Third-generation night-vision systems developed in the late 1980s maintain the MCP from Gen II, but now use a photocathode made with gallium arsenide, which further improves image resolution. In addition, the MCP is coated with an ion barrier film for increased tube life. However, the ion barrier causes fewer electrons to pass through, diminishing the improvement expected from the gallium-arsenide photocathode. Because of the ion barrier, the "halo" effect around bright spots or light sources is larger too. The light amplification is also improved to around –. Power consumption is higher than in GEN II tubes.