A liquid-containing heat filter for use with a high-intensity light, said liquid-containing heat filter comprising a substantially hollow reservoir for receiving heat-filtering liquid therein, the reservoir comprising a first optically transparent member, a second optically transparent member, and a peripheral frame for receiving and retaining said first optically transparent member and said second optically transparent member, heat-filtering liquid disposed in said substantially hollow reservoir, and a first resiliently deformable member interposed in trapped relation between the first optically transparent member and a first portion of said peripheral frame, wherein, in use, when the heat-filtering liquid in the reservoir raises in temperature due to the heating effect of the high-intensity light, the first resiliently deformable member is compressed to thereby allow the outward movement of the first optically transparent member due to expansion of the heat-filtering liquid.
