@Prof-Hafner can you also explain how does it happen that more light is coming through the glass with anti-reflection coating? The phenomenon of destructive reflection of the incoming light is quite clear but how in the same time Light Transmission increases in this type of structures? Thanks.
Can someone please help me? Why does anti reflection coating of lenses have to be a quarter of the wavelength of light, if both of the reflected waves (from the first surface and the second surface) will undergo 180 degree phase change? Won't they interfere constructively in any way, despite the thickness of the coating, since the reflected rays will be exactly the same as the incident wave, except they BOTH will be 'flipped upside down', having the same phase (no phase change between the two reflected waves)? Both of the reflected waves should undergo 180 degree phase change and therefore, interfere constructively.
In addition to the phase shifts on reflection, *one travels farther than the other*. That is what gets them out of phase. Here is a lecture on it: ruclips.net/video/efCzm574OWQ/видео.html
@@Prof-Hafner Thank you very much for responding. I already know that information. I can’t actually visualise how thickness of the AR coating would affect the interference between the reflected waves (whether it would be constructive or destructive). If the reflected wave doesn’t undergo 180 degree phase change, it would just travel back along the same path. If it does undergo 180 degree phase change, it would travel back along the same path, but just flipped upside-down. In other words, despite the thickness of the AR coating, shouldn’t the phase of the reflected waves always be the same? If both of the reflected waves undergo 180 degree change, shouldn’t they always be the same at any moment in space and time? It’s quite difficult to explain what I mean without diagrams. Is the any chance I can get your email address to send you the diagrams?
The 180 degree phase shift only occurs from lower index of refraction material (air) to higher index of refraction material (coating). If you have n_airn_glass, we do not get the additional 180 degree phase shift, so only a 360 degree phase shift - thus, the original light (phase shift 180 degrees) and the transmitted-reflected light (phase shift 360 degrees) destructively interfere since their phase difference is 180 degrees. You can try and think bout what a reflecting coating would work like. In this case we want the original light reflected off of the air-coating interface to constructively interfere with the transmitted and then reflected coating-glass light. So here's the same example as the first: n_air
Great video! Thank you!
@Prof-Hafner can you also explain how does it happen that more light is coming through the glass with anti-reflection coating?
The phenomenon of destructive reflection of the incoming light is quite clear but how in the same time Light Transmission increases in this type of structures? Thanks.
Can someone please help me? Why does anti reflection coating of lenses have to be a quarter of the wavelength of light, if both of the reflected waves (from the first surface and the second surface) will undergo 180 degree phase change? Won't they interfere constructively in any way, despite the thickness of the coating, since the reflected rays will be exactly the same as the incident wave, except they BOTH will be 'flipped upside down', having the same phase (no phase change between the two reflected waves)? Both of the reflected waves should undergo 180 degree phase change and therefore, interfere constructively.
In addition to the phase shifts on reflection, *one travels farther than the other*. That is what gets them out of phase. Here is a lecture on it:
ruclips.net/video/efCzm574OWQ/видео.html
@@Prof-Hafner Thank you very much for responding. I already know that information. I can’t actually visualise how thickness of the AR coating would affect the interference between the reflected waves (whether it would be constructive or destructive). If the reflected wave doesn’t undergo 180 degree phase change, it would just travel back along the same path. If it does undergo 180 degree phase change, it would travel back along the same path, but just flipped upside-down. In other words, despite the thickness of the AR coating, shouldn’t the phase of the reflected waves always be the same? If both of the reflected waves undergo 180 degree change, shouldn’t they always be the same at any moment in space and time? It’s quite difficult to explain what I mean without diagrams. Is the any chance I can get your email address to send you the diagrams?
The 180 degree phase shift only occurs from lower index of refraction material (air) to higher index of refraction material (coating). If you have n_airn_glass, we do not get the additional 180 degree phase shift, so only a 360 degree phase shift
- thus, the original light (phase shift 180 degrees) and the transmitted-reflected light (phase shift 360 degrees) destructively interfere since their phase difference is 180 degrees.
You can try and think bout what a reflecting coating would work like. In this case we want the original light reflected off of the air-coating interface to constructively interfere with the transmitted and then reflected coating-glass light.
So here's the same example as the first: n_air