Is "Microsoft Windows CE 6.0 / Magnet Field" operating system the sole property of TOPCON total station or it can be found in other total stations as well?
Not sure I completely understand your question, but "Microsoft Windows CE 6.0 / Magnet Field" is a combination of the base operating system (Windows CE 6.0) and Topcon's proprietary software "Magnet Field".
Windows CE is quite old and no longer supported by Microsoft. You will find it still used in quite a few GPS devices, however. Trimble's TSC3 still ships with Windows CE.
Magnet Field, I believe, would only be found on Topcon equipment.
One interesting post found on a Microsoft forum indicates Topcon has full control over the software image and any adjustments would be cost-prohibitive.