摘要:
A device for measuring a vibration frequency of a mechanically vibrating string (11) or rod (41), comprising a microwave transmitter (14) for directing microwaves towards the vibrating string and a microwave receiver (17) for receiving the microwaves amplitude modulated by the frequency of mechanical vibration. A member (18) is arranged close to a vibration maximum of the vibrating string. The member is arranged on one side of the vibrating object and the microwave receiver is arranged on the other side thereof. The device is used for measuring temperature, pressure, torque, force or identity.
摘要:
Vibrating resonant mechanical structures are excited optically by photokinetic energy transfer and detected optically. In particular, a tuning fork sensor measuring a physical parameter is excited into oscillation by radiant energy and the frequency of vibration is detected by radiant energy which may be communicated via an optical fiber. These vibrations are communicated via a fiber optic to a detection location.
摘要:
A sensor comprises a beam 1, e.g. of silicon, which resonates at a frequency dependent on the force imposed on the beam. Light on line 11 induces resonance of the beam 1 by means of the photothermal effect. The light reflected from the beam 1 is amplitude modulated at the resonance frequency, and returns along line 11. It is reflected by semi-reflecting plane mirror 17 onto lens 19 which focusses it onto photodetector 20. Photodetector 20 produces an output voltage modulated at the oscillation frequency, and is thus representative of the force imposed on beam 1.
摘要:
A sensor comprises a beam 1, e.g. of silicon, which resonates at a frequency dependent on the force imposed on the beam. Light on line 11 induces resonance of the beam 1 by means of the photothermal effect. The light reflected from the beam 1 is amplitude modulated at the resonance frequency, and returns along line 11. It is reflected by semi-reflecting plane mirror 17 onto lens 19 which focusses it onto photodetector 20. Photodetector 20 produces an output voltage modulated at the oscillation frequency, and is thus representative of the force imposed on beam 1.
摘要:
Des structures mécaniques résonantes vibratoires sont excitées optiquement par transfert d'énergie photocinétique et sont détectées optiquement. En particulier, un capteur à fourche de syntonisation mesurant un paramètre physique est excité de manière oscillatoire par une énergie radiante et la fréquence des vibrations est détectée par l'énergie radiante qui peut être communiquée via une fibre optique. Ces vibrations sont communiquées à un point de détection via une fibre optique.
摘要:
Détecteur résonnant entraîné optiquement et à oscillation électromagnétique soumis à une force de tension, où l'énergie motrice optique et le signal communiqué optiquement produit en réponse à la force de tension sont tous les deux transmis à une distance considérable le long d'une seule fibre optique (14). Une partie de l'énergie d'alimentation (19) entraîne le mécanisme oscillatoire (20), et une autre partie est réfléchie vers un détecteur de fréquence (18) par l'action d'obturation de l'élément résonnant. Le dispositif peut être conçu de façon à être entraîné électriquement et détecté optiquement, entraîné optiquement et détecté électriquement, ou aussi bien entraîné que détecté optiquement ou électriquement, pour atteindre une versalité rétrospective maximale dans des systèmes de commande de processsus passés, présents et à venir.
摘要:
A strain or pressure responsive transducer comprises a pair of elongate beam resonators arranged end to end and provided with a flexible coupling therebetween. The arrangement oscillates e.g. in a double see-saw or butterfly mode. The transducer is disposed on a diaphragm whereby strain may be transmitted to the oscillatory system. The frequency of oscillation is a function of this strain.
摘要:
A vibratable element whose resonant frequency changes in accordance with an external source of variable applied pressure, has an inner cavity in fluid communication with the source of applied pressure, so that variations therein produce corresponding changes in the internal pressure of the cavity. Increases in this internal pressure cause the flexible walls surrounding the cavity to expand outwardly, thereby increasing the mechanical stiffness of the element. The increased stiffness produces a corresponding increase in the resonant frequency. Conversely, a decrease in pressure allows the walls to slacken and reduce the overall stiffness of the element. A linear relationship exists between changes in applied pressure and changes in the resonant frequency, over an appreciable range of pressures. An optical scheme detects the frequency, and conventional electronics correlate the frequency to the corresponding pressure, or to another physical variable represented by the applied pressure.
摘要:
The problem of providing a process control instrument employing a vibratable string (41) that is safe in explosive environments is solved by using a continuous gas stream or series of gas impulses through a port (59), such as a jet nozzle, to impinge on the string which has its tension and therefore its resonant frequency determined by a process parameter as sensed, for example by pressure in a bellows (25). Variations in the alignment between the port and string produce different modes of vibration, one being particularly suitable for process measurement. In one example, an optical sensor provides an intrinsically safe instrument for measuring the frequency of vibration.