Empty Office Illusion

I seem to get a lot of work done when no one is around.  I think a lot of people feel that way with the socializing and questions and problems to group solve at work.  What I need is an insert in the window to my office that looks just like the inside of my office only empty with the lights turned out.  For the most part I can handle the interruptions and like to keep my door open so people feel welcome to come talk when they need it but the few times I've really needed privacy for focus time I've had to put up a stinky sign that says something like "Please do not disturb even if the building is burning, I'll figure it out eventually."  The funny thing about the sign is a lot of people would look at it and be like "Well that can't possibly be me, I'm sure he wants to talk to me." and in they'd come.  The other problem with the sign was people would see the sign, peek in the window and then do a little pointy finger dance to ask, "Did you forget to take the sign down or should I still not disturb you."  Yes, I could just get blinds but the problem is blinds present an unknown, am I in there or not?  With an empty office illusion everyone would know.