DE2165690A1 - A method of fixing an optical window in an electric discharge tube and a discharge tube provided with an optical window fixed by this method - Google Patents

Description

Arte Να. · PHU- 5509
dated December 29, 1971

Ancestors of defesting an optical window in an electrical one:; ntladuiifi ;? ^: tube and discharge tube provided with an optical window attached by this ancestor,

Dia . ', Rfinrlun ;; · refers to a method for _ie Testi j ^ en nines optical power in an electrical' r 1 1 a.'liiii. ^ Flröhre, bei>.'-.? Ni this Γ '.- nsfcer during the Ausholzii.i, »; the lintire is firmly soldered into place by means of a soldering material, because the melting temperature is lower than the temperature at which the tube will go out

'Furthermore, I relates the invention to a

oloktri ave LntladLiii £ j ^r ; tube with an optical window made by this method ".

BATH

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It is known to bring optical fans in electrical discharge tubes, in particular photographic pre-multipliers, whose jurclilitsci ^ kait to the Strnhijinf; is adapted, 'the nan zu ei.ipfr.ngen ^ ain cht, Zo = 5inl f'hotoverviolfac-ierröhren known, dia ir .: ultraviolet range (Y> q ± ' elLünlSngen of "about 1G00 K2) work and dis with optical windows between the expansion coefficients of the material :; of the window and dos i'a t '± ri-ils dos piston' 1er ib'hre b - there is usually a big difference, vodurcL os no tv . * o ·· ·· .. i _t ^ i; t, the window Nittel Ainet hdctilen Netcrials on the piston to attach the tube to this da.ait 'else UNTC rschi'jdo Ausdelinung in the window of the i.uri Soldering material commonly used for this "awake" soldering material: i al, with which a satisfactory vacuum-tight seal is obtained between the optical window and the bulb of the tube, because of the relatively high melting point (450 ° C) the tube can also be heated to a temperature of up to 300 ³ C of this material s are heated while the two sides of the optical window are different. Pressures are exposed.

However, the use of silver chloride indicates the The major disadvantage of this soldering material is that the use of bi- or Triallcaliphotocathodes, which are visible from the Range up to the middle of the ultraviolet range (up to Wavelengths of 1200 Aß) are not permitted, because such photocathodes are particularly fast from this Silver chloride released chlorine are attacked,

209834/0632 bad original

The invention aims to provide a method of the initially to create the old way of doing things, avoiding the disadvantageous part

For this purpose, in the method according to the invention, the optical Fonstor is soldered to its socket during the heating of the tube, the soldering material, the melting temperature of which is lower than the heating temperature of the tube, with a previously as a thin layer on the surfaces of the window to be soldered to one another and the fitting attached lietall forms an alloy, and during this soldering process the pressure nu ^? . the inside of the window is kept equal to the pressure prevailing on the outside of this window,

It is obvious that equal pressures on the b-ri'ion »sides of the window are absolutely necessary in order to prevent the soldering material from being removed during the soldering process. It is known that this equality of pressures can be obtained by placing the entire tube in a vacuum space. Another possibility is to connect the side of the opening of the window facing away from the piston of the tube to a connection to provide tuck, with the aid of the aforementioned versions will be connected to a vacuum bell ^kan:: in this ".. 'else is in front of the bake of the tube, the pressure on the a \ is sens exte the window equal or approximate de ^1! pressure prevailing inside the tube.

In the process according to the invention, indium is preferably used as the soldering material because this.

209834/0632 BAD original

Metal is very ductile, has a low melting point (15 ° C) and has a very low steam pressure.

.Dine particularly firm and vacuum-tight. Sealing between the window and the socket is obtained by that the surfaces of the mentioned parts to be soldered together are coated with a thin layer of a metal with which the indium can form an alloy. at Application of such. Layer that in one embodiment according to the invention by gilding the with each other surfaces to be soldered is obtained, it is also avoided that the indium during the heating of the tube flows out too much, so that the indium layer still has a sufficient thickness to, without moving from its To tear loose the subsurface, to compensate the mechanical tension, the temperature changes due to the difference between the expansion coefficients of each other soldered parts occur.

Although the method according to the invention: not limited to this, it can be particularly beneficial in mounting optical windows in photomultiplier tubes used, especially in those photomultiplier tubes which are provided with bi- or trialkaliphotocathodes.

