Showing papers on "Fiber optic sensor published in 1973"

Fiber optic scanners

Abstract: A rod bundle of fiber optic elements transmitting a laser beam are secured at a first location on the rod bundle and driven at a second location on the rod bundle to form a linear scan of the beam. The beam is then collimated and applied to a narrow rectangular bundle of fiber optic elements that are driven orthogonally to the linear scan of the beam to form a scan over a plane surface. The narrow rectangular bundle of fiber optic elements are driven at a lower frequency than the rod bundle of fiber optic elements. All fiber optic elements are driven by electromagnetic or piezoelectric components.

Dynamic measurement of optical fiber diameter

Abstract: This paper describes a novel technique for monitoring the outside dimensions of clad or unclad optical fibers. An oscillating mirror is used to deflect a laser beam with constant velocity across a fiber in order to measure the time interval during which the fiber intercepts the beam and casts a shadow on a photodetector. For 110 μ fibers, individual measurements made every 1/60 sec are repeatable within a spread of ± 1% from the 330 μsec mean time interval (rms deviation ≈ ± 0.6%). Results are displayed in digital form, but can be converted to an analog signal for use in a servo loop to control the pulling rate of fiber drawing machines. An additional feature of the technique is that fibers with noncircular cross sections can be monitored by making sequential diameter measurements along orthogonal axes of the fiber.

Military Applications of Fiber Optics and Integrated Optics

Abstract: A general discussion of military applications of integrated optics and fiber optics is presented. Specific applications discussed are: 1) a multiterminal multiplexed data highway for aircraft and shipboard use; 2) optical fibers as tethers; 3) a 10.6-/spl mu/m heterodyne detector; and 4) integrated optical phased arrays.

Dispersion and equalization in fiber optic communication systems

Abstract: The additional optical power required at the repeater input in a fiber optic communication system due to intersymbol interference is experimentally measured. In the experiment, the intersymbol interference which results from differential mode delay in multimode fibers is minimized with a five-tap transversal equalizer. Error rate measurements are performed using five fibers ranging from 0.01 km to 1.25 km in length. In this manner, the additional optical power required to achieve a given error rate is found as a function of pulse width. The measured values compare favorably with the power penalties predicted by Personick. The trade-off between excess optical power and equalization penalty in dispersion-limited fiber systems is discussed.

Taper Measurement Techniques

Abstract: A sudden increase in the availability of low cost fiber optic tapers has given rise not only to many new and interesting applications, but also to a myriad of measurement and specification difficulties. As with all fiber optic components, the method of specifying and measuring the optical parameters has not been easy. These difficulties, however, are compounded in the case of fiber optic tapers. This paper will endeavor to explain why a variation in fiber diameter along the length of the taper greatly complicates the measurement gathering process for distortion, transmittance and resolution. In addition, measurement techniques based on the fiber diameter variation will be explained.

Vibrating fiber electrometer

Abstract: Improved operation of a vibrating fiber electrometer having a flexible conductive fiber positioned between two deflecting electrodes is achieved by maintaining the pressure of the atmosphere surrounding the fiber at a value where the ratio of the amplitude of vibration of the fiber at its resonance frequency to the amplitude of vibration at twice the resonance frequency is equal to or greater than 5 and having an alternating voltage of frequency equal to the natural frequency of the fiber applied to the deflecting electrodes. Automatic, continuous operation of the vibrating fiber electrometer is attained by projecting the image of the fiber onto a photosensitive detector which develops a signal corresponding to the phase of vibration of the fiber. A servo system coupled to the fiber and the deflecting electrodes and the detector is responsive to the signal to minimize automatically the vibration of the fiber.