US2894140A

US2894140A - Vertical industrial x-ray fluoroscope

Info

Publication number: US2894140A
Application number: US663427A
Authority: US
Inventors: Justin G Schneeman
Original assignee: Individual
Current assignee: Individual
Priority date: 1957-06-04
Filing date: 1957-06-04
Publication date: 1959-07-07
Anticipated expiration: 1976-07-07

Description

July 7, 1959 Filed June 4, 1957 J. G. SCHNEEMAN VERTICAL. INDUSTRIAL X-RAY FLUOROSCOPE 2 Sheets-Sheet 1 I INVENTOR. Jusmv 6. SGHNEEMAN y 7, 1959 J. G. SCHNEEMAN' 2,894,140

VERTICAL INDUSTRIAL X-RAY FLUOROSCOPE Filed June 4, 1957 2 Sheets-Sheet 2 uvwszvrox Jusrl/v 6 Sc/INEEMAN 4270mm vs United States Patent VERTICAL INDUSTRIAL X-RAY FLUOROSCOPE Justin G. Schneeman, Rivera, Calif.

Application June 4, 1957, Serial No. 663,427

4 Claims. (Cl. 250-62) This invention relates generally to fluoroscopic inspection apparatus, and more particularly to apparatus for fiuoroscopically inspecting. manufactured parts and assemblies.

In my Patent No. 2,683,812, issued July 13, 1954, and

entitled Fluoroscopic Inspection Apparatus, I have shown and described apparatus which is quite well adapted for use in the usual industrial applications of fluoroscopic inspection. This apparatus makes it possible to inspect a part which is larger than the fluorescent screen and viewing aperture, because the part-supporting means moves the part with respect to the screen thereby allowing the various portions of the part to be viewed individually. At the same time, the apparatus provides complete shielding of the part and radiation source for theprotection of the operating personnel.

Certain special applications have been encountered, however, with requirements that call for apparatus having additional capabilities. For instance, in certain applications it is desirable that the image produced by the apparatus have a particularly high degree of resolution; that is, be sharp and distinct.

As is well known to those skilled in the art, the resolution of an image is always hampered to some degree by the fact that. it is impossible, in practice, to produce a point; source of rays, and, as a result, rays from one part of the source strike a given point in the specimen at a slightly different angle than rays from another part of the source. The resolution of an image can be improved, however, by increasing the distance between the source of radiation and the specimen, and/or by decreasing the distance between the screen and the specimen, because this proportionately reduces the efiect of the angular discrepancies between the rays.

Therefore, in applications where a high degree of resolutionis required, apparatus is needed which is capable of effecting a substantial spacing between: the source and the specimen, while, at the same time, allowing the screen to be positioned in. close proximity to the specimen. Inspection apparatus knownand used prior tothis invention does not have suflicient capabilities in this regard.

Furthermore, experience in fluoroscopic inspection has shown that flaws in the parts or assemblies being inspected often show up better when the X-ray beam strikes the part at a certain angle of incidence. For this reason, it is quite advantageous, in applications where flaws are particularly difiicult to detect, to be able to vary the angle of incidence of the X-ray beam.

Also, special applications have arisen wherein it is necessary to. fiuoroscopically inspect very large parts or assemblies. This requirement is often encountered in the aircraft industry, for instance, where wing sections and other large assemblies require inspection. Apparatus, such as that disclosed in my Patent No. 2,683,812, referred to above, which moves the part being inspected in a horizontal plane, is not suitable for such inspection,

because horizontal movement of large parts, if contained within a shielded housing, would necessitate a housing of excessive floor space and make viewing by the operator through the vertically opening aperture quite diflicult.

On the other hand, if apparatus is designed which holds the specimen in a fixed position and scans it by moving the beam, provision must also be made for moving the screen and the operator viewing it, so that they remain in alignment with the beam. In addition, some means of shielding must be provided which allows such movement and still adequately protects the operating personnel. As a result, apparatus of movable beam type design is quite complicated and expensive. Suitable apparatus for the fluoroscopic inspection of large parts is therefore not easily achieved.

It is therefore a major object of this invention to provide fluoroscopic inspection apparatus which is capable of fulfilling all of the above-mentioned requirements for special applications.

It is also an important object of this invention to provide fluoroscopic inspection apparatus in which the axis of the beam of radiation is generally horizontal and the distance between the source of radiation and the specimen being. inspected may be varied while inspection is in progress and may be substantially increased when high image resolution is required.

