Rick --
There are a couple of US-based rotary table makers that can match the quality of the brands you name -- Moore, M&M Precision, International Machine Tool, A G Davis / AA Gage, and Roto-Technology come to mind -- and Germany's Eimeldingen does build some of their tables in Indianapolis, but you're going to be looking for a long time if you want a more precise table than those imports you name.
Ok, I'm pulling your leg a bit here . . . but the U S builders I mentioned all built very high quality rotary tables that might suit you perfectly.
Also, I'm pretty sure that the Imperial-brand tables were built in Germany by Eimeldingen and imported into the U S by International Machine Tool. After these company disolved their marketing arrangement, IMT began to manufacture their own tables and Eimeldingen began to do their own U S marketing.
John