DE1798010A1 - Device for displaying and / or measuring the thickness of a thin coating on an object - Google Patents

Description

Device for displaying and / or measuring the thickness of a thin coating on an object

The invention relates to a device for displaying and / or Measuring the thickness of a thin coating on an object by means of radiation «,

The use of beta radiation to measure thickness / of thin coatings on objects or thin films is a well known technique and there are a number of devices employing this technique called "measuring tables" available in the stores. These measuring tables are of essentially the same construction and usually exist from a beta radiation source (a beta emitter), a device for displaying beta radiation and a measuring table top provided with an opening »One

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Display device is arranged in a housing whose upper surface can accommodate the measuring table plate such that the presence in the measuring table plate opening AMSTEL immediately above the fftrahlungsempfindlichen measuring surface of the display device there ^- are taken measures to ensure that the beta emitter between the opening and the display device and otherwise it is attached directly above the opening in some measuring tables, both arrangements being such that the opening, the radiation-sensitive measuring surface of the display device and the beta emitter are arranged on an essentially straight line ο

If a coating of a surface of a sample is to be measured, the surface is in contact with the plate Position attached so that part of the surface of the sample is above the opening in the measuring table top, while the surface rests against the edges delimiting the opening »The presence of the for this use between the display device and the opening provided beta radiator causes part of the inside of the container facing exposed surface through the opening is irradiated with beta particles ο each of the on the exposed area of the object impacting beta particles can be a) backscattered, b) absorbed, c) converted into another form of energy or d) let through.

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The number of backscattered beta particles, doh. the Number of beta particles emerging from the same surface that they entered is essentially a puncture of the atomic number of those under fire Carrier substance. Hence the backscatter obtained is from a coated surface a puncture of the thickness of the coating, the atomic number of the "coating forming" Material, the thickness of the carrier material and the atomic number of the carrier material ο The intensity of the backscatter for a given material increases steeply with thickness until a limit value of the thickness is reached. This thickness is referred to as the "saturation thickness" provided that the coatings to be measured are thinner than this saturation thickness and on a different from the coating material Base or carrier material are applied, the intensity of the backscatter is proportional to the thickness of the coating or the coatings from a given coating material » The intensity of the backscatter is measured by the display device, the output of which is usually is fed to a digital reading device »

The measuring tables of the type described above have the disadvantage that the shape and size of the opening depend on the shape and size of the object,

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whose coating is to be measured »Furthermore, if layered an object γοη of irregular shape and the coating has now been measured at various points on the surface of this test piece the use of an opening with a single size and a single shape is often insufficient » As a result, precautions are taken with these measuring tables to avoid an existing one on the table Exchanging the measuring table top for a measuring table top that has an opening of a different size and / or other form has ο This exchange of the Measuring table tops are not only time-consuming, but also increases the risk that the operator will Beta radiation is exposed ο This risk of exposure can be partially counteracted by for the A "Perspex" lid is provided on top of the measuring table is, in which there is an opening, through which manipulator tongs to exchange the Measuring table tops can be operated. Providence however, this lid further delays the transition. from measuring an area or part of a surface to measure another area or another part of the surface *

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According to the invention, a device for displaying and / or measuring the thickness of a thin coating on an object The help of radiation generated by means of a radioactive source is proposed »which is characterized by this is that there is a radioactive source, radiation-sensitive measuring equipment, a radiation shield with a Radiation window delimiting opening, a measuring table top with at least two openings and means present therein has to adjust and fix the measuring table top so that one or the other of their Openings with the radiation window covers, the arrangement being such that when the object is in against the plate in the adjacent position is in a position such that at least part of the coated Surface of the object that covers the openings with the radiation window, radiation from the source is directed at the area of the surface of the object delimited by this opening and the backscattering is determined from this area by the radiation-sensitive measuring equipment o

In the drawing, an embodiment of the subject matter of the invention is shown _o They show:

