Mechanical Input Transducers 



1-1. Transducers for Linear Dimensions 

 (Length or Thickness Gauges) 



The following transducer systems furnish an electric signal which 

 can serve as a measure of a linear distance between two limits, of a 

 thickness or of a length. The systems are based on either a resistance 

 variation (1-1 la), 1 a variation of current flow pattern (1-116), an 

 inductance variation (1-12), or a capacitance variation (1-13). A 

 method based upon the electric breakdown voltage is described in 

 1-14. Thickness of test objects can also be measured with sonic 

 methods (1-15) and from the absorption of radiation (alpha-, beta-, 

 gamma-, and X-ray gauges, 1-16). 



Distance and thickness measurements can also be made with 

 the help of displacement transducers (described in 1-2). Further 

 methods, primarily applicable to liquids, are described in 1-4. 



For a summarizing review, see George Keinath, The Measurement of Thick- 

 ness, Natl. Bur. Standards Circ. 585, Jan. 20, 1958. 



1-11. Resistive Systems 



a. Contact on Both Sides. The length of a wire or the thickness / of 

 a prismatic body with the resistivity p clamped between two elec- 



1 Cross references in this book are multiple -numbered. "1-1" refers to chapter 

 1, part 1 ; "la" designates the section of the part and its lettered subdivision. 



7 



