System for locating breaks in fiber optic filaments

• US 3,981,592 A
• Filed: 03/31/1975
• Issued: 09/21/1976
• Est. Priority Date: 03/31/1975
• Status: Expired due to Term

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Williams, Donald N.
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US05/563,751
• Time in Patent Office: 540 Days
• Field of Search: 356/4, 356/5, 356/237, 356/239, 250/227, 250/562, 250/572, 250/339, 250/199, 350/96 C
• US Class Current: 356/73.1
• CPC Class Codes: G01B 11/02 for measuring length, width or thickness G01B11/08 takes precedence
• CPC Class Codes: G01M 11/3109 Reflectometers detecting the back-scattered light in the time-domain, e.g. OTDR

Abstract

A system for locating breaks in fiber optic filaments employs light energyulses which are controlled to be emitted at determinable times and directed along the light path of the fiber optic filaments under test. A pulse detector is positioned to receive any reflected pulse light energy from the fiber optic filaments and an indicator is responsive for indicating the elapsed time between the emission of the pulses and the reception of the reflected pulse light energy, preferably calibrated in terms of distance to establish the location of breaks in the fiber optics line.

Claims

1. A system for locating breaks in fiber optic filaments transmitting light energy signal information from a first source comprising:

a second source of light energy pulses having a frequency distinguishably different from said light energy signal information;

means for directing said pulses along the light paths defined by the disposition of said fiber optic filaments;

a control circuit for controlling the emission of said pulses from said second source at a determinable time;

a pulse detector positioned to receive reflected pulse light energy from said fiber optic filaments; and

an indicator responsive to said control circuit and said pulse detector for indicating the elapsed time between the emission of said pulses and the reception of said reflected pulse light energy, whereby to establish the total distance along said light path to the location of breaks in said fiber optic filaments including curvilinear distances due to said disposition of said fiber optic filaments.

2. A system for locating breaks in fiber optic filaments as claimed in claim 1 wherein the wavelengths of said pulses and said light energy signal information are both within the infrared spectrum.

3. A system for locating breaks in fiber optic filaments as claimed in claim 1 wherein said control circuit is responsive to said first source of light energy signal information for interlacing the emission of said pulses between transmissions of said light energy signal information.

4. A system for locating breaks in fiber optic filaments as claimed in claim 1 wherein said indicator is calibrated to indicate said elapsed time in terms of distance along the light path of said fiber optic filaments.

5. A system for locating breaks in fiber optic filaments as claimed in claim 1 wherein the time interval between the emission of successive pulses is not less than the time required for said light energy to traverse the entire length of said light path and return to its point of origin.

6. A system for locating breaks in fiber optic filaments as claimed in claim 1 wherein said control circuit is operative to gate said pulse detector for predetermined time periods in synchronism with the emission of pulses from said source of light energy pulses.