Cold and Warm Light Mirrors

Without protection, the lamp in a projector would heat those precious slide and video images to melting. How to Save Our Slides? This exhibit shows the effect of different coatings on glass plates. One coating allows the glass to transmit heat (long-wave infra-red radiation), but reflects most of the light (shorter-wave radiation). The other transmits light, but reflects heat – this is what the projector needs. See and feel the difference.