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Fig. 1 is a plan view of an apparatus for measuring the thickness of a thin coating on a Object using beta radiation,

FIG. 2 shows a side view of the device according to FIG. 1 with the omission of part of its box-shaped frame,

Figure 3 is a side view of a detail according to a partial section along the line III-III and Figo 1 and

Figo 4 shows a section through a further detail,

The measuring device shown consists of a box-shaped housing 1, which is made of beta radiation shielding material, such as ZoBo aluminum, and consists of two end walls 1a, two side walls 1b, an essentially square bottom wall 1c and an upper 7 / and 1d ο each The side walls 1b consists of a substantially rectangular plate, the thickness of which is sufficient to prevent the passage of beta radiation through the plate, a "Perspex" window being built into at least one of the side walls. Each of these side walls can be attached by means of screws attach one edge of the base plate 1c »

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Each of the end walls 1a consists essentially of one square metal plate, which are each provided with a substantially central opening through a flange Te is delimited in the opposing surfaces of the plate forming each end wall to create a partially spherical inner surface for the opening for the purpose explained in more detail below. Every Side wall Tb and each end wall 1a is at its upper edge provided with an inwardly directed flange to hold the also made of a radiation shielding material formed and provided with a central circular opening 2 (Pig. 1) delimiting a radiation window 1do The top 1d is attached to the at the top of the End and side walls of the housing provided, according to inwardly facing flanges fastened with screws

The upper part 1d carries a measuring table, which consists of a circular plate 3 consists of eight separately arranged openings 4, each one formed in it have a different shape or shape and around the plate 3 arranged around about the middle of the radial distance between the outer circumference and the center of the plate are ο The measuring table top has a hadius that is sufficient is so that it reaches over and covers the radiation window 2 in the upper part 1d of the housing, and is with respect to

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the upper part of the G-ehäuses with the help of a through the Center of the plate forming the measuring table top protruding and into the upper part 1d of the housing at one on the outer circumference of the radiation window in the upper part of the housing adjacent point screwed screw 5 rotatably attached, wherein for easy rotation of the measuring table plate relative to the housing between the underside of the measuring table plate and the top of the upper part of the housing an washer or washers are inserted. The one through the measuring tabletop 3 uncovered part of the top of the upper part 1d of the housing is covered by a further cover layer for the Radiant material of the same thickness as the measuring table top, which is at the top of the housing a Continuation of the top of the measuring tabletop forms »

The individual openings 4 in the measuring table top 3 are surrounded by a frustoconical part protruding from the top of the table top. The opening runs through the measuring table top and the frustoconical Part 3a, the size of the opening being delimited by the upper edges of the inner walls of the opening, which point towards on the. Diverge to the bottom of the opening. the end

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one arranged over the top of the actual opening Surface to a maximum radiation backscatter enable. The eight separately arranged openings 4 are formed around the measuring table top, each opening has a different shape or shape * the in this example the following are:

1. Circular opening with a diameter of T, 19 mm 2ο Circular opening with a diameter of 1.59 mm 3 ο Circular opening with a diameter of 3.17 mm 4o Circular opening with a diameter of 4.76 mm 5o rectangular opening with Sides of 0.38 x 6.35 mm 6o Rectangular opening with sides of 0.64 χ 6.35 mm 7 · Rectangular opening with sides of 0.89 x 6.35 mm 8. Rectangular opening with sides of 1.14 x 6.35

The dimensions of the openings refer to the top the opening *

The perimeter edge of the table top is sixteen in mutually evenly spaced notches 6 of spherical shape arranged separately from one another,

