Beam Optics
Purity, and the lens that raises it.
A 
Prismarine Laser Relay passes a beam on in a straight line and a 
Laser Junction turns, merges and splits it, and neither changes its purity (see Moving Laser Power). Recipes check purity before they run, so plan your source around the purity the machine at the end needs.
Purity
Purity is set by the source. Merging beams lowers it a little, and a Focusing Lens raises it.
| Source | Purity |
|---|---|
 Aquatic Catalyst on Prismarine Shards |
0.4 |
| Aquatic Catalyst on Prismarine Crystals | 0.8 |
| Aquatic Catalyst on Prismarine Crystal Shards | 1.2 |
 Bacterial Fuel Cell |
up to 2.5 |
 Prismarine Crystal, hit from the side |
3.0 |
Each Budding Prismarine block touching an Aquatic Catalyst adds 0.1 to its beam's purity, up to 2.0. See Laser Power.
The machines in this section need these purities:
| Output | Machine | Purity |
|---|---|---|
| Flawless Prismarine Crystal | Abyssal Pressure Forge | 2.0 |
| Atlantic Gold Ingot | Abyssal Pressure Forge | 2.0 |
| Deep Steel Plating | Abyssal Pressure Forge | 2.5 |
| Resonant Shard | Resonance Chamber | 3.0 |
| Prismarine Crystal Seed | Resonance Chamber | 3.0 |
When two or more beams feed the same block, their power adds up and their purity stays close to the purest beam. The result is the highest purity minus a quarter of the gap between it and the average of all of them (beamMergePurityDrop), so a 3.0 beam merged with a 0 beam comes out at about 2.6.
Focusing Lens
Raises the purity of a beam that passes straight through it by 0.5 (lensPurityBonus), up to a limit of 2.0. Place it while looking the way the beam travels: the face toward you takes the beam in, the far face sends it on, up to 16 blocks (laserDistance). Power passes through unchanged, and it can be placed under water.
The lens only adds purity to a beam that already has some, so put it after a working source. A beam at 1.8 comes out at 2.0, and a beam already at 2.0 or higher passes through unchanged, so a row of lenses tops out at 2.0. Run two in a row to lift a Prismarine Crystal Shard catalyst (1.2) to the 2.0 the Pressure Forge needs for Flawless Prismarine Crystals. For 2.5 and 3.0, use a Bacterial Fuel Cell or a Prismarine Crystal as the source.
