Dear Prabhukrupa Chinmaya Kumar for a good overview on this topic with many additional references please see this book chapter entitled

An Overview of Polymer-Dispersed Liquid Crystals Composite Films and Their Applications

Chapter An Overview of Polymer-Dispersed Liquid Crystal Composite Fi...

The chapter is freely available as public full text on RG.

Prabhukrupa Chinmaya Kumar

There are 2 aspects to this question, as I see it:

• The optimum viewing of different LC structures - basically an optics consideration with polarized light microscopy. The classic book (I just pulled down my signed copy from the bookshelf next to me!) is The Microscopy of Liquid Crystals Norman H Hartshorne Microscope Publications Ltd (1974). This was/is part of the McCrone Group. There's a copy for less than $14 on Abebooks with free shipping in the US: https://www.abebooks.com/servlet/SearchResults?sts=t&cm_sp=SearchF-_-home-_-Results&an=&tn=The+Microscopy+of+Liquid+Crystals&kn=&isbn=
• Generation of the appropriate LC phases - this may involve a heated stage - such as nematic, smectic (e.g. chiral smectic C*) and manipulation of aligned layers (e.g. homeotropic, rubbed polyimide for planar alignment). One reference: Babakhanova G., Lavrentovich O.D. (2019) The Techniques of Surface Alignment of Liquid Crystals. In: Bulavin L., Xu L. (eds) Modern Problems of the Physics of Liquid Systems. PLMMP 2018. Springer Proceedings in Physics, vol 223. Springer, Cham. https://doi.org/10.1007/978-3-030-21755-6_7

Then we have to consider structures such as reverse twist in TN cells without the correct alignment of the 2 plates...

Dear Prabhukrupa Chinmaya Kumar,

Following the above experts' suggestion, my experience to get the best quality of liquid crystal structures using a polarised microscope, is to use a low magnification objective such as x5 first. You may need to adjust the polarised or analyser by fixing one polariser and moving another polariser direction to find good images. Once you have a good image, then change the higher magnified objectives such as X15. The higher the objectives are, the shorter the working distance is. So you need to micro-ajustment to get clear images easily for higher magnified objectives. If you want to explore the dark area, you could adjust the direction of polarisation analyser to see clear images of that area.

In my samples, usually 10x for nematics and 20x for smectics works great. However make yourself a big favour and get long working distance objetives like this one: https://www.ebay.com/itm/Leica-PL-Fluotar-20-L-BD-Microscope-Objective/233790373849.

However it all depends on what you want to see. In some cases you may want to use planar alignment induction, on others homeotropic alignment induction. For planar a crude way is just rub the slides with a nitrile glove. More proper ways are in literature and it's usually spin coating certain polymers like PVA or polyimides. For homeotropic you can use bare glass or wash it with soap. A more proper way is coating it with oleic acid or other polyimides (check Chapter The Techniques of Surface Alignment of Liquid Crystals

Book Alignment Technology and Applications of Liquid Crystal Devices

We use cells from Instec for homegeneos planar alignment and for homeotropic alignment (hopefully 5-15 µm) and for degenerate planar alignment, spin coat with elvamide.

Asuming polarized optical microscopy with orthogonal illumination, the "black" background must be an isotropic or homeotropic phase. If you press the sample and see colors it was homeotropic and if it doesnt change is isotropic, either molten compound or just air (bubble or an empty part the cell/sample). If you use a condeser, the higher the NA, the more grey that the black will look if it's homeotropic, while it should remain the same if isotropic.

You can study the homeotropic part with conoscopy by using converging light with a condenser, a high magnification (20x or more) objective and a bertrand lens or just removing the ocular of the microscope. You can also use a lambda plate to make the isotropic parts look ""red"" (more like magenta) and also see the optical sign.

Olympus have some nice tutorials in their website. You can also look up in the Chapter Handbook of Liquid Crystals, 8 Volume Set, 2nd Edition

Article In Textures of Liquid Crystals

This also should be quite helpful: https://onlinelibrary.wiley.com/doi/book/10.1002/047007437X

For settings to get good liquid crystal textures nature of solvent and adjustment of temperature conditions are very important.