It is another object of this invention to provide inspection apparatus of the character described in which the distance between the screen and the specimen being inspected may be varied to adjust the image presentation, and the radiation source may be tilted to change the angle of incidence of the beam on the specimen while inspection is in progress.

It is a further object of this invention to provide fluoroscopic inspection apparatus of the type described above which is capable of handling, as specimens, large parts or assemblies, and moving these specimens with respect to a substantially fixed beam of radiation, while, at the same time, providing adequate protection for operating personnel.

Still another object of this invention. is to provide inspection apparatus of the type described above in which the movement of the specimen being inspected is. poweroperated and can be controlled by the operator from aremote operating station, while inspection is in progress.

Still a further object of this invention is to provide inspection apparatus as described above in which different means for producing and recording images producedfrom the beam of radiation may be substituted by the operator, as desired, while inspection is in progress.

And yet another object of this invention is to provide fluoroscopic inspection apparatus of the character described which has a unitary construction, occupies a minimum of floor space, and is relatively inexpensive to manufacture.

These and other objects and advantages of this invention will become apparent upon a consideration of the following detailed description of a preferred embodiment thereof, read in connection with the accompanying. draw ings, wherein:

Figure l is a perspective view illustrating the general form, arrangement and appearance of a preferred embodiment of this invention;

Figure 2 is a cross-sectional view taken substantially along line 22 in Figure 1;

Figure 3 is a cross-sectional View taken substantially along line 33. in Figure 1;

Figure 4 is a fragmentary cross-sectional view taken:

substantially along line 4--4 in Figure 2;

Figure 5 is a cross-sectional View taken substantially along line 5-5in Figure2;

Figure 6 is a cross-sectional view taken substantially along line 66 in Figure 3;

Figure 7 is a cross-sectional view taken substantially along line 7 7 in Figure 6; V

Figure 8 is a fragmentary side elevation of an access door containing image-producing apparatus;

Figure 9 is a cross-sectional view taken substantially along line 9-9 in Figure 8, in which a dotted outline illustrates how the viewing apparatus may be repositioned; and

Figure 10 is a fragmentary side elevation of the inside of the access door shown in Figure 8. In general, fluoroscopic inspection apparatus contains these essential elements: a source of penetrating radiations, means for positioning the specimen to be inspected before the beam of radiations emanating from the source, means for producing an image from the beam after it has intercepted the specimen, and means for protecting personnel from the harmful effects of the radiation.

In the disclosed embodiment of this invention, the source of the penetrating radiations is an X-ray tube, but it could, of course, be some other suitable radiation source, such as a radioactive element or compound. The specimen support means comprises two powerdriven carriages adapted to move the specimen about in front of the beam of radiation emanating from the X-ray tube in a plane generally normal to the path of "the beam, so that the beam can scan all portions of the specimen. Thus, scanning of the specimen is effected in this apparatus by moving the specimen with respect to the radiation source. The means for producing an image constitutes a fluorescent screen positioned on the oppo- !site side of the specimen from the radiation source so that the radiation beam will intercept the specimen before striking the screen, and therefore produce an image of the specimen thereon, and the means for shielding the operating personnel from the radiations is a housing of material impenetrable to the radiations. Other imageproducing means are also provided and made interchangeable with the screen, as will be explained later. The housing completely encloses the aforementioned elements, yet, at the sarne time, makes provision for viewing of the screen by the operator, ingress and egress of the specimens, and control of the movement of the specimen support. Thus, all of the elements essential to fluoroscopic inspection apparatus are present.

Referring now to the drawings, and particularly to Figure 1 thereof, the reference numeral 10 indicates generally a housing which comprises two tunnelshaped portions joined to form a T in the plan View. The tunnelsshaped portion forming the top of the T is indicated by the reference character 11, and is referred to as the specimen tunnel, since it is designed to contain the part or assembly being inspected. The portion forming the leg of the T is designated by the numeral 12 and is referred to as the radiation tunnel, since it contains the source of radiation.

Each of the tunnels is rectangular in cross-section and has walls constructed of lead and/or other material impenetrable by the type of penetrating radiation to be used, in this case X-rays. The specimen tunnel 11 extends to the floor and is supported thereon by laterally disposed I beams 13. Channel irons 14 run up the face wall 15 of specimen tunnel 11 to give additional rigidity. Since, as will become apparent later, the radiation beam is directed toward the face wall 15, this wall has extra thickness in order to assure adequate shielding. An access door 16 containing image-producing apparatus used by the operator during inspection of the specimen is positioned on face wall 15 between the channels 14. The door 16 provides a convenient means of access to the central portion of the specimen tunnel 11 and is located at approximately eye level above the floor so that the image producing apparatus is positioned at a convenient height for an operator. The operators station for the inspection apparatus is the general area 17 in front of the access door 16.

