Hamamatsu Photonics K.K. has developed a LCOS-SLM (liquid-crystal-on-silicon spatial light modulator) with a heat sink that offering lightfast performance for applications such as laser marking with 100W class high-power lasers. The new LCOS-SLM is optimised to minimise the influence from temperature changes, in which an optimised mirror design and a heat sink are introduced. As a result, the power handling capability has been improved from 40 W/cm2 to 210 W/cm2 or more. The new LCOS-SLM is expected to be used for laser processing applications such as laser marking with high-power lasers.