US 3343025 A
Description (OCR text may contain errors)
P 1967 J. R. IGNATOWSKI ETAL 3,343,()25
Patented Sept. 19, 1967 ELECTRON MULTIPLIER ARRAY FOR IMAGE INTENSIFIER TUBES James R. Ignatowski, Warren, and Robert R. Thornpson, Livonia, Mich. assgnors to The Bendix Corporation, Southfield, Mich., a corporation of Delaware Filed June 9, 1961, Ser. No. 116,189 3 Claims. (Cl. 313105) This invention is directed to electron rnultiplier arrays particularly for use in image intensifiers of the kind disclosed in United States Patent 3,128,408 entitled Electron Multiplier ssued to Goodrich and Wiley on April 7, 1964.
In that patent was disclosed an array of individual channel multpliers, each of which comprse a long tube or channel or relativcly small diameter, in the order of 001 inch, having a secondary emissive resstive coating on the interior surface thereof. Such an array might easily include 1,000 or more individual tubes. Ths invention provides a construction of such an array that is economical and eflcient.
It is therefore an object of this invention to provide an array of very small tubes or channels having an interior secondary emissive resstive surface that may be easily and inexpensively fabricated.
It is the object of this invention to form such an array utilizing corrugated sheets each having alternate ridges and grooves, with the surfaces of said sheets being secondary emissive and resstive; the corrugated sheets being alternated with flat sheets having secondary emissive resistive surfaces forming a plurality of channels between the corrugatons and the flat sheets.
It is a further object of this invention to coat the ends of these ridges and grooves with a conductive material such as a metallic paint so that a single voltage lead to an end of the array will place the corresponding ends of all the channels at the voltage value of the lead.
It is a further object of this invention to incorporate in the glass used for the corrugated and flat sheets cornpounds of materials, such as lead and bismuth, whch glass after reduction, as with hydrogen gas, provides a secondary emissive, resstive surface.
These and other objects will become more apparent when preferred embodiments of this invention are considered in connection with the drawings in which:
FIGURE 1 is a view of a preferred embodiment of this invention showing some corrugated sheets and flat sheets assembled and some in the process of assembly;
FIGURE 2 is an enlarged end of a corrugated sheet t illustrate the conductive layer on the end thereof, and
FIGURE 3 is an embodiment using only corrugated plates.
In FIGURE 1 is shown an array 20 having a flat sheet 22 as the bottom member thereof, a corrugated sheet 24 placed on top of flat sheet 22, a second flat sheet 26 placed on top of corrugated sheet 24, and so forth to form a stack of flat and corrugated sheets alternately placed one on the other. The flat sheets are tangent to the ridges of the corrugations to form individual channels between the lines of tangency. The two flat sheets on each side of a corrugated sheet thus constitute confining means for each of the corrugated sheets.
Both the fiat and corrugated sheets in the preferred embodiment have a glass body with a secondary emissive resistive coating on either side thereof such as tin oxide or antimony oxide. The glass in this ernbodiment is 001 inch thick and is heated uniformly and then sprayed with a mixture of .35 molar of S Cl 5H and 3.0 molar of SbCl to form a uniform resstive coating thereon. The resistance of the coating in this embodirnent is 1,000 megohms per square. Also, the resstive coating on the corrugated flat sheet may be formed thereon as the sheets are leaving the rolling mills.
After the array is completely assembled as by placing a sufficient number of alternate flat and corrugated sheets in a stack, the front end 28 of array 20 and the rear end 30 of the array 20 are coated with a conductive coating 31 (FIGURE 2) such as by painting with a conductive paint from a group of conductive paints which are commercially available. These paints would include gold, silver and platinum paints. Other methods of forming a conductive layer on the front and rear ends of the array include the vapor deposition of conductive metals with the vapor deposition occurring at a steep angle so that a minimum of the channel interiors would be coated with the deposited metal.
After the array is assembled, the sides of the corrugated and flat sheets are bonded at one side 32 and are bonded together at the opposite side 34 with an epoxy binding or may be fused together by heating locally to the melting point of the glass, or otherwise bound together.
A lead 36 is attached to the front portion 28 of the array and a lead 38 is attached to a rear portion of the array with a voltage source 40 being placed between leads 36 and 38. Since the front end 28 of the array is coated with a highly conductive material, the voltage of lead 36 will be applied to the front end of each channel and since the rear end 30 of the array is also coated with a highly conductive material, each channel end at the rear will be at the potential of lead 38. Ths forms a continuous potential gradient along each of the tubes or channels and sublies current to the surface of the channels for secondary emisson in accordance with the aforernentioned Goodrich and Wiley patent.
With a construction such as that shown in FIGURE 1, and with the glass thickness being about 001 inch and the height of the corrugations or ridges in a corrugated plate being about 008 inch, the ratio of the open te occluded area is about 7.3 to 1. This means that electrons or particles directed toward the array have a better chance of entering one of the tubes or channels rather than being absorbed by the conductive coating on the end of the array.
FIGURE 3 shows a second array having a plurality of corrugated plates 42 which are coated in the manner of plates 24 in the embodiment of FIGURE 1 to provide secondary emissive resstive surfaces, but whch array does not have the fiat sheets between corrugated sheets. Ths embodiment requires the alignment of the corrugated sheets so that ridges of one sheet supports the bottom of the grooves of the sheet placed on top of it. The size or diameter of the channels is twice as large as it is in the embodiment of FIGURE 1.
Instead of coating a glass with a secondary resstive coating as described, compounds can be added to glass during its manufacture which will provide it with a secondary emissive surface after hydrogen reductou. For example, if lead oxide and bismuth trioxide are added to the glass during its manufacture, the electrical conductivity of the glass surface will be increased to a predetermined desired point by reduction of the glass surface. One method of reducing the glass surface is to heat it to 325 degrees centigrade to 500 degrees centigrade for 8 to 16 hours and cause a flow rate of the hydrogen of about one liter per minute past the surface. A particular compound which has been shown to be efective for such use is 32% lead oxide, 61.3% silicon dioxide, 6.2 of barium carbonate and .5% of bismuth trioxde.
Although this invention has been disclosed and illustrated with reference to particular applications, the principles involved are susceptible of numerous other applications which will be apparent to persons skilled in the art. The nvention is, therefore, to be lmited only as indicated by the scope of the appended claims.
Having tl1us descrbed rny invention we claim: 1. An electrn multiplier array comprsing a plurality of insulative corrugated members and insulative confining means stacked one on the other to form a multdimerrsiorral array of open end covered channels, the nsulative material defining said open ends of said channels havng a highly conductive surface so that a single potential lead electrically connected with any one of said open channel ends will place all of the channel ends at a gven end of said array at the potential of said single potental lead, said corrugated members having a plurality of. grooves and ridges, said grooves having a secondary emissive resistive surface that is continuous from one groove end to the opposite groeve end, and said confinng means being placed adjacent said grooves and being fixecl t0 said grooves to form a covered channel open only at the ends thereof. 2. The electron multplier array of claim 1 wherein the corrugated members and confining means are fixed to each other by a borrdng of the side edges of said corrugated members to the side edges of the confining means whch extend longitudnally between opposte ends ofsaid array.
3. The electron multipler array of claim 1 wherein the insulatve eorrugated members comprise compounds of at least one of the elements of lead and bisrnuth, and said secondary emissive resistive surface comprising at least one of the elements of lead and bisrnuth.
References Cited UNITED STATES PATENTS JAMES W. LAWRENCE, Primary Examiner. J. W. HUCKERT, GEORGE N, WESTBY, Examiners.
V. LAFRANCHI, Assstant Examiner.