Pressure gauge with fiber optic sensor

A pressure responsive controller providing an output that varies substantially linearly with linear changes in pressure, the controller optically coupled to a non-linear pressure responsive device, the pressure responsive device randomly selected from available pressure responsive devices, comprising:

• a first light source/light detector pair,
• a second light source/light detector pair,
• a reflective target mounted to the randomly selected non-linear pressure responsive device for non-linear movement in response to linear changes in pressure applied to the pressure responsive device,
• a reference target mounted in a fixed position in relation to the reflective target,
• a first fiber optic cable for transmitting light from the first light source to the reflective target,
• a second fiber optic cable for transmitting light reflected from the reflective target to the light detector of the first detector pair, the intensity of the reflected light varying in a manner corresponding with the non-linear movement of the reflective target,
• a third fiber optic cable for transmitting light from the light source of the second detector pair to the reference target,
• a fourth fiber optic cable for transmitting light reflected from the reference target to the light detector of the second detector pair,
• a first control circuit connected to the light detector of the first detector pair and responsive to the output thereof to generate a non-linear indication of the linearly varying pressure applied to the non-linear pressure responsive device,
• a second control circuit connected to the light detector of the second pair and responsive to the output thereof to generate a reference indication,
• circuit means responsive to the non-linear indication from said first control circuit and the reference indication from the second control circuit and generating a detector voltage that varies in a manner corresponding with the movement of the reflective target and varies non-linearly with the linearly varying pressure applied to the non-linear pressure responsive device;
• and
• output means including a look-up table with a single set of controller outputs for receiving the detector voltage and selecting from the single set of controller outputs of the look-up table in accordance with the detector voltage a sequence of controller outputs that varies substantially linearly with linear changes in applied pressure.

A pressure responsive controller providing an output that varies substantially linearly with linear changes in pressure as measured by a randomly selected pressure responsive device that responds with movement in a substantially non-linear manner relative to a reference position in response to a linear pressure change, comprising:

• a light source/light detector pair,
• a reflective target mounted to the pressure responsive device and movable therewith,
• a first fiber optic cable for transmitting light from the light source to said reflective target,
• a second fiber optic cable for transmitting light reflected from the reflective target to the light detector of said pair,
• a control circuit connected to the light detector of said pair and responsive to the output thereof to generate a detector voltage that varies non-linearly with the non-linear movement of the reflective target, and
• means including a look-up table with a single set of controller outputs for any randomly selected pressure responsive element for receiving the non-linear detector voltage and selecting from the controller outputs of the look-up table in accordance with the detector voltage a sequence of controller outputs that varies substantially linearly with linear changes in pressure applied to said flow through pressure responsive device.