Fiber optic temperature sensor

• US 4,223,226 A
• Filed: 07/26/1978
• Issued: 09/16/1980
• Est. Priority Date: 07/26/1978
• Status: Expired due to Term

• Current Assignee: Rockwell International Corporation
• Original Assignee: Rockwell International Corporation
• Inventors: August, Rudolf R., James, Kenneth A., Quick, William H., Strahan, Virgil H. Jr., Nichols, Donald K.
• Primary Examiner(s): Willis, Davis L.
• Application Number:
  US05/928,223
• Time in Patent Office: 783 Days
• Field of Search: 250/461 R, 250/458, 250/459, 73/355 R, 73/356
• US Class Current: 250/458.1
• CPC Class Codes: G01K 1/024 for remote indication
• CPC Class Codes: G01K 11/3213 using changes in luminescence, e.g. at the distal end of the fibres

Abstract

An inexpensive, lightweight fiber optic micro-sensor that is suitable for applications which may require remote temperature sensing. The disclosed temperature sensor includes a phosphor material that, after receiving incident light stimulation, is adapted to emit phosphorescent radiation output signals, the amplitude decay rate and wavelength of which are functions of the sensed temperature.

Claims

1. A pulse-width-modulated temperature sensor comprising:

a source of light pulses,

a first optical fiber,

one end of said first optical fiber being positioned in proximity to said source of light pulses to receive light pulses therefrom,

a supply of photoluminescent material which has an emission amplitude decay rate which is a function of a temperature to be sensed to which said phosphor is exposed, said phosphor being located in proximity to another end of said first optical fiber to receive light therefrom,

photodetector means,

a second optical fiber,

one end of said second optical fiber being positioned to receive light from said photoluminescent material and another end of said second optical fiber being positioned to deliver light to said photodetector means, thereby to conduct output phosphorescent emission signals thereto,

signal amplitude regulating means connected to an output terminal of said photodetector means to receive therefrom electrical signal representations of the output phosphorescent emission signals and to adjust an initial amplitude thereof to a common signal level, and

pulse width detector means connected to an output terminal of said signal amplitude regulating means, said pulse width detector being connected to measure the width of the amplitude adjusted signal representations of the output emission signals, whereby the width of said adjusted signal representations is indicative of the temperature to be sensed.

2. A temperature sensor comprising:

an optical fiber,

a light source positioned in light supplying relationship to one end of said optical fiber,

a photoluminescent material in light receiving relationship to another end of said optical fiber, said photoluminescent material being of the type having a luminescence when excited by light supplied thereto from said light source, said luminescence providing an indication of a temperature to be sensed,

photodetector means responsive to the luminescence of said photoluminescent material, and

signal amplitude regulating means connected to an output terminal of said photodetector means to receive therefrom electrical signal representations of the luminescence and to initialize the amplitudes of said electrical signal representations to a common signal level.

3. The temperature sensor of claim 2, wherein said signal amplitude regulating means includes:

a variable gain amplifier to receive from said photodetector means the electrical signal representations of the luminescence, and

means to control the gain of said amplifier, whereby the amplitudes of the representations of said luminescence are initialized to the common signal level.

4. The temperature sensor recited in claim 3, further including a pulse width detector connected to an output terminal of said variable gain amplifier for measuring the width of the amplitude initialized electrical signal representations of said luminescence, whereby the width of said electrical signal representations is indicative of the temperature to be sensed.