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while the adjacent edge of the cover layer of the housing is provided with a horizontal blind hole for receiving a compression spring which acts on a spherical ball in the hole to the outside to form a ball lock. The adjustment notches 6 are arranged around the circumferential edge of the circular plate forming the measuring table top 3 so that in each case one of the notches is arranged on the radii of the plate which run through the center of an opening 4, the remaining adjustment notches each being arranged between these notches are that a total of sixteen around the peripheral edge of the measuring table plate around separated from each other arranged in the same mutual spacing notches 6 formed _o If on the upper part 1d of the housing in the working position arranged measuring table plate 3, the ball detent in one of the existing in the measuring table plate Einstelleinkerbungen 6 engage, in order to arrange the measuring table top in such a way that one of its openings 4 is located essentially in the center of the radiation window in the upper part 1d of the housing or so that this radiation window passes through a massive part de lying between adjacent openings 4 r measuring table plate 3 is closed »

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The radiation-sensitive measuring devices consist of one arranged in the housing 1 and carried by its base plate Geiger-Müller counter tube whose radiation ■

sensitive part under the radiation window 2 and is arranged under the measuring table top 3 ο The output ■ ■ ■ The Geiger-Müller counter tube is used to display the intensity of the radiation backscatter on a digital reading device connected. ™

In the opening of each end wall la is a radiation source holder 7 arranged, which consists of a spherical ball formed from "Bakelite" or brass, which through the partially spherical surface of the paddles 1e is held in the end wall 1a and with a substantially diametrical bore is provided which receives a brass tube 9, which extends through the ball and into the Housing extends into the opening, the tube in ^

the bore of the ball has clearance so that it can slide into can rotate with respect to the ball about its longitudinal axis. Of the Sphere section is having one on its inside Provided with a threaded hole whose axis is to the axis the main bore runs transversely through the ball and opens into the main bore, where they receive a grub screw can to fix the tube in relation to the sphere * The splash 1e in the outer surface of each end wall 1a

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is also with one to the partially spherical Surface provided substantially radial threaded hole, the to fix the ball 8 with respect to the end wall 1a also receives a clamping screw, the arrangement is such that the ball 8 and the tube 9, which are carried by the end wall 1a, form a universal ball joint, by means of which the pipe can be clamped in a desired angular position to the end wall.

The brass tube 9 has a central bore, the diameter of which is about a third of the outer diameter of the Tube is ο toward the front end 9a of the tube 9 arranged in the housing, the central bore is widened and open. The tube 9 carries at its front end one in the axial direction from the annular edge the front end of the tube protruding trunnions. There is a diametrically opposite this pivot pin locating pin protruding in the axial direction Trunnion carries one with respect to the locating pin and the tube swiveling brass washer which is attached to the pivot pin at a point near its outer circumference is hinged so that this cap forms a front continuation of the brass tube 9 in the closed position to those from the enlarged part at the front end of the tube

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formed chamber to close. The cap is diametrical provided with a notch opposite this pivot pin, in which the protruding in the axial direction Locking pin can engage, the arrangement being such that a rotational movement of the tube about its longitudinal axis in with respect to the ball 8 in the end wall 1a of the housing 1 causes or allows the pivot pin to be in an arc around the longitudinal axis of the tube 9 upwards moves and the cap is adjusted under the action of gravity so that it closes the front end of the tube, until the notch with the - to the front - protruding Eestle pin engages to the cap opposite the chamber in the closed position keep. To open the front end of the tube, the tube is opposed with respect to the ball Direction rotated so that the cap moves away from the Pestle pen and the pivot pin moves around the axis describes an arc around the pipe until it is in its lowest position, in which the chamber is open at the front end of the tube »

The rear end of the brass tube placed in the ball 9 is diametrically opposed to each other with two each receiving a grub screw, extending in the radial direction arranged G-thread holes.

