An optical RF spectrum analyzer which is suitable for determining the reaime spectral frequency content of radar return signals. The optical RF spectrum analyzer includes a demodulator for demodulating an input RF signal to produce a time-varying voltage signal at its output, and a sample and hold circuit for sampling the time-varying voltage signal to obtain and hold a prescribed number of samples of the time-varying voltage signal during each of successive prescribed frame intervals. At the conclusion of each frame interval, the samples obtained and held during that frame interval are applied to respective inputs of a laser array to drive respective ones of the lasers in the array, whereby the laser array produces a spatial pattern of infrared radiation having a spatial intensity distribution which is indicative of the amplitude distribution of the envelope of the input RF signal over a given frame interval. A first optical subsystem directs the spatial pattern of infrared radiation to strike an exposed surface of the electron trapping (ET) material of a spatial light modulator (SLM). A second optical subsystem directs coherent blue light generated by an argon laser to illuminate the exposed surface of the ET material. The incident infrared radiation releases trapped electrons in the ET material at the exposed locations, resulting in the emission of incoherent visible light. The incident coherent blue light is selectively absorbed at these exposed locations as it acts to excite ground state electrons back into energy traps. The incoherent visible light which is emitted by the ET-SLM is filtered out by a blue light filter. The coherent blue light which passes through the ET-SLM is Fourier transformed by a Fourier lens, and then detected by a CCD detector. The spatial light intensity distribution of the coherent blue light detected by the CCD detector, and thus, the electrical output of the CCD detector, are indicative of the spectral intensity distribution of the input RF signal. A video display device responsive to the electrical output of the CCD detector provides a video display indicative of the spectral intensity distribution of the input RF signal.
Disclosed is a novel apparatus and method for volumetric dilatometry. A volumetric dilatometer includes an optical displacement sensor and a means for using a gap measurement obtained from the displacement sensor application in an application which requires the measurement of absolute distance and/or displacement. A novel signal-processing algorithm for volumetric dilatometry is also disclosed. The signal-processing algorithm includes a step for recovering the phase information from a spectral signal by taking the Fourier transform of a spectral signal and deriving a sensor gap measurement from the phase information. A micro-translation stage is provided for automated positioning of the optical sensor and automated re-leveling in an out-of-range condition. A heat source is consists of a vertical tube furnace, such as those found in drywell technologies. Further disclosed is a novel sealed-cell design which consists of a mercury reservoir, a sample cell capable of locking onto the bottom of the mercury reservoir and an outer reservoir sleeve for sensor-to-cell alignment during sensor positioning.
An acousto-radio frequency modulator and an apparatus employing the same are disclosed. The acousto-radio frequency modulator includes a radiowave waveguide including a first end defining an input and a second end defining an output; an acousto-radio material positioned in the signal path of the radiowave waveguide; and a acoustic source coupled to the acousto-radio material and capable of driving an acoustic signal through the acousto-radio material. The apparatus includes a plurality of ARFMs, each capable of modulating a component of a received RADAR signal received by the antenna; a frequency combiner capable of frequency multiplexing each of the components into a combined signal; a filter capable of filtering the combined signal; an amplifier capable of amplifying the filtered signal; and an analog to digital converter capable of converting the amplified signal to a digital representation.
A signal processing apparatus for providing concurrent electrical frequency measurements of multiple, time-coincident signal inputs. In one embodiment of the present invention, an input signal is received that contains a plurality of individual signals independent of each other in frequency, phase, and electrical amplitude. A power splitter splits the input signal into two separate input signals. A delay line introduces a time delay to one of the two separate input signals. Two Bragg cells within a channelized optical phase measurement (COPM) device modulates two optical carrier signals with the delayed and non-delayed input signals, respectively, separating the modulated delayed and non-delayed input signals into multiple time-concurrent frequency channel signals. Upon exiting the Bragg cells, the two optical beams interfere spatially to develop an interference pattern along the phase and frequency channel number axes of a photodetector array. The resulting spatial intensity pattern phase variation is decoded to provide coarse frequency, phase, and amplitude measurements. A frequency encoder receives the photodetector outputs, corrects phase and amplitude data offsets, and converts phase to fine frequency. Finally, the frequency formatter concatenates coarse to fine frequency for readout.
An apparatus for and method of calculating an integrated index of a transparent, translucent or opaque material for a desired wavelength range, the method comprising measuring a filtered value of the material as a function of wavelength within the desired wavelength range and calculating a protection index from the measured filtered value. The integrated index is used to quantify the ultraviolet, infra-red, erythemal or aphakic exposure properties of the material. In addition, the integrated index is used to quantify the photopic and/or scotopic response capabilities of the material. Further, the integrated index is used to quantify the differential or mean color indices of the material in comparison to the color spectrum or another material. Moreover, the integrated index is used to quantify the heat flux absorbed by the material.
