top view thereof although the function of the sensor device 200 is described herein with reference to the system 100 it is understood that the invention is not so limited but that the sensor device 200 may function with any type of processing system as mentioned briefly above the processing system 100 includes a central transfer chamber 112 as the center of activity in the handling of wafers or substrates through the system 100 the transfer chamber 112 typically mounts on a platform 121 the transfer chamber 112 has process chambers 114 attached at facets 113 the process chambers 114 may be any type of process chamber such as a physical vapor deposition chamber a chemical vapor deposition chamber an etch chamber etc it is not uncommon for a manufacturer of process chambers to provide over twenty different types of process chambers the process chambers 114 may be supported by the transfer chamber 112 by the platform 121 or on their own platforms depending on the configuration of the individual process chambers 114 slit valves not shown in the facets 113 provide access and isolation between the transfer chamber 112 and the process chambers 114 correspondingly the process chambers 114 have openings not shown on their surfaces.