In the right hand end wall 18 (in Figure 1) of the spec1- men tunnel 11, a specimen portal 19 is provided. The specimen portal 19 extends over the major portion of end wall 18 and is large enough to pass any part or assembly which specimen tunnel 11 can accommodate.

The radiation tunnel 12 is joined to the specimen tunnel 11 at the approximate center of the specimen tunnel back wall 21 (see Figure 3) and communicates with the specimen tunnel through an opening 21a. The radiation tunnel 12 is considerably less in height than the specimen tunnel 11 and therefore only extends part way to the floor. Legs 22 are provided to support the free end of the radiation tunnel. An access door 23 is provided in one side of radiation tunnel 12 to permit ready access to its interior.

To support a part or assembly and provlde means for moving it about for scanning by the radiation beam, the specimen tunnel 11 contains a specimen support 24 (see Figure 2) which comprises a vertical carriage 25 for moving the specimen up and down with respect to the beam and a horizontal carriage 26 for moving the specimen back and forth. The vertical carriage 25 extends longitudinally from one end of the tunnel to the other and has rollers 27 disposed at each end which engage and roll on vertical guides 27a mounted at each end of the tunnel. (See Figure 4).

To provide means for raising and lowering the vertical carriage 25, vertically disposed jack screws 28 are rotatably mounted adjacent each end of the carriage and are connected to the carriage by travel nuts 29 which travel up and down on the screws. The screws 28 are driven in unison through bevel gears 30 by a horizontally disposed drive shaft 31 which extends across the upper portion of specimen tunnel 12. The drive shaft 31 is rotated by a motor 32 which is also mounted in the upper portion of the specimen tunnel 12.

To counterbalance the weight of the vertical carriage 25 and thus reduce the load on motor 32, counterweights 33 are connected to the carriage by means of cables 34 and overhead mounted pulleys 35.

The horizontal carriage 26 of the specimen support 24, which provides for back and forth movement of the specimen, is mounted in piggyback fashion on the vertical carriage 25 and travels longitudinally in specimen tunnel 11. The horizontal carriage 26 travels on two rails, an upper rail 38 and a lower rail 39 (see Figure 5). The

rails

38 and 39 are disposed hon'zontally and in a longitudinal direction on vertical carriage 25 with the upper rail 38 positioned approximately in the center of the top of the carriage and the lower rail 39 approximately in the center of the bottom.

To engage these rails, the horizontal carriage 26 has guides 41 each comprising a group of three rollers. Two of the rollers 42 of the guides 41 are disposed for rotation in a horizontal plane and are spaced apart just enough to snugly receive the corresponding rail between them. These rollers 42 are called guide rollers because they guide the movement of the carriage. The other roller 43 of each guide 41 is disposed to rotate in a vertical plane and position to engage a horizontal surface of the rail. These rollers 43 position the carriage vertically between the two

rails

38 and 39 and are called main rollers since the main rollers in guides 41 engaging lower rail 39 carry the weight of horizontal carriage 26 and the specimen.

To provide means for driving the horizontal carriage 26 along the

rails

38 and 39, a rack gear 44 is positioned on one side of lower rail 39, and a drive motor 45, mounted on the horizontal carriage, is engaged with this rack gear.

Since the drive motor 45 is mounted on horizontal carriage' 26 itself and vertical and

horizontal carriages

25 and 26 are movable both with respect to each other and with respect to the housing 10, a special arrangement is necessary to. carry electric power 'conductorsrfrom the housing to the motor. This arrangement is provided by two spring-loaded take-up

reels

47 and 48, both mounted on the vertical carriage 25 (see Figure 2). The electric power is carried from an outlet box 49 on housing to the first take-up reel 47, which is mounted on the upper portion of vertical carriage 25, by a flexible electric cord 50. The second take-up reel 48 is mounted on the lower portion of'vertical carriage and connected to the first reel 47 by a solid conduit 51. A second flexible electric cord 52 is then used to connect from the second reel 48 to drive motor mounted on horizontal carriage 26. Thus, as vertical carriage 25 moves with respect to outlet box 49 on the housing 10, the first reel 47 pays out or takes up the flexible cord 50, asrequired, and when horizontal carriage 26 moves with respect to vertical carriage 25 and the

reels

47 and 48, carrying the drive motor 25 along, the second take-up reel 48 pays out or takes up the flexible cord 52.

