The standard version of our KLM modules ships with an aspheric acrylic lens – sufficient for stable indoor temperatures. With strongly fluctuating operating temperatures (more than ±5 °C variation) the acrylic lens can shift focus – beam width changes and sharpness suffers. The optional three-lens glass collimator is significantly more temperature-stable: glass barely expands, so the focus stays constant. Recommended for: outdoor mounting, unheated halls, machines with large temperature swings (welding, sawmills in summer/winter) and applications needing high repeat accuracy over long periods.