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The axial bore of the tube carries one in the tube displaceable elongated rod 10, the rear end of which is provided with a handle forming a rear stop is, while the front end of the rod 10 carries an axially extending pin 11 (Pig. 1 and 4), the at its front end a radiation source, in the present example a beta radiation source, carrying

having φ platform 11a, the arrangement being such that the elongated rod 10 is displaceable in the tube 9, so that when the rod is in the front position, the radiation source outside the chamber formed by the front end of the brass tube 9 and in the vicinity of the radiation-sensitive Measuring device and / or the radiation window is held while the source with the rearward position of the rod in the chamber in the front end of the brass tube The rod 10 can be accommodated in a front or rear position or in any position

"between these two positions with the help of the one in the rear Clamp the end of the brass tube arranged in the bore, diametrically opposite grub screws. By providing two radiation source holders, one in each end wall of the housing 1, one has a selection of beta emitters for use in the device »

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An in its wall -a axial slot exhibiting cylindrical plastic tube is arranged so that it can be disposed around the slidable in the tube of the radiation source support rod when the latter with respect to the tube in its rearward position befind et _t around the rod in in its rear position and to prevent unwanted forward movement of the rod with respect to the tube.

The bottom wall 1c of the housing carries a crane part that bridges the housing diametrically opposite the radiation window 2 » the one with a vertically arranged weight or spring loaded elongated retaining pin is provided, which is held by one arm of the crane part so that it is in arranged essentially vertically above the measuring table top 3 and can be adjusted to insert the sample into the to bring the correct position, with the end of the retaining pin coming into abutment against the table top With the help of a screw thread can be exchanged, the one to be exchanged Can hold pen tips of different geometrical shapes and made of different materials »

A Perspex safety pad can be arranged to fit around the retaining pin and cover the entire top of the device including the measuring table top ₉

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to provide additional radiation protection for the operator to accomplish.

During operation, the suitable opening 4 of the measuring table top 3 is selected and brought into line with the radiation window 2 in the upper part 1d of the housing, in that the ball lock engages in the matching adjustment notch 6 on the outer circumference of the measuring table top is to be measured, placed on the opening 4, and held in the desired position with the aid of a weight or spring-loaded retaining pin. Then the radiation source holder 7 is adjusted so that the beta radiation source to be used is exposed by. Setting up the relative front position between the rod 10 and the tube 9 and the position of the brass tube 9 in relation to the end wall 1a of the housing of the Beta - Emitter is arranged directly below the radiation window 2, so that the opening 4 in the measuring table top 3 »the beta radiation source and the measuring device of the Geiger-Müller counter tube are arranged on a substantially straight line _o When the desired position of the beta emitter is reached _r , the tube 9 is fixed in the ball joint with the aid of the grub screw provided for this purpose in the ball and the actual ball with respect to the end wall 1a with the help

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the clamping screw arranged in the puddle. The in the tube 9 displaceable rod 10 is with the help of each the grub screws acting on it in its matching Clamped position

The radiation from the beta emitter, which is in its working position, hits the coated surface of the through the opening irradiated specimen, wherein the Beta particles backscattered from the irradiated area are recorded with the aid of the Geiger-Müller counter tube and recorded on a Digital reading device can be recorded.

In practice it may be necessary to calibrate the device to a given coating material and to a given base material before routine measurements can be carried out. I ^{1 For} this calibration, the operation described above is carried out using a standard specimen from the desired. Base material is carried out with a known coating thickness and the reading is recorded on the reading device for the standard specimen Specimen is recorded again and then on

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logarlthmischein graph paper versus relevant Coating thicknesses applied and connected by a straight line. This causes the device to be calibrated for the particular aperture used and the beta radiation source used. For measuring the thickness of the coating material on the given base material, all you need to do is take a reading on the device and then the display panel to be used to determine the thickness of the coating from the reading of the digital reader.

If it is desired to change the opening 4, to interrupt the operation of the device or to close the device transport, the beta radiator can be withdrawn into the tube 9 by the one carrying the radiator elongated rod 10 is retracted, so that the risk of exposure to radiation for the operator is reduced o This retraction is not essential for the operation of the device, and normally when the opening is changed, the pulling in is every Emitter not necessary »If the opening 4 is to be changed, the measuring table top 3 can simply be used as long be rotated until the desired opening 4 is above the radiation window 2 in the upper part 1d of the housing 1 is located, whereupon the measuring process as described above can be repeated. If the device is to be transported or if the operation of the device is to be interrupted, the

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Measuring table plate 3 rotated about its axis until such a The circumferential notch 6 engages so that a part of the table top lying between two adjacent openings 4 engages covers the radiation window 2, while the beta radiator is withdrawn by retracting its elongated rod 10 so that it is housed in the enlarged front spherical section of the tube and the cap on the brass tube is closed in the manner described above.

