What is OLPF Filter in Nikon?
I Heard that D7100 doesn't have this filter for having more details!
Just google for it, there's lots of information about it. Much more than anyone would be willing to type here.
In short, OLPF filters are used for anti-aliasing by artificially causing a tiny little bit of blur. In many cases that is more pleasant to look at, at the expense of a tiny little bit of sharpness.
Generally, what a OLPF filter does can also be achieved by software postprocessing, so certain cameras don't use that filter and leave the decision whether to anti-alias or not to the ambitious photographer who is willing to post-process his shots.
You may know what an OLPF filter is, but you may have to let us in on what it means
All I can think of is the filter you are talking about is maybe the IR cutoff filter, hot mirror or anti-aliasing filter.
There are a few cameras that do not have such a filter.
The Nikon D800e does not have such a filter.