Fiber optic pressure sensor systems

A fiber optic pressure sensor system comprising:

• an optical fiber having a sensing tip at a first end with a pressure sensitive element, said pressure sensitive element modulating a pressure sensing light signal injected into the opposite second end of said optical fiber and returning said pressure sensing light signal into said fiber,
• temperature sensing means for providing a temperature sensing light signal related to the temperature which said pressure sensing element is exposed to during measurement, said sensing tip including a filter positioned between at said fiber first end and said pressure sensitive element and having a steep transition transmissivity characteristic in a transition wavelength region and means for generating said temperature sensing light signal of a wavelength wherein transmissivity of said filter is affected by temperature and wherein said signal processing means measures the intensity of said temperature sensing light signal thereby providing a measure of said temperature,
• optical means for injecting said pressure sensing light signal into said fiber second end and for receiving said returned light signal, and
• signal processing means for calibrating said light pressure sensing signal modulated by said pressure sensitive element in response to said signal related to temperature thereby enabling accurate measurement of pressure through the range of temperatures.

A fiber optic pressure sensor system comprising:

• an optical fiber having a sensing tip at a first end with a pressure sensitive diaphragm positioned beyond said first end which modulates the energy of a pressure sensing light signal injected into the opposite second end of said fiber which is reflected back into said fiber first end,
• a frequency selective optical filter positioned at said fiber first end which allows transmission of said pressure sensing light signal within a range of operating temperatures and has a steep transmissivity transition characteristics in a transition wavelength region different from that of said pressure sensing light signal, and wherein said wavelength region displaces in wavelength in response to temperature change within said range of operating temperatures,
• a temperature sensing light signal injected into said second fiber end having a wavelength band in the range of displacement of said filter cut-off curve whereby the energy of said temperature sensing light signal reflected by said filter is a function of said temperature,
• optical means for generating and injecting said light signals into said fiber second end and receiving said returned light signals, and
• signal processing means for calibrating said pressure sensing light signal modulated by said pressure sensitive element in response to said signal related to temperature thereby enabling accurate measurement of pressure through the range of temperatures.