You can use polarized light microscopy. 

There are also many other linear and non-linear techniques one can use.

Yes we can make detailed study in crystal structure 

You need an imaging technique that resolves the nanofibres (eg SEM) and then Fourier Transform analysis (eg. via ImageJ). Polarised optical microscopy is a good start, but some polymers depolarise the light/laser

https://www.nature.com/articles/srep14580