Zeta wrote:Is first surface mirror and one way mirror the same?
No. A common mirror (such as the one from a bathroom) is a piece of glass that has silver coating on its back side. If you are looking to the mirror and scratch the surface, you actually scratch a glass, not the silver layer. If you put a finger close to the mirror, you see its strong reflection from the silver back side and a weak reflection from the front glass surface.
A first surface mirror is coated on the front surface. It can be easily damaged, it is better not to touch it at all. But for optics, it is much better than a common mirror. Here is the reason.
If you illuminate a front surface mirror with a laser, you get a perfect reflection.
If you illuminate a common mirror with a laser, you get two reflections, one from the back silver surface and one (weak) wrom the first one. These reflections interfere and create a banded structure. These bands are very disturbing in dispay holography.
I got a nice (and large) front surface mirror from suppliers for DYI projectors. You can also fined ones in old overhead projectors, scanners and maybe other electro-optical devices. You can also use platters from an old hard disk. In short: anything perfectly flat with one reflecting surface.
A one way mirror is something completely different. It is a piece of glass coated with a thin layer that is partially transparent and partially reflects light, e.g. in ratio 50:50. If you look at such glass and there is darkness behind it, you see a perfect mirror reflection. If, on the other hand, the environment behind the glass is much brighter than the environment in front of it, you can see throuh. It is just a matter of fact if transmitted light is stronger or weaker than reflected light. A common architectural application is a one-way mirror between a well illuminated stage and a dim control room. Those inside the control room can see the stage, but not vice versa.
In fact, a one way mirror is called a beam splitter by opticians. However, common one way mirrors can be far from quality required by precision beam splitters.
Hope this helps.