US3328775A - Apparatus for reproducing information from photon-emissive storage mediums - Google Patents

Description

June 27, 1967 R w DUWE 3,328,775

APPARATUS FOR REROD UO NG INFORMATION FROM PHOTON-EMISSIVE STORAGE MEDIUMS Filed March 18, 1964 2 Sheets-Sheet 1 I NVENTOR. P055197 144 fll/WE Y June 27, 1967 Filed March 18, 1964 R. W. DUWE APPARATUS FOR REPRODUCING INFORMATION FROM PHOTON-EMISSIVE STORAGE MEDIUMS 2 Sheets-Sheet 2 INVENTOR.

Ra's/597 Mam/E BY j 1 147 f ORA E Y5 United States Patent 3,328,775 APPARATUS FOR REPRODUCING INFORMATION FROM PHOTON-EMISSIVE STORAGE MEDIUMS Robert W. Duwe, Minneapolis, Minn, assignor to Minnesota Mining and Manufacturing Company, St. Paul,

Minn, a corporation of Delaware Filed Mar. 18, 1964, Ser. No. 352,370 4 Claims. (Cl. 340-173) This invention relates to a new and very useful apparatus for readout of information from photon-emissive, electron beam-sensitive recording media.

In one aspect, this invention relates to apparatus for serial readout of a recording medium having a differentially photon-emissive, electron beam-sensitive surface, the differential photon emission from such surface being representative of prerecorded input information.

While those sldlled in the art have long understood that excited electrons cause photon emission from certain types of fluorescent materials, so far as is known to me no one has heretofore provided means for collecting a maximum amount of light emitted by a differentially fluorescent surface when struck by an electron beam of essentially constant intensity. By the present invention, a photon reflector positioned over a differentially photon emitting electron excited surface enables one to collect and reflect photon emission towards an appropriate photoelectric detection means so as to achieve superior readout of prerecorded information.

It is accordingly an object of the present invention to provide apparatus whereby a maximum amount of light emitted by a photon-emissive, electron beam-sensitive surface can be collected and used for readout of information.

Another object of this invention is to provide apparatus for serial readout of stored information from an electron beam-sensitive, photon emissive, sheet-like storage medium whereby such a medium is excitable by electrons to emit photons and such photon emission is collectable to a maximum possible extent and reflected (directed) towards photon sensitive detection means capable of continuously sensing the reflected photon emission.

A further object of this invention is to provide a combination of an electron beam producing means, a photon reflective means, and a photon sensitive detection means whereby serial readout of information from a differentially photon-emissive, electron beam-sensitive recording medium can be accomplished.

Other and further objects of this invention will become apparent to those skilled in the art from a reading of the attached specification, taken together with drawings, wherein:

FIGURE 1 is a diagrammatic sectional view of one embodiment of apparatus of this invention;

FIGURE 2 is an enlarged detailed sectional view of the region beyond the beam focusing coil rotated with respect to FIGURE 1;

FIGURE 3 is a front view of the photon reflector used in the embodiment of FIGURE 1 taken along the line 33 of FIGURE 2;

FIGURE 4 is a view similar to FIGURE 2 but showing an alternative embodiment for an apparatus of this invention;

FIGURE 5 is a view similar to FIGURE 2, but showing another alternative embodiment for apparatus of this invention;

FIGURE 6 is a view similar to FIGURE 2, but showing a further alternative embodiment;

FIGURE 7 is a partially diagrammatic view illustrating a vertical, sectional view of an alternative photon reflector construction usable in the apparatus of this invention;

FIGURE 8 is front view of the photon reflector construction of FIGURE 7 taken along the line 8-8 of FIGURE 7;

FIGURE 9 illustrates a vertical, sectional view of a further alternative construction for a photon reflector usable in the apparatus of this invention; and

FIGURE 10 is a front view of the reflector construction of FIGURE 9.

Background technology Because those skilled in the art may not be familiar with the technology involved, a brief description of the prior art for purposes of this invention is now given:

A storage medium useful in the apparatus of this invention is sheet-like and initially has both:

(a) The capacity to alter selectively, chemically and internally its initial composition adjacent a surface thereof in response to exposure of that surface to differential irradiation, so that, either directly or as a result of subquent processing (i.e. chemical and/or physical treatment) of such medium, such medium thereafter differentially radiates (i.e., transmits, absorbs, and/or emits) photon energy in a manner representative of the initial pattern of differential irradiation, and

(b) The capacity to emitphotons uniformly from a surface thereof in response to uniform electron excitation of a surface thereof.

