The roof/umbrella/whatever color reflects the energy since a laser is a single frequency. AFAIK, there are no laser diodes that can change their resonant frequency (except maybe a small tuning) , so they are stuck with a particular frequency once built and deployed. Large laser weapons are made up of many smaller laser diodes that have their beams combined, so this would complicate changing frequency even if possible.
Here's the problem. Suppose that a target surface was 90% reflective at whatever wavelength you care. 10% would still get through and heat up the material. If you are working only at the level of tens of watts, then, yes, the "reflective" panel will survive because the leakage is within its thermal tolerance. Get high enough for weapon effects and the leakage is high enough to degrade the reflectivity and the whole process destroys the target. We studied targets that were mirror-polished metal. At open-fire intensities of a hundred watts/cm2, the leakage was enough to destroy the reflectivity. We dreamed up the possibility of a "cleanly-degrading polymer" coating, and it worked out the same way. The CDP would just evaporate and expose the bare metal again. This was 50 years ago.
But if visible light lasers had been at work, people would have seen the light flashes. No such reports.
If it was an infrared beam (which it would have to be, since that is the focus of all research in that area since the 1970s), neither you nor a camera would "see" any light from a scattered beam.
And if it were a weapon-class laser, the odds would be high that anyone who saw it directly or semi-directly would be blinded by the radiation. Zap yourself in the eye with a laser pointer and find out what 5 milliwatts looks like. Nothing to repeat.
The roof/umbrella/whatever color reflects the energy since a laser is a single frequency. AFAIK, there are no laser diodes that can change their resonant frequency (except maybe a small tuning) , so they are stuck with a particular frequency once built and deployed. Large laser weapons are made up of many smaller laser diodes that have their beams combined, so this would complicate changing frequency even if possible.
Here's the problem. Suppose that a target surface was 90% reflective at whatever wavelength you care. 10% would still get through and heat up the material. If you are working only at the level of tens of watts, then, yes, the "reflective" panel will survive because the leakage is within its thermal tolerance. Get high enough for weapon effects and the leakage is high enough to degrade the reflectivity and the whole process destroys the target. We studied targets that were mirror-polished metal. At open-fire intensities of a hundred watts/cm2, the leakage was enough to destroy the reflectivity. We dreamed up the possibility of a "cleanly-degrading polymer" coating, and it worked out the same way. The CDP would just evaporate and expose the bare metal again. This was 50 years ago.
But if visible light lasers had been at work, people would have seen the light flashes. No such reports.
If it was an infrared beam (which it would have to be, since that is the focus of all research in that area since the 1970s), neither you nor a camera would "see" any light from a scattered beam.
And if it were a weapon-class laser, the odds would be high that anyone who saw it directly or semi-directly would be blinded by the radiation. Zap yourself in the eye with a laser pointer and find out what 5 milliwatts looks like. Nothing to repeat.