Antireflective coatings work by providing destructive interference at
certain wavelengths.  To calculate the correct thickness, first identify the
wavelength (in air or vacuum) you wish to work with.   To achieve an
antireflective coating, you must "match" wave impedances.  The basic
requirements are:

1)  eta(coat) = sqrt [eta(sub)*eta(air)],
where eta = |E|/|H|(wave impedance), coat = coating, sub = substrate, air =
air (or vacuum, etc.)

2)  coating thickness = N*wavelength(coat) / 4,
where N =any odd integer

Multiple quarter-wave coatings will broaden the range of wavelengths with
good reflection prevention.

TBJ


> Dear friends
>     Can anybody give me the information regarding the
> thickness of SiNx and MgF2 thin layers for
> antireflective applications.
>      I will be very much thankful.
>
> Yours
>
> K.C.Mohite


________________________________________________
Thomas B. Jones
Professor of Electrical Engineering
University of Rochester
Rochester, NY   14627   (USA)
phone:  1-585-275-5233    NEW AREA CODE
fax:    1-585-273-4919    NEW AREA CODE
research website:            www.ece.rochester.edu/users/jones/
electrostatics demos: www.ece.rochester.edu/~jones/demos/
________________________________________________