Abstract: A strain sensor uses optical fibers including strain insensitive portions and a strain sensitive portion. The optical fibers form a sensitive arm of an optical phase locked loop (OPLL). The use of the OPLL allows for multimode optical fiber to be used in a strain insensitive configuration. Only strain information for the strain sensitive portion is monitored rather than the integrated strain measurements commonly made with optical fiber sensors.

Abstract: In an LED a large portion of the light produced is lost due to total internal reflection at the air-semiconductor interface. A reverse taper of the semiconductor is used to change the angle at which light strikes the interface so that a greater portion of the light is transmitted.

Abstract: A strain sensor is constructed from a two mode optical fiber. When the optical fiber is surface mounted in a straight line and the object to which the optical fiber is mounted is subjected to strain within a predetermined range, the light intensity of any point at the output of the optical fiber will have a linear relationship to strain, provided the following equation is less than 0.17 radians ##EQU1## where n.sub.co represents the refractive index of the core, k represents the wavenumber of the light, L represents the length of the optical fiber, S.sub.1 represents axial strain, V is ##EQU2## U is a solution to the eigenvalue equation of the optical fiber, v.sub.f represents the Poisson ratio, P.sub.ef represents the effective strain-optic coefficient of the optical fiber and n.sub.ln represents ##EQU3## where K.sub.

Abstract: An optical fiber comprising a fiber core having a longitudinal symmetry axis is provided. An active cladding surrounds a portion of the fiber core and comprises light-producing sources which emit light in response to chemical or light excitation. The cladding sources are oriented traversely with respect to the longitudinal axis of the fiber core. This polarization results in a superior power efficiency compared to active cladding sources that are randomly polarized or longitudinally polarized parallel with the longitudinal symmetry axis.

Abstract: A strain sensor uses an optical fiber including a strain sensitive portion and at least one strain insensitive portion. The strain sensitive portion is mounted on the surface of a structure at a location where a strain is desired to be measured. The strain insensitive portion(s) may be fused to the strain sensitive portion to transmit light therethrough, so that the resulting pattern may be detected to determine the amount of strain by comparison with a similar fiber not subjected to strain, or with the light pattern produced when the fiber is not under strain.

Abstract: An optical fiber fluorosensor is provided having a portion of a fiber core which is surrounded by an active cladding which is permeable by the analyte to be sensed and containing substances which emit light waves upon excitation. A remaining portion of the fiber core is surrounded by a guide cladding which guides these light waves to a sensor which detects the intensity of waves, which is a function of the analyte concentration. Contrary to conventional weakly guiding principles, the difference between the respective indices of refraction of the fiber core and the cladding is greater than approximately 0.01. In an alternative embodiment, the fiber core is surrounded by an active cladding which is thin enough such that its index of refraction is effectively that of the surrounding atmosphere, whereby the atmosphere guides the injected light throughout the fiber core.

Abstract: An optical fiber is provided comprising an active fiber core which produces waves of light upon excitation. A factor ka is identified and increased until a desired improvement in power efficiency is obtained. The variable "a" is the radius of the active fiber core and "k" is defined as 2.pi..lambda., wherein .lambda. is the wavelength of the light produced by the active fiber core. In one embodiment, the factor ka is increased until the power efficiency stabilizes. In addition to a bare fiber core embodiment, a two-stage fluorescent fiber is provided wherein an active cladding surrounds a portion of the active fiber core having an improved ka factor. The power efficiency of the embodiment is further improved by increasing a difference between the respective indices of refraction of the active cladding and the active fiber core.

Abstract: A radio frequency strain monitor includes a voltage controlled oscillator for generating an oscillating signal that is input into a propagation path. The propagation path is preferably bonded to the surface of a structure to be monitored and produces a propagated signal. A phase difference between the oscillating and propagated signals is detected and maintained at a substantially constant value which is preferably a multiple of 90.degree. by changing the frequency of the oscillating signal. Any change in frequency of the oscillating signal provides an indication of strain in the structure to which the propagation path is bonded.

Abstract: A method for detecting and measuring trace amounts of aerosols when reacted with ozone in a gaseous environment wherein a sample aerosol is exposed to a fixed ozone concentration for a fixed period of time, a fluorescer added to the exposed sample and thereafter the sample heated in a 30.degree. C/minute linear temperature profile to 200.degree. C. undergoes thermoluminescence the trace peak thereof is measured and recorded as a function of the test aerosol and wherein the recorded thermoluminescence trace peak of the fluorescer is specific to the aerosol being tested.

Abstract: A method for detecting and measuring trace amounts of pollutants of the group consisting of ozone, nitrogen dioxide and carbon monoxide in a gaseous environment wherein a sample organic solid material that will undergo a chemical reaction with the test pollutant is exposed to the test environment and thereafter, when heated in the temperature range of 100.degree.-200.degree.C., undergoes chemiluminescence that is measured and recorded as a function of concentration of the test pollutant and wherein the chemiluminescence of the solid organic material is specific to the pollutant being tested.