A system is described for measuring the distance to an object by comparing a first component (18) of a light pulse that is reflected off the object (14), with a second component (20) of the light pulse that passes along a reference path (26) of known length, which provides great accuracy with a relatively simple and rugged design. The reference path (26) can be changed in precise steps so that is has an equivalent length approximately equal to the path length of the light pulse component that is reflected from the object. The resulting small difference in path lengths can be precisely determined by directing the light pulse components into opposite ends of a detector (70) formed of a material that emits a second harmonic light output at the locations where the opposite-going pulses pass simultaneously across one another.
A programmable fiber optic delay system employs multiple programmable fiber optic delay lines, and switches among the delay lines for inclusion in an overall delay path. Switching among the delay lines is coordinated with the programming of those lines so that only a delay line with a settled delay program is included in the overall delay path. Each delay line consists of a plurality of fiber optic segments of varying length. The line's delay is programmed by switching in particular segments whose aggregate lengths correspond to a desired delay period. The multiple delay lines are used to simulate target speed and distance for use in testing a radar system. The programming of each individual delay line and the switching between lines is preferably controlled by a computer resident in the target simulator.
Distance measuring apparatus and method using a pulsed electromagnetic wave for making a high speed precise distance measurement between the apparatus and an object over a small distance. The electromagnetic wave is projected to an object from a single projector to provide a reflected electromagnetic wave from the object that is received by a single receiver also receiving a reference electromagnetic wave branched from the projected electromagnetic wave. The reference-wave reception time at the receiver is delayed by a delay time, so that a first time period between the electromagnetic wave projection time and the reference-wave reception time is longer than a second time period between the projection time and a reflection-wave reception time at the receiver. The distance is determined according to the delay time and the time difference between the reference-wave reception time and the reflection-wave reception time.
A laser beam type distance measuring device comprising a laser beam emitter; a laser beam receiver having a going laser beam sensor and a returning laser beam sensor; an electrical signal processing circuit connected to the going and returning laser beam sensors; a returning laser beam guide way leading to the returning laser beam sensor; a polygon mirror for reflecting a going laser beam from the laser beam emitter toward a remote object and reflecting a returning laser beam from the object toward the returning laser beam guide way along which the returning laser beam travels to the returning laser beam sensor; and a reference optical track having one end directed to the laser beam emitter and the other end directed to the going laser beam sensor, so that a first part of the going laser beam from the laser beam emitter travels to the going laser beam sensor through the reference optical track. In the present invention, there is further provided a laser transmitting member, such as an optical fiber, which is arranged in parallel with path to and from the object. The laser transmitting member has one end directed to the laser beam emitter and the other end directed to the returning laser beam sensor, so that a second part of the going laser beam from the laser beam emitter travels to the returning laser beam sensor through the laser transmitting member.
A distance measurement device that provides high speed and accuracy. A light divider separates pulsed light emitted from an ultrashort pulse fiber laser into reference light A and signal light. A scanning mirror unit irradiates an object with the signal light and receives scattered light B, which is reflected from the object. An optical path length adjustment unit adjusts an optical path length of the reference light A. A differential detector detects the degree of interference of the reference light A having the adjusted optical path length with the scattered light B and outputs the detected degree of interference as an interference signal. A computer specifies an adjustment value, set in the optical path length adjustment unit, to attain a specific optical path length maximizing the interference signal and uses the specified adjustment value to compute the distance from the scanning mirror unit to the object.
New apparatus comprise a optical fiber based RF signal train generator for storing transient RF pulses and regenerating the identical replicas for analysis. The apparatus further comprise RF receivers to process one stored pulse with a reference to other stored pulse. The present invention drastically increases our abilities to investigate acoustical, electromagnetic, and optical transient phenomena.