The two

drive motors

32 and 45 which drive the two carriages of specimen support 24 are controlled by control means mounted on face wall 15 of the specimen tunnel 11. The control means 55 is within easy reach of the operatorsstation 17.

To mount a part or assembly on the specimen support 24, a fixture 56 is provided which can be made of material substantially transparent to the penetration of the particular radiation used, when necessary to avoid interference with proper viewing. Certain woods, resins, or

plastics are satisfactory for this purpose. Clamps 57 are provided on fixture 56 to hold the specimen in place.

To support the radiation source in the radiation tunnel 12, a yoke-shaped support frame 60 .(see Figures 3 and 6) is longitudinally disposed in the tunnel and pivotally mounted on trunnions 62 projecting from the sides thereof, adjacent the opening 21a into specimen tunnel 11. The major portion of the support frame 60 comprises two parallel arms 61 which extend rearward from the mounting trunnion's 62, and slidably, carry a holder 63 which holds the X-ray tube 64.

At their distal ends the arms are connected by a crossbar 65 and supported by a flexible cable 66 which passes through a pulley 67 attached to the top of the radiation tunnel. By means of additional pulleys 67a, the cable 66 is carried to a manual control reel (see Figure l) on the face wall 15 adjacent the operators station 17. By operation of the control reel 68, the operator may raise or lower the distal end of support frame 60, and thereby tilt the X-ray tube 64 to change the angle of incidence of the beam with respect to the specimen.

A rack gear 69 is disposed between and parallel to the arms 61 and in engagement with a drive motor 70 which is mounted on the holder 63. Operation of the drive motor 70 therefore causes the holder 63 to be moved along the arms 61 and carry the X-ray tube 64 toward or away from the specimen tunnel 11, thus regulating the distance between the specimen and the radiation source. Power and control leads to the X-ray tube 64 and the drive motor 70 are carried by the conduit 71 to their

respective control panels

72 and 73 on the face wall 15 adjacent the operators. station 17.

To produce an image from the beam of radiation after it has intercepted the specimen, a fluorescent screen 75 (see Figure 3) is provided on theopposite side of the specimen tunnel 11 [from the opening 21a and disposed in the path of the beam, which enters from the radiation tunnel 12. The screen 75 is carried by a yoke 76 which is pivotally mounted to the inside of the access door 16. The pivotal mounting of the yoke 76 is urged by a spring 77 (see Figures 8 and 9) to normally carry the screen 75 inwardly toward the specimen. To control the amount of inward movement, a cable 78 is attached to the yoke 76 and connected through the door 16 to a control lever 79 on the outside of the-door. By movement of control lever 79, the movement of yoke 76 may be controlled 6 and the screen 75 positioned as close to the specimen, as desired.

The screen 75 is pivotally mounted on pintles 80 at the free end of the yoke 76 so that it may be adjusted about a vertical axis to different angles with respect to the specimen. Thus, if the specimen has an uneven surface, the screen may be adjusted to the particular portion to be viewed. The access door 16 is convenient for making these adjustments.

To provide means by which the operator can view the screen 75, viewing apparatus is incorporated into access door 16. For this purpose, the access door 16 has an aperture 81 therethrough which is aligned with the screen 75 and covered by a sliding plate 82. The plate 82 slides longitudinally with respect to the specimen tunnel in channels 83 provided on access door 16 and has as part of it an aperture similar to the door aperture 81 which is covered by a viewing window 84 of lead glass or other suitable transparent material which is transparent to light but impervious to the radiation used, and an electronic image intensifier 85. The electronic image intensifier 85 can be any of several types, presently on the market, such as those manufactured by Westinghouse Electric Company, General Electric Company, Philips Electronics Corp, Bendix, and others.

The sliding plate 82 may be moved by the operator to position either the window 84 or the image intensifier 85 over the aperture 81. Photographic equipment may also be positioned on plate 82 and slid over the aperture 81 to record the image of the specimen photographically.

