Abstract: The optical window is useful in laser-initiated explosive devices. It includes a solid transparent block of high temperature-resistant material such as glass, quartz, corundum, cubic zirconia or the like having two opposed light input and light output surfaces, one or both of which bear ablative mirror coatings of metal or the like, preferably aluminum, silver or gold, which can be vaporized by a laser beam. Preferably, the coatings are covered by a protective ablative film which resists scratching or the like. Such may be, for example, silicon monoxide. The coatings reflect incident light so as to prevent inadvertent initiation of explosive situated behind or downstream of the window in an explosive device. Preferably, the block is cylindrical with a curved light-focusing input surface which reduces the intensity which the laser beam trained through the window has to have in order to vaporize the mirror coatings and set off the explosive.