Патент USA US2406982код для вставки
Sept. 3, 1946. v. K. ZWORYKIN ET AL 23406382 ELECTRONIC VIBRATION DETECTING-APPARATUS Filed June 20‘, 1942 EI,’ .2, as w m5o M a wilI/ I a4 l WIM /a “r. LL ,5"M M Z! _. Y w ' J @Janux we)“ . 08.1 . . Gttomeg Patented Sept. 3, 1946 2,406,982 UNITED STATES PATENT‘ OFFICE 2,406,982 ELECTRONIC VIBRATION DETECTING APPARATUS Vladimir K. Zworykin, Philadelphia, Pa, and James Hillier, Cranbury, N. JL, assignors to‘ Radio Corporation of America, a corporationof Delaware ApplicationJuneZO, 1942; Seri'alNo. 447,864 9 Claims. (Cl. 1.77—-351) 1 This invention relates generally to vibration 2 vide a new and improved means for detecting detecting apparatus and particularly to vibra vibrations of extremely small amplitude. tion detection apparatus which utilizes. an elec— tron probe of extremely small cross sectional area which is-interrupted by a sharply de?ned mask ing. element responsive to the source of‘ vibra tions under observation. otherobj-ect of the invention is to provide‘ a new and improved means for detecting vibrations of An extremely small‘ amplitude in which the detection apparatus is substantially independent of thefre quency characteristics of the vibrations. Another object is to provide a new’ and improved means for detecting vibrations in a body, in which means dimensions of the elements of the. apparatus. 10 an electron probe of small cross-sectional area Suchv apparatus limitations have in most cases is interrupted by a movable’ element having a prevented the measurementof vibrations of am sharply de?ned edge responsive to the source‘ of plitude less than of the order of a micron- Since vibrations, and in which means‘ sec0ndary~elec by utilizing. the teachings of the electron micro tron responsive means is located in proximity to scope art, it is now possible to provide an electron ' the point of’ impingement of the electron beam beam or probe having a. cross sectional area of on the movable element. Still another object the order of I00 angstrom units, extremely sensi of‘ the invention is to provide a new and improved tive vibration detection apparatus may be con vibration detecting means, as described‘ hereto structed in. which such a concentrated. electron‘ fore, which includes means for generating‘, in beam is interrupted by a sensitive element con 20 dicating, and. recording‘ electric currents derived nected' to the. source of vibrations. from. the secondary‘ electrons emitted by the mov The instant invention includes a conventional able element‘ in response to the vibrations under electron gun. and electron focusing lenses of observation. either the electrostatic or electromagnetic types, The invention will be" described by reference to Heretofore, the sensitivity of vibration detec tion apparatus has been. limited by the phyiscal enclosed within arelatively heavy evacuated con tainer suitably supported to effectively insulate the unit. from the source of vibrations. The par the accompanying drawing in. which Figure I is a schematic diagram of one embodiment thereof; and Figure 2 is a view partly in section of a modi?cation of" a portion of the device shown in Figure 1. Similar reference numerals are ap ticular arrangement of the component elements of the electron. beam generating and. focusing elements may be as hereinafter described, or 30 plied to similar elements throughout the draw may- be of thev generalv type described by Manfred mg. Von Ardenne in U- S. Patent 2,257,174, granted Referring. to Fig. l- of the drawing, a heavy October 7., 1.941, for an Electronic-optical. device. evacuated casing l is supported on a suitable Asensitively balanced; and pivoted movable: ele frame 2 by means of‘ a plurality of expansion ment is supported by the heavy casing, and is springs 3,, to provide a substantially vibration arranged for contact with the source of vibra proof'mo'un-ting for the casing I. Within the cas tions. Through a suitable. S-ylphon. vacuum-tight ing, an electron sourced. is connected't'o a source of high. negative potential; derived from any suit enclosed. connection, within onetheend-vacuum of the chamber: movable in element the path able power source 26. An anode 5, which in of the ?nely concentrated electron probe, in such ~10 cludes a suitable aperture, and which is-at- ground a. manner that the electron beam falls upon a potential with respect. to the electron source 4-, sharply de?ned edge of the movable- element. In accelerates and. concentrates the electrons emit a preferred arrangement the sharply de?ned-edge tedlfromthe electron source into a. suitable beam. of the movable element is highly secondary A series of electron. lenses. 6,‘! and. 8, of the gen electron emissive, and suitable secondary-electron eral type utilized in electron microscopes, focuses responsive apparatus is associated therewith. for the electron beam passing through the aperture indicating the interruption of the electron beam in the anode 5 into‘ an. electron beam or probe in response to the vibrations under observation. having extremely small; cross-sectional area- It The particular arrangement ofthe component shouldv be. understood thatv the lenses 6,, 1- and 8 elements of the secondary-electron. responsive ap bi) may‘ be-of either the electro-magnetic or electro paratus may be of. any type. well known- in. the art, static types, and‘ may be‘ of the type employed in or as described in. the. copending application. of the electron: microscope art. James Hillier, Serial. No. 445,181’, ?ledi May 30-, A. bracket. 