Some embodiments of the invention are shown in the drawing and are described in more detail below. Show it:

. 1 shows a longitudinal section through a photomultiplier tube, with a by the invention

209834/063? "" ° ^R ' ^{G / NAL}

Method attached optical. Window is provided, Fig, 2 is a longitudinal section through something

modified embodiment of the version of the window after Fig. 1, and

Fig. 3 shows a longitudinal section through an embodiment of a socket for an optical window, - the Λαschltis5tück, with the help of which you can use a Vacuum bell can be connected.

In Fig. 1, "made of an iron-nickel-cobalt alloy produced version of the optical window consists of an annular hollow body 1, the cylindrical cavity 9 widens towards atissen and forms a cylindrical recess 3, Tn this recess 3 resting the magnesium fluoride window ö on the circular shoulder 5 provided with a circular groove h . Before the window is arranged on the shoulder 5, the surfaces of the shoulder and the window to be soldered to one another are coated with a thin layer of gold at the soldering point, after which indium wire is attached in the limie 4, the diameter of which is equal to that of the groove int,

After the window 6 has been placed in the recess 3, the socket 1 is housed in a vacuum chamber together with the piston 10 of the tube, in which the Dynocl system 11 has meanwhile been installed. Then, the tube is degassed for a few hours at a temperature of 300 ° C, while "ch the on both sides of d '; s Feiiriters prevailing same pressure is ensured dari.y the molten indium at this temperature

BATH ORIGINAL 209834/0632

remains in my place. After the tube has been sufficiently degassed, it is cooled down, the window being vacuum-tightly soldered in its socket, finally in the same. Vacuum space ufgedampft ε-the photocathode, after which the tube sealed vacuum-tight The letzters operation is _t is that the fitting 1 to a likewise made of an iron-Mickel cobalt Legionmg socket is set, one side of the piston 10 verlÖte- t and the other side of which has a ring 7 which is provided with a V-shaped groove 12 filled with indium the indium located in the groove 12 is pressed »

When the tube is closed, the Yef drive according to the invention can also be carried out in such a way that the groove 12 and the edge 2 are gold-plated and the two parts are soldered together with the aid of indium attached in the groove 12.

FIG. 2 shows a slightly modified embodiment of the socket according to FIG. 1. The modification consists in the fact that the diameter of the recess 3 is only slightly smaller than that of the piston of the tube; that the supporting edge 5 with the groove h made therein lies less deeply in the recess 3, whereby the top of the window is at the same or practically the same height as the top of the socket 1 ..

209834/0632 BATH ORIGINAL

Fi,;, 3 shows a further form of guidance in FIG

Socket for the window. In this case the socket consists of a metal ring 21, the hollow space 29 of which widens again and forms a recess 23 which contains a shoulder which is provided with a circular groove Pk . On the hand 27 of the ring 21, the thin-walled connection socket 2.6 is attached, the free end 22 of which can be connected to a vacuum bell. The ring 21 is attached with one side at 28 directly to the glass envelope 30 of the tube.

After the window and the photocathode vapor-deposited in a separate Valcuumrauni put in their place the tube is placed on a pump frame. But before starting the heating to degas the tube the pressures prevailing on both sides of the window are equalized and maintained, by connecting the socket 26 to the bell jar. After degassing, the tube cools down and becomes the window soldered to the shoulder 25 in the manner already described with reference to FIG. 1.

From the above-described embodiments goes shows that although it is obvious, in the frame of the window the cavity and the recess are circular cyuridrically to design, the application of the invention does not apply to a specific shape of the cavity and / or the mentioned recess limited,

BATH ORIGINAL

209834/0632

Claims (3)

PATENT CLAIMS: 1 , J method of fixing an optical window in an electrical. Discharge tube in which this window is soldered in its socket while the tube is being baked out with the aid of a soldering material whose melting point is below the temperature at which the tube is baked out, and during which the inside and outside of the window merge are exposed to the same pressure, characterized in that before the application of the soldering material, the surfaces to be soldered together of the window and the socket are coated at the soldering point with a thin layer of a metal that forms an alloy with the soldering material during the heating of the tube. 2. The method according to claim 1, characterized in that that the solder is made of indium, and that the on The metal layer attached to the surfaces to be soldered together consists of gold. 3. Electric discharge tube in which an optical Window is attached by the method of claim 1 or 2. H. Electric discharge tube according to claim 3j, characterized in that this tube is a photomultiplier tube provided with a bi- or trialkaliphotocathode. BAD ORiGiNAL 209834/063? Blank page