The Most Reflective Mirror In The World

this is the world's most reflective type of mirror called a dielectric mirror it reflects over 99.5 percent of visible light so to give you an idea how reflective this is I was actually looking for the reflector that I had set down on my table here and I couldn't find it and I was like oh what's this white paper here and this is actually the reflector reflecting off of the white wall it's literally the same brightness as the white wall here like that is just crazy normally when you hold a mirror up you can easily see it's a mirror because it's a slightly grayer it's grayer because it's absorbing some light but look at this it like disappears into the wall it's only when I turn it away and shine it at the darker floor that you can actually see it but when it's reflecting off the wall it just disappears but not only that it has no Brewster angle which means that no matter what the angle of light is that hits it it'll still be reflective which means you can do some pretty neat stuff with it if I roll it in a tube and pinch off one end of it then it suddenly looks like I'm holding a flashlight in my hand that turns on and off when I pinch it because all the light from the room that would have exited the other end of the tube now bounces around and then exits the front of the tube so virtually no light gets wasted any light that goes into the tube comes right back out 99.5 reflectance is amazing for comparison this mirror or any other regular residential mirror only reflects about 60 percent of the light that hits it a good way to compare the reflectiveness of this is to put it on a regular mirror and then reflect the white wall behind me so you can see how much lighter and brighter this reflectance is than the mirror behind it higher grade Optical mirrors like this one can get as high as 90 or 95 percent reflectance but still nothing compared to this dielectric mirror I got this material from 3M when I visited their Innovation Center it's called a 3M enhanced specular reflector or ESR film after 3M developed this mirrored film they weren't fully aware of its Optical properties but one day an engineer was in a long meeting and was holding some of this film in his hand he was just playing around rolling it up and noticed the same thing that we just saw here when he rolled it up and pinched one end it became very bright now this confused him because he knew that this was made of dielectric material which meant that it should have what's called a Brewster angle the Brewster angle is the angle at which the reflection off the surface becomes completely polarized but if that were happening the light should extinguish really quickly and not bounce around and come back out the tube you can imagine how many times it's bouncing off the surface here before it leaves after some research they found that the equations that derived The Brew string angle where for isotropic materials only meaning materials that look the same no matter what direction you looked at them but this material was made of a polymer that looked like spaghetti stretched out on the microscopic scale so it looked different depending on which angle or which direction you were looking at it so what they did is they derived the equation for anisotropic materials and sure enough they discovered that it doesn't have a booster Angle now the results of this are a big deal this meant that it's an extremely efficient reflector especially for polarized light that's usually found in cell phones in fact this material right here is probably one of the reasons that you're watching this video on a cell phone today when cell phones were being developed one of the biggest setbacks for cell phones is that they had horrible battery life the display actually used most the battery due to the need for multiple lights but then this material was introduced as a way to light up the entire display with only one light you can see how it efficiently spreads the light over the whole surface so this material began to be used everywhere in cell phone displays and countless other electronic displays and made cell phones last much longer become much more practical for everyday use and before we continue I'd like to thank the sponsor for this video better help these last few years have been difficult for everyone and one of the most important things you can do in times like this is to focus on your mental health betterhelp is the world's largest therapy service and it's a hundred percent online with better help you can tap into a network of over 30 000 licensed and experienced therapists who can help you with a wide range of issues to get started you just answer a few questions about your needs and preferences in therapy that way better help can match you with the right therapist from their Network then you can talk to your therapist however you feel comfortable whether it's via text chat phone or video call and you can message your therapist anytime and schedule a live session when 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here you can see the step down of each layer and you can see that they're all transparent but when you get them all on top of each other it makes it so it's a reflective surface so how does transparent plastic make something so reflective well let's look at what happens when light hits something that's transparent right at the surface between the air and the material some of the light gets reflected and some of the light gets transmitted meaning it goes into the material the light that goes into the material bends a little bit depending on the refractive index now if we put another transparent material right below this layer with a different refractive index then the light will do the same thing some will get reflected and some will get transmitted in this case the two path lengths of the beam differ by exactly one wavelength which means you get constructive interference so you're gaining back the light that went into the material by continually reflecting it off the bottom layers to do this you have to layer it in very thin layers that alternate from high to low refractive index if you do it just right then you can get almost perfect reflectance and what's neat is that the thickness of these layers can be tuned to whatever wavelength of light you want to be reflected or transmitted so you can get some really cool colors with different layers of these polymers as opposed to just complete reflectance so the most reflective mirror in the world actually is made up of a bunch of parts that aren't reflective at all this is definitely an example where the sum of all the individual Parts have different properties than the entire thing as a whole and thanks for watching another episode of the action lab I hope you enjoyed it if you did don't forget to subscribe to my channel if you haven't yet and if you have any comments or questions let me know in the comments section I'll try to get to them and thanks for watching and we'll see you next time foreign

Channel: The Action Lab

Views: 1,006,894

Keywords: the action lab, most reflective mirror in the world, mirror room, ESR, 3M, 3M ESR, dielectric mirror

Id: JM_lXKmWYDI

Length: 7min 34sec (454 seconds)

Published: Fri Aug 11 2023