To perform the inspection of a part or assembly, the apparatus operates as follows: the specimen is inserted into the specimen tunnel 11 of the housing 10 through the specimen portal 19 and securely mounted on the specimen support 24 by means of the fixture 56 and clamps57. All of the doors allowing access to the interior of the housing are interlocked with the X-ray tube source of power, so that power may not be applied when they are open. This prevents any injury to operating personnel by harmful radiation through their inadvertence.

When all of the access doors have been closed, including the specimen portal 19, the operator actuates the X-ray tube 64 by means of the control panel 72 at the operators station 17.

The sliding plate 82 is then regulated by the operator so that the beam may be viewed either by the fluorescent screen 75 and window 84 or by the image intensifier 85. The screen 75, of course, fluoresces when activated by the beam of radiation.

The specimen support 24 is then actuated to move the specimen into intersection with the X-ray beam. By controlling the movement of the vertical and

horizontal carriages

25 and 26 through the control panel 55, the specimen is moved about in front of the beam until its entire area has been scanned and inspected by the operator.

If better resolution of the image on fluorescent screen 75 is desired, the X-ray tube 64 can be backed away from the specimen by activating'the drive motor 70 from the control panel 73, and driving the bracket 83 rearward on the support frame arms 61 so that the individual rays of the beam will be more nearly parallel when they strike the specimen. It will be understood, of course, that the length of the radiation tunnel 12 and the support frame 60 may be as long as necessary to give sufiicient spacing for the resolution desired in a particular application. Thus, this apparatus, in utilizing a horizontally directed radiation beam, has a significant advantage over apparatus having a vertically directed beam, since, with a horizontally directed beam, the operators position is not aiiected by an increased spacing between the specimen and the X-ray source, no matter how great this increase is. The only modification necessary is the elongation of radiation tunnel 12 and support frame 60.

As a further means of improving the image, the spam is again positioned adjacent the specimen portal.

ing between the specimen and the screen 75 may be adjusted by regulation of the control lever 79 on the access door 16. If positioned closer to the specimen, the screen image will be brighter, the resolution better, and the magnification of the image less. If positioned further away, the magnification of the image will be increased, but the intensity will be less and the resolution poorer.

The intensity of the image will be affected, of course, by the spacing between the X-ray tube and the screen, greater spacing giving less intensity. Generally, therefore, for detailed analysis of a portion of the specimen, the screen will be moved as close as possible to the specimen and the X-ray tube spaced as far away as possible, to the point where the intensity is still sufiicient to give a good image. The positioning of the source of radiation is, of necessity, a compromise, since the best resolution will result when the source is positioned as close as possible to infinity, but if the source is positioned too far from the screen, the intensity of the beam striking the screen is not sufficient to make the image visible. Use of the electronic image intensifier can be of considerable advantage here, since it may be used to detect images having far less intensity than would be needed if viewed with the naked eye.

For general scanning, where resolution is not so important, the screen may be positioned farther away from the specimen to give a slightly magnified presentation and the X-ray source brought closer to the specimen to increase the intensity.

If it is desirable to view the specimen with the radiation beam striking it at a different angle of incidence, operation of the control reel 68 will raise or lower the distal end of the frame 60 through cable 66, and thus tilt the X-ray tube 64 and vary the angle of incidence. Since flaws and defects often show up much more plainly at one angle of incidence than at another, this tilting feature makes analysis much more comprehensive.

After the specimen has been moved about by specimen support 24 and completely scanned by the beam, it Power to the X-ray tube 64 is then shut off and the inspected specimen is replaced by a new one for repetition of the above-described operation. Though the specimens are placed on the specimen support 24 individually in this embodiment, it will be appreciated that by minor changes in the structure, the specimen support could be arranged to carry specimens into and out of the apparatus on an assembly-line basis.

From the above description of the construction and operation of a preferred embodiment of the invention, it will be apparent that this apparatus provides significant advantages not heretofore available. The horizontally disposed radiation beam and T-shaped housing form a construction which allows substantial variations to be made in the spacing between the X-ray source and the specimen, to improve image resolution, without necessitating any major changes in the equipment or inconvenient respositioning of the operator.

Also, large parts and assemblies may be inspected by the apparatus without the use of excessive floor space and with adequate protection for the operator. In fact, because of the power-operated specimen support and the X-ray tube and screen mounting arrangements, the operator may control the apparatus and perform a very complete and comprehensive inspection without ever leaving his convenient operating station 17 in front of the specimen tunnel 11.

