An optical element comprising: a substrate having a first surface and a second surface disposed opposite the first surface; a first multi-layer dielectric film disposed on the first surface of the substrate and constructed and arranged to transmit light in a first band of wavelengths; a second multi-layer dielectric film disposed on the second surface of the substrate and constructed and arranged to transmit light in a second band of wavelengths, the first and the second bands of wavelengths at least partially overlapping; a bilayer diamond-like carbon coating (110, 110a) disposed on the first multi-layer dielectric film, the bilayer DLC coating (110, 110a) including a first layer and a second layer, the first layer having a modulus of elasticity of a first value, and the second layer disposed on the first layer and having a modulus of elasticity of a second value that is greater than the first value; and an adhesion layer disposed between the first multi-layer dielectric film and the bilayer DLC coating; wherein at least one of the first multi-layer dielectric film and the second multi-layer dielectric film comprises one or more stacks of: a high index dielectric layer; a first medium index dielectric layer disposed over and contacting the high index layer; a low index dielectric layer disposed over and contacting the first medium index layer; and a second medium dielectric index layer disposed over and contacting the low index layer, wherein the high index dielectric layer has an index of refraction that is greater than the first medium index dielectric layer, the second medium dielectric layer, and the low index dielectric layer, and the indices of refraction of the first and second medium index dielectric layers (124a, 124b) are greater than the index of refraction of the low index dielectric layer; wherein the high index material is positioned either on or closest to the substrate; and wherein the first and the second bands of wavelengths are configured to transmit visible light having wavelengths of from 0.4 to 0.75 microns and at least one of near-infrared light having wavelengths of from 0.75 to 1.4 microns, short-wavelength infrared (SWIR) light having wavelengths of approximately 1.4-3 microns, mid-wavelength infrared (MWIR) light having wavelengths of approximately 3-8 microns, long-wavelength infrared (LWIR) light having wavelengths of approximately 8-15 microns, and far-infrared light having wavelengths of approximately 15-1000 microns. a substrate having a first surface and a second surface disposed opposite the first surface; a first multi-layer dielectric film disposed on the first surface of the substrate and constructed and arranged to transmit light in a first band of wavelengths; a second multi-layer dielectric film disposed on the second surface of the substrate and constructed and arranged to transmit light in a second band of wavelengths, the first and the second bands of wavelengths at least partially overlapping; a bilayer diamond-like carbon coating (110, 110a) disposed on the first multi-layer dielectric film, the bilayer DLC coating (110, 110a) including a first layer and a second layer, the first layer having a modulus of elasticity of a first value, and the second layer disposed on the first layer and having a modulus of elasticity of a second value that is greater than the first value; and a high index dielectric layer; a first medium index dielectric layer disposed over and contacting the high index layer; a low index dielectric layer disposed over and contacting the first medium index layer; and a second medium dielectric index layer disposed over and contacting the low index layer, wherein the high index dielectric layer has an index of refraction that is greater than the first medium index dielectric layer, the second medium dielectric layer, and the low index dielectric layer, and the indices of refraction of the first and second medium index dielectric layers (124a, 124b) are greater than the index of refraction of the low index dielectric layer; wherein the high index material is positioned either on or closest to the substrate; and wherein the first and the second bands of wavelengths are configured to transmit visible light having wavelengths of from 0.4 to 0.75 microns and at least one of near-infrared light having wavelengths of from 0.75 to 1.4 microns, short-wavelength infrared (SWIR) light having wavelengths of approximately 1.4-3 microns, mid-wavelength infrared (MWIR) light having wavelengths of approximately 3-8 microns, long-wavelength infrared (LWIR) light having wavelengths of approximately 8-15 microns, and far-infrared light having wavelengths of approximately 15-1000 microns.