It is clear that the device described after the The invention has advantages over the currently available devices and that the transition from an opening to another is considerably simplified and a considerable reduction in the risk of radiation for the operator by pulling the beta radiator into the one in the sphere held sleeve 9 is achieved. Furthermore, the position of the beta radiator in the actual housing can be changed, in order to adapt it to the test piece for which the radiator is used.

Patent claims;

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Claims (1)

Berlin, August 7, 1968 SEI-REX INTERNATIONAL S.A., Chatelaine-Geneve / Switzerland Patent claims (Pall 2) 1 · Device for displaying and / or measuring the pick of a thin coating on an object with the help of by means of a radioactive source of generated radiation, characterized in that it is a radioactive source, radiation-sensitive Measuring means, a radiation shield (1) with an opening delimiting a radiation window (2), a measuring table top (3) with at least two in it Has openings (4) and means (7) to adjust and fix the measuring table top so that one or the other of its openings coincides with the radiation window, the arrangement being such that when the object in the position against the plate (3) is in such a position that at least one -21-209810 / 0639 Part of the coated surface of the object with the openings that coincide with the radiation window (2) (4 ·) covered the radiation from the source on the through this opening is directed towards the delimited area of the surface of the object and the backscattering from this Area is determined by the radiation-sensitive measuring equipment. Device according to claim 1, characterized in that the radioactive source and the radiation-sensitive measuring equipment are stationary, while the measuring table top (3) adjustable and arranged in such a way that it fits into can bring at least two working positions in which the radiation from the source partially on the radiation-sensitive measuring equipment is backscattered o 3 »Device according to claim 1 and 2, characterized in that the measuring table top (3) circular and with a plurality of all at the same distance from its center arranged openings (4) and in their center to their rotational movement about a perpendicular to their plane Axis (5) is rotatably mounted so that each of its openings (4) in sequence in front of that in the radiation shield (1) existing radiation window (2) brought can be. 209810/0639 4 »Device according to claim 1, characterized in that each the openings (4) in the measuring table top (3) has a different shape or shape than each of the other openings (4) in order to enable the selection of a suitable one Opening for the surface to be examined- ^ u-enable " 5 * Device according to claim 1 and 2, characterized by a locking device for locking the measuring table top (3) in its various working positions, in which any of its openings (4) coincides with the radiation window (2), as well as in their positions, in which a massive part of the measuring table plate with the radiation window (2) coincides with it essentially to close and so when the device is not in use the To prevent radiation from escaping through the window (2) » 6 »Device according to claim 1, characterized in that the measuring table top (3) is made of radiation-shielding material 7. Apparatus according to claim 1, characterized in that the Radiation shielding from a radioactive source and the radiation-sensitive measuring equipment enclosing 209810/0639 ~ 23 - Housing (1) consists in whose upper wall '(Td) the Radiation window (2) is provided «* 8. Apparatus according to claim 1 and 7, characterized in that in at least one of the Seitenwäride (1 a) the Cover (1) an opening is provided to enable the operator to observe the underside of the radiation window (2) to enable and the setting of the object fP to facilitate the coating thickness of which is to be measured. Device according to claim T, characterized by a weight or spring-loaded pen pointing at the object whose coating thickness is to be measured, acts to make it against the measuring table plate (3) over one of its Create openings (4) and keep them in its correct position. 10 _o Device according to claim 1, characterized in that the radioactive source is a beta radiation source, while the radiation-sensitive measuring means consist of a Geiger counter tube. MB / Hi / Hf - 20 573 209810/0639 If Lee on the side