9 is connected to the evacuated cas 1942,.describedhereinafter. ing I. through- a-hinge' member In. A‘ movable " Among the objects of the invention are to pro lever element I l is pivoted at the extremity of the 2,406,982 3 bracket 9. The lever element II includes a con 4 electron probe. For most e?icient operating a carefully prepared contacting surface 25 should tact element for contact with the source of vibra be provided for the vibrating body I4 at the point tions. A Sylphon vacuum-tight connection I2 is of contact with the movable lever element I I. It sealed to the remaining arm of the lever member should further be understood that additional me I I to permit movement of the lever member with chanical modi?cations may be provided in the in the evacuated casing I. The extremity I3 of structure of the lever or contact element, and for the lever member II within the casing I, ter locating and adjusting accurately the position of minates in a knife edge preferably having sub the casing I and the movable element II with stantial secondary-electron emission character istics. This knife edge is normally disposed in 10 respect to the vibrating body I4 without departing from the spirit and scope of the invention. the path of the ?nely concentrated electron probe in such a manner that vibrations transmitted, for example, from a body I4 through the lever mem ber I I will cause interruption of the electron beam or probe by the knife edge I3 at the frequency of the vibrations. The lever member should preferably be made as small and light as possible, in order to provide satisfactory operation for vibrations of below the desired maximum fre quency. For the purpose of adjusting the initial position of the knife edge I3 in the path of the electron probe, a screw type adjustment I5 may be provided for the hinge bracket 9 and another screw type adjustment I6 may be provided for adjusting the position of the Sylphon I2 sealed to the lever element I I. In the path of the ?nely focused electron beam is a ?uorescent screen I'I, having an aperture It to permit the electron probe to penetrate the screen to the knife edge I3 of the movable ele ment II. Secondary electrons emitted from the knife edge I3 are attracted to the ?uorescent screen II, which is at a potential more positive Fig. 2 is similar to Fig. 1 with the exceptions that a solid ?uorescent screen 28 is used instead of the apertured screen ll of Fig. 1, the accelerat ing screen 21 is omitted and the knife edge I3 of the movable elever element II interrupts the elec tron probe at a point between the third lens 8 and the solid ?uorescent screen 28. Accordingly the solid ?uorescent screen is responsive to the pri mary electrons of the electron probe which are not interrupted by the movable element knife edge I3. Otherwise the operation and construc tion is similar to that of the device of Fig. 1. We claim as our invention: 1. An electronic device for detecting vibration in a body, said device including a relatively heavy evacuated envelope enclosing means for generat ing an electron beam, and means for deriving from said beam an electron probe of small cross sectional area, a movable element having a sharp ly de?ned edge enclosed within said envelope re~ sponsive to said vibration of said body, means for focusing 'said electron probe at said edge of said element, and means including electron responsive than the electron source 4 and the grounded cas ing I, due to a positive potential applied to a 35 means enclosed within said envelope responsive to said movement of said edge of said element for screen 2‘! surrounding the ?uorescent screen. Im deriving an electric current of amplitude propor pingement of electrons on the ?uorescent screen tional to a function of said movement. I‘! produces ?uorescence thereof which is imaged 2. An electronic device for detecting vibration by an optical lens I9 sealed in a suitable window in a body, said device including a heavy evacu in the evacuated casing I, upon a light sensitive able container, vibration insulating means for device 20 supported in proximity to ‘the lens. The supporting said container in proximity to said light sensitive device 20 may be either a photo body, means for generating an electron beam and electric cell or an electron multiplier of any suit means for deriving from said beam an electron able type well known in the art. The output of the light sensitive device 20 is connected to the 4-5 probe of small cross-sectional area, a movable element having a sharply-de?ned secondary elec input of an amplifier 2I designed to amplify effi tron emissive edge enclosed within said container ciently the frequencies to be observed. The out responsive to said vibration of said body, means put of the ampli?er 2| is connected, through a for focusing said electron probe at said edge of switch 22, to either a cathode ray oscilloscope 23 or a recorder 24. It should be understood that 50 said element, means for collecting secondary elec trons from said edge of said element and a, ?uo the characteristics of the indicator 23 and the re rescent screen enclosed within said container, corder 24 may be suited to the particular type of means for applying said secondary electrons to indication or recording