You know Evanescent light has no diffraction limit and it having a lot of information related to nano-particle to the atomic level but it is lost and not participate as far-field. I have heard that by using SIL (Solid Immersion Lens) we can convert this evanescent field to the far field to improve the spatial Resolution. In such case the sample is positioned on a hemispherical lens, which collects the light. Due to refraction at the surface of the lens, all travelling light ends up in a cone around the normal, and this cone has an opening angle equal to the critical angle of total internal reflection of the lens-air interface. Evanescent waves, radiated by the sample, can be converted into travelling waves at the interface provided their wavelength is not too short, and they are transmitted under an angle larger than the critical angle. In this way, part of the evanescent waves can be measured in the far field, improving the resolution of the image. Why we use hemispherical shape?? can anyone explain this in easy words?
Thanks @ Takashi Hira. I want to say that can we simulate that kind of things like SIL or hyperlens???? if yes then which software suites us???
You can think of the problem as a two steps process:
1. imagine a dense and less dense boundary support an evanescent field, by putting a block of glass in contact with the boundary, some of the evanescent field will be converted into propagating wave.
2. if the glass block in 1) above is a SIL, the wave can be coupled to free space and be available for imaging purpose. In this case, the Imaging NA will be increased by a factor of n, n being the refractive index of the SIL. If you use what is called an aplanatic SIL, you will find that the improvement can reach n^2.
Have a look at APL., 85, 5451-5453 (2004). I think it contains discussion of the two types of SIL.
Best.
Ok if i want to study this then which simulator i have to used which support like this simulations??? One of this simulation is as attached
Thank you very much for your reply... Dear Hira i am doing PhD so i am not Dr. Yet. I have noted that Evanescent light has no diffraction limit and SIL can take the Evanescent Light from the Particle because Evanescent is along the radius of the particle. Evanescent Light attenuated along Z- direction but not along X or Y direction. But My question is that how can we study it in a simulation??? Which simulator we should Use????????
Oh wao Great reply... Miss Hira i am really grateful to you you cant imagine that how your that reply increase my knowledge. because this field is new for me. My MS field Was Semi-conductor Physics. I can study semi-conductor devices well so now this is challenging for me.. I am using Opti-FDTD you may know it. I am using 100 nm Silicon sphere to study the Evanescent Field Scattering. You have told me about DDA its a code or a simulator??? sorry i have not strong programming background i have used Sentaurus TCAD for 1 year. Today i have done my simulation by using Opti-FDTD by the company Opti-Wave. Here i used the 550 nm wavelength. Two observation areas one is for analsing reflected power and other is for transmission power. Here I have used Lorentz Druse Model. Now my question is that how i can get the result as in the paper as i have sent to you. Kindly guide to me I shall be very grateful to you for this....
Sorry,Hira is the name of female so thats why i thought you are a female. PhD researcher means you are doing research in PhD. It does not mean that you have already got PhD i think you have confusion with that or may be it vary with respect to country to country.
Opti-FDTD and Lumeric FDTD are different. Have you any example related to Evanescent field scattering through a nanao-particle????
It is indeed possible to use any high refractive index material in any shape. But the hemishpherical shape is due to the fact the ray which falls on the them crosses the surface perpendicular and hence the optical aberration picked up is minimum in forward and backward direction of propagation.
which material is like these??? and what are the newest way to get this evanescent light out???? can we change the light direction and make the direction of evanescent light wave scattering in this way that it comes out???? make a specific angle of the light???
In general these materials are high index glass, as the transmission of the light (high transmission through the material) is important. Actually the light from SIL interacts with the sample in the near field and then the reflected light from sample is collected back. The collection of light in reflection is done by the same illumination optics (epi- illumination configuration). Hence in reflection you get back the light at angles identical to your illumination.
Can we perform such kind of simulation? i mean SIL simulation and investigating evanescent light????
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