Helix Biosystems developed the PCR-3 as part of a research program into photovoltaic energy harvesting, and the weapon represents a militarized accident — a researcher demonstrated that the cascade reaction could be induced in organic tissue, which has its own weak photovoltaic properties due to melanin and porphyrin compounds in skin and muscle. On living targets, the electrical detonation produces severe burns and cardiac disruption from the inside out. On synthetic materials — particularly the photoreactive polymers used in common body armor — the effect is even more dramatic, causing catastrophic structural failure of the armor itself.

The Tithe's form is elegant and slender, a long-barreled rifle with a dual-emitter muzzle that houses both the UV primer and the visible-spectrum trigger. The barrel is unusually cool to the touch even after sustained use, as the weapon itself generates relatively little waste heat — the energy is deposited in the target. This gives the PCR-3 a deceptively benign appearance that has made it a favorite of collectors and a headache for customs enforcement.