With this apparatus, the operator, without leaving the operating station, may move the specimen to any desired position before the beam; vary the spacing between X-ray source and the specimen, and between the screen and the specimen to give the desired combination of magnification, intensity and resolution; and tilt the X-ray source to give the desired angle of incidence. Furthermore, the operator may view the image, either directly 8 by the screen and window 83 or in an intensified version through the image intensifier 85, and, if desired, may make a photographic record of the image.

All of these features have been incorporated by this invention into a compact, self-contained apparatus which is especially adapted to industrial use because of its safety, economy and durability.

While the preferred embodiment of my invention shown in the drawings and described in this specification is fully capable of performing the objects and advantages herein stated, it should be understood that I do not mean to limit myself to the details herein specified, except as defined in the appended claims.

I claim:

1. Fluoroscopic inspection apparatus comprising: a housing having walls of material substantially impenetrable by radiation, said housing having a sliding panel in one wall thereof, said panel having a transparent portion, a radiation source within said housing for emitting a generally horizontal beam of penetrating radiation toward said one wall; support means positioned adjacent said radiation source and in general alignment with said beam for positioning a specimen in said beam, said support means having carriages capable of moving said specimen both vertically and horizontally, simultaneously, in a plane substantially perpendicular to and intersecting said beam; image-producing means for producing an image when activated by said beam, said image-producing means being positioned to intercept said beam after passing through said specimen; an image intensifier device mouned on said sliding panel, whereby said panel can be selectively positioned to align said transparent portion or said image intensifier with the specimen; and support means for said source operable from the exterior of said housing to vary the spacing between said source and the specimen, and for tilting the source to vary the angle of incidence of the beam with respect to the specimen.

2. Fluoroscopic inspection apparatus comprising: a radiation source for emitting a beam of penetrating radiation; support means positioned adjacent said radiation source and in general alignment with said beam for positioning a specimen in said beam; means coacting with said support means for moving said specimen in a plane substantially perpendicular to and intersecting said beam to scan said specimen; image-producing means for pro ducing an image when acitvated by said beam, said image-producing means being positioned to intercept said beam after passing through said specimen; a housing of material substantially impenetrable by said radiation and enclosing said radiation source and support means to shield personnel from said radiation; movable mounting means for supporting said radiation source and said housing for movement toward and away from said support means to vary the spacing between said radiation source and said specimen; and means supporting said mounting means for tiltable movement of said source to change the angle of incidence of said beam on said specimen.

3. Fluoroscopic apparatus comprising: a radiation source for emitting a beam of penetrating radiation; support means positioned adjacent said radiation source and generally aligned with said beam for supporting the specimen in said beam; carriage means on said support means for moving said specimen in a plane substantially perpendicular to and intersecting said beam to scan said specimen; image-producing means for producing an image when activated by said beam, said image-producing means being positioned to intercept said beam after passing through said specimen; a housing of material substantially impenetrable by said radiation and enclosing said radiation source, support means and image-producing means to shield personnel from said radiation; first mounting means for mounting said image-producing means in said housing, said first mounting means being pivotally movable with respect to said housing for varying spacing between said support means and said image-producing means; second mounting means for movably supporting said radiation source in said housing for movement toward and away from said support means to vary the spacing between said radiation source and said specimen; and means supporting said mounting means for tiltable movement of said source to change the angle of incidence of said beam on said specimen.

4. Fluoroscopic inspection apparatus comprising: a radiation source for emitting a generally horizontal beam of penetrating radiation; support means positioned adjacent said radiation source and in general alignment with said beam for positioning a specimen in said beam, said support means having carriages capable of moving said specimen both vertically and horizontally, simultaneously, in a plane substantially perpendicular to and intersecting said beam; image-producing means for producing an image when activated by said beam, said image-producing means being positioned in said beam after said specimen; shielding means for protecting personnel from said radiation; power-operated drive means for driving said support means, said drive means being operable from a remote station; an elongated support frame mounted adjacent said support means for supporting said radiation source; a holder carrying said radiation source with said beam directly toward said support means, said holder being mounted on said support frame for longitudinal movement thereon to carry said source toward and away from said support means; power-operated drive means for moving said holder on said support frame, said drive means being operable from a remote station; and a support arm on the opposite side of said support means from said support frame and supporting said image-producing means in said beam as aforesaid.

References Cited in the file of this patent UNITED STATES PATENTS 2,683,812 Schneeman July 13, 1954 2,767,322 Daly Oct. 16, 1956 20 2,813,201 Wiebe Nov. 12, 1957