In this paper will be described the analytical expressions which will provide the damage thresholds of infrared and visible imaging systems when subjected to high power continuous wave and repetitive pulsed laser devices. The primary optical components that comprise a system are generally optical substrates that have vapor deposited reflective metal films or are diamond turned metallic substrates to maximize reflectivity. Additionally, one will find optical thin films used to enhance reflectivity and transmission through the optical train. For those systems that are designed for the infrared, the materials that have the best reflectivity at 10.6 p.m. 1.06 p,m, etc. are very highly absorbing in the visible portion of the spectrum. This enhanced absorption in the visible portion of the spectrum provides for very low damage thresholds when subjected to visible continuous wave and repetitive pulsed lasers. Thereare, of course, visible optical systems which are very sensitive to the visible portion of the spectrum, i.e., the eyes of a human being. Equations are provided for one and three dimensional analysis of temperature gradients in the optical thin films and slip and melt thresholds for metallic substrates. Further, equations are provided for both the semi-infinite plate boundary condition and for those substrates that have a thickness less than required for semi-infinite plate boundary using the Reverse Thermal Wavemodel. Pictures of in band and out of band damage are provided and curves are plotted for the various coatings on commonly used substrate materials.