The apparatus may include a fixture for supporting the sensor and holding {HEAD ~ the sensor} in {TAIL ~ the substantially fixed position} 
in
The apparatus may include a fixture for supporting the sensor and holding { HEAD ~ the sensor } in { TAIL ~ the substantially fixed position }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL