Photon cannons are particle cannons used by the "Fleet of Fog" as the replacement for standard cannons and AA auto-cannons. Sometimes, photon cannons are referred to as the Laser Oscillation System.
Despite their name, photon cannons behave more like particle cannons, because photon-based weaponry (lasers, masers, etc.) do not cause explosions on the scale that is shown in the series. It is possible that these cannons, much like the Super-Graviton Cannon, use gravitational waves condensed into a narrow beam to deal damage.
Photon cannons are much less powerful than the Super-Graviton Cannon. While they still can deal a lot of damage to human-made structures or vessels, even moderately-powerful Wave-Force armor can take many hits from high-caliber photon cannons before reaching saturation.Depending on their purpose, photon cannons can fire very quickly with a low charge per shot (for example in anti-air and anti-missile defense systems, where the density of fire is more important) or fire more powerful shots, with a longer recharge period (for example for us as cannons on the main turrets of large battleships). In some cases, miniature photon cannons can be used as anti-personnel weaponry, in the case that the ship is boarded by enemies. In such circumstances, the power of each shot can be lowered to non-lethal levels against human targets.
Photon cannons appear to be also capable of firing conventional projectiles. However, the reasoning behind this unknown.