Thermal infrared imaging systems are increasingly vulnerable to the threat of disruption or damage from laser weapons. For laser weapons operating within the waveband of the imager, in-band, the effect is primarily dazzling of the focal plane array. In contrast, for those not in the same waveband, out-of-band, the critical interaction is thermal heating of the outer optical components leading to probable substrate damage. In this article, we analyze the impact of out-of-band high power laser radiation on an infrared telescope operating in the longwave waveband region (LWIR). In particular, we illustrate the stages from coating ablation to subsequent substrate damage. A 1.07 micron continuous-wave fiber laser illuminated the telescope for durations up to a few seconds at a maximum power of approximately one kilowatt. Both visible and LWIR imagers recorded the impact on the outer lens. Our results indicate a predictable chronological sequence of events leading to material damage and heat transfer effects across the substrate as we increased the laser power and duration time.