Tjhe Fresnel equations tell you how much light will be reflected from the surface of a lens. The amount of light reflected depends on the index of refraction of the glass, and on the angle of the incoming light. The higher the index and the shallower the angle, the more that will reflect.

https://en.wikipedia.org/wiki/Fresnel_equations

For glass, a reflectance of about 4% or 5% is typical. I don't know where the 10% number in your diagram comes from, except that there is also light that reflects when exiting the lens.

There is nothing inherent in a Fresnel lens that changes this 4% reflectance. But, a Fresnel lens will often allow for curvature that a normal lens would never have. This will increase the amount of light that comes in at a shallow angle to the surface, so it will increase the surface reflectance.

On the other hand, Fresnel lenses are often made of plastic. Most plastics (with the exception of "high index" plastics that are used in glasses) have a somewhat lower index than glass. This means that there is less reflection.

It is possible to add an anti-reflective coating to reduce this reflection. MgF is one such coating that has a lower index. Another way to reduce reflection is to add an interference filter to the surface. If you are looking at solar cells (as implied by your drawing) then neither of these are practical. They are expensive for large areas, and prone to scratching.

Another thing to consider is to put "goop" on the underside of the Fresnel lens, so that you do not have an air gap between the bottom of the lens and the top of the "plate". This will significantly reduce the lower surface reflectance.

see following links

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwjXmZjcv8TLAhUWBo4KHUJWAIQQFggpMAI&url=http%3A%2F%2Fwww.bbc.co.uk%2Fschools%2Fgcsebitesize%2Fscience%2Ftriple_ocr_21c%2Ffurther_physics%2Flight_telescopes_images%2Frevision%2F3%2F&usg=AFQjCNHlvTy0EdMIVHSMdQRptVnPIz7b8Q&bvm=bv.116954456,d.c2E

https://en.wikipedia.org/wiki/Lens_flare

https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0ahUKEwjXmZjcv8TLAhUWBo4KHUJWAIQQFgg_MAU&url=http%3A%2F%2Fwww.crizalusa.com%2Ffaq.html&usg=AFQjCNEq6WHvYJH0Dqp5pWhhnUNG8TFzIA&bvm=bv.116954456,d.c2E

Thanks you sir for your help. Here i attach a sample of reflection from glass. Glass will reflect around 10% of radiation. But, is it happen to lens especially fresnel lens?

Answer to your problem is here, http://farside.ph.utexas.edu/teaching/em/lectures/node104.html

Tjhe Fresnel equations tell you how much light will be reflected from the surface of a lens. The amount of light reflected depends on the index of refraction of the glass, and on the angle of the incoming light. The higher the index and the shallower the angle, the more that will reflect.

https://en.wikipedia.org/wiki/Fresnel_equations

For glass, a reflectance of about 4% or 5% is typical. I don't know where the 10% number in your diagram comes from, except that there is also light that reflects when exiting the lens.

There is nothing inherent in a Fresnel lens that changes this 4% reflectance. But, a Fresnel lens will often allow for curvature that a normal lens would never have. This will increase the amount of light that comes in at a shallow angle to the surface, so it will increase the surface reflectance.

On the other hand, Fresnel lenses are often made of plastic. Most plastics (with the exception of "high index" plastics that are used in glasses) have a somewhat lower index than glass. This means that there is less reflection.

It is possible to add an anti-reflective coating to reduce this reflection. MgF is one such coating that has a lower index. Another way to reduce reflection is to add an interference filter to the surface. If you are looking at solar cells (as implied by your drawing) then neither of these are practical. They are expensive for large areas, and prone to scratching.

Another thing to consider is to put "goop" on the underside of the Fresnel lens, so that you do not have an air gap between the bottom of the lens and the top of the "plate". This will significantly reduce the lower surface reflectance.

Thanks a lot prof..