desired, and that the par said screen to produce ?uorescence thereof, and ticular apparatus may be of any type well known light responsive means for deriving an electric in the art. current proportional to a function of said ?uo The electron focusing lenses are adjusted to rescence. provide an electron beam of the smallest possible 3. A device of the type described in claim 2 in cross-sectional area at the point of impingement cluding current indicating means, and means for of the electron beam with the knife edge I3 of the movable element I I. If the casing I is supported 60 applying said derived current to said indicating means. in proximity to the vibrating body I 4, the bracket 9 is adjusted by the adjusting device I5, and the movable element II is adjusted by the adjusting device I6, so that the knife edge I3 just inter 4. A device of the type described in claim 2 in cluding current recording means, and means for applying said derived current to said recording sects the electron beam when no vibrations are means. ' 5. An electronic device for detecting vibration transmitted to the movable lever element I I. in a body, said device including a heavy evacuable Since the sensitive movable lever element pro container, vibration insulating means for sup vides a leverage of several times, it is apparent porting said container in proximity to said body, that the most minute vibrations applied to the lever element II will completely interrupt the 70 means for generating an electron beam and means enclosed within said container for deriv electron beam at the frequency of the vibrations ing from said beam an electron probe of small from the source I4. It should be understood, cross-sectional area, a movable element having a however, that a lever type vibration transmitting sharply-de?ned secondary electron emissive edge element is not essential, and that any other sensi enclosed within said container responsive to said tive means may be provided for interrupting the 5 2,406,982 6 vibration of said body, means for focusing. said electron probe at said edge of said element, means for collecting secondary electrons from said edge of magnitude proportional to a function of said movement. 8. An electronic device for detecting vibration of said element, a ?uorescent screen enclosed in a body, said device including an evacuated en velope enclosing means for generating an elec within said container, means for applying said secondary electrons to said screen to produce ?u orescence thereof, and light responsive means in— cluding a photo-electric device and an ampli?er connected to said photoelectric device for deriv tron beam, a movable element responsive to vi bration of said body, said element having a sharply-de?ned movable edge enclosed within said envelope, means for focusing said beam to ing an electric current proportional to a function 10 provide an electron probe of small cross-sectional of said fluorescence. 6. An electronic device for detecting vibration in a body, said device including an evacuated envelope enclosing means for generating an elec tron beam, a movable element responsive to vi bration of said body, said element having a area impinging upon said edge of said movable element, means for collecting secondary elec trons from said edge of said element in response to said impingement of said electron probe there on, and means including secondary electron re sponsive means enclosed within said envelope re sharply-de?ned movable edge enclosed Within sponsive to said movement of said edge of said said envelope, means for focusing said beam to element for deriving an electric current of mag provide an electron probe of small cross-sectional nitude proportional to a function of said move area impinging upon said edge of said movable ment. , element, and means including electron responsive 9. An electronic device for detecting vibration means enclosed within said envelope responsive in a body, said device including an evacuated en to said movement of said edge of said element for velope enclosing means for generating an elec deriving an electric current of magnitude pro tron beam, a movable element responsive to vi portional to a function of said movement. 25 bration of said body, said element having a '7. An electronic device for detecting vibration sharply-de?ned movable edge enclosed Within in a body, said device including an evacuated en said envelope, means for focusing said beam to velope enclosing means for generating an elec provide an electron probe of small cross-sectional tron beam, a movable element responsive to vi area impinging upon said edge of said movable bration of said body, said element having a 30 element and providing secondary electron emis sharply~de?ned movable edge enclosed Within sion therefrom, a ?uorescent screen enclosed said envelope, means for focusing said beam to within said envelope, and means for applying provide an electron probe of small cross—sectional said secondary electrons to said ?uorescent screen area impinging upon said edge of said movable to provide ?uorescence thereof proportional to element, and means including electron respon 35 a function of said movement of said edge of said sive means enclosed within said envelope respon element. sive to electrons of said probe passing said edge of said element for deriving an electric current VLADIMIR K. ZWORYKIN. JAMES I-IILLIER.