A species example of a recording medium is as follows:

A two mil wet coating of the following homogeneous formulation is coated onto a 0.75 mil aluminum foil substrate and then dried:

2.0 gram zinc oxide (fluorescent material) 2.0 gram copolymer of 87 mol per-cent vinyl chloride and 13 mol percent vinyl acetate, 8.0 grams acetone (opacifiable material) Using the resulting recording medium, recording is effected thereon in each of the following ways:

(a) A sample is scanned in a raster pattern under high vacuum with an intensity modulated electron beam of 20 kilovolts, 5 microampere peak target current in a 0.5 1O inch beam spot which scans out a 0.5 x 0.5 inch raster for times ranging from to 3 seconds.

(b) A sample is flooded with a non-scanning beam through an image-wise mask of total dimensions 0.5 x 0.5 inch with a 20 kilovolt, 5 microarnpere unmodulted electron beam for times ranging from to 3 seconds.

(c) A sample is exposed for 5 seconds to ultraviolet light by placing it 10 inches from an ultraviolet lamp, having the trade designation B-H6 as sold by the General Electric Company. Thereafter, each sample is heated to C. until a black color is formed selectively in the irradiated area. i

In each case the recorded information is retrievable by placing such sample in a vacuum chamber and scanning same with a focused beam of electrons to provide an image-wise differential photon emission from the sample surface. The photon emission is caused by fluorescence of the zinc oxide in the unexposed areas (the exposed areas being effectively masked). Simultaneously variations in the intensity of photon emission are detected with a photomultiplier. Owing to the fact that the photon emission from each sample in the foregoing illustration is emitted within a solid angle equal to the angle defined (i.e. subtended) by the media surface at the beam impact while the total angle occupied by the photon multiplier is but a small fraction of such solid angle, the photon emission collection efficiency of the photomultiplier is very inefficient. In the case where the recording medium being read out is planar with respect to the readout beam, the photon emission takes place within a solid angle apoaching 27r steradians. If the recording medium is conxly curved towards the readout beam, the photon emis- 311 is emitted over a solid angle greater than about 271' :radians. If the recording medium is concavely curved ith respect to the readout beam, then the photon emission kes place of a total solid angle less than about 271' eradians. It is by the apparatus of the present invention at one achieves a very useful and very eflicient retieval information stored in such a medium.

In storing information by such process, it is necessary modulate the particular form of radiation to be used r storing so as to have the capacity to differentially or lectively irradiate a surface of a storage medium. Modation can be effected by any conventional means whereby tme characteristic of radiation to be used for storage of formation is varied in such a manner or to such a degree .at the resulting diiferential radiation is capable of proicing photon-masking in the storage medium.

During a storing or recording operation, the irradiating ith a differential radiation pattern of a surface of a orage medium results in chemically and internally selecvely altering the initial composition of such medium adcent at least one surface thereof. Such alteration results 1 the creation of a masking layer which is capable of fferentially controlling the passage of photon energy lerethrough in a manner representative of the initial pat- :rn of differential irradiation.

The masking layer, which, while within a storage meium is adjacent one surface thereof, is in the nature of 1 image-wise recording of the input information with him the diiferential radiation is modulated. The input iformation recorded in the masking layer can be con- .dered to comprise or to be in the form of a plurality of iscrete resolution elements, each resolution element being onsidered to be the smallest piece or bit of information resent. In amplitude each such bit is the smallest detectale signal level in a specified area of a recording medium, mi in size it is the wave length of the highest spacial freuency within a specified area of a recording medium.

In general, retrieval is accomplished using uniform elecron excitation of the previously irradiated storage meium. Thus, after storage and development (if necessary r desirable), a storage medium is placed in a vacuum hamber and one surface thereof is exposed to a field of xcited electrons (e.g. an electron beam such as one genrated by an electron gun).

When the resulting medium with its stored information i subsequently scanned with an unmodulated electron eam, the fluorescent material is excited sufliciently to mit photon energy material. As this photon energy passes hrough the photon masking layer, there results a differnce in photon energy emission along the scan route beween the differentially photon masked and unmasked reas. This difference in photon energy emission is detected hotoelectronically. Photon energy detectors are well ;nown and include such devices as photocells, photomul ipliers, and the like.

Naturally, as in any storage and retrieval system in- 'olving a scanning operation, the resolution efficiency of etrieval when practicing the processes of this invention lepends upon the relationship between unmodulated scanring beam size and the respective resolution elements comirising the stored input information in the masking layer )f the recording medium. In order not to lose or fail to etrieve recorded information on readout, the relationship )etween the unmdoulated scanning electron beam and each 'esolution element within a specified area of a storage nedium surface should be such that the electron beam width measured in terms of the direction of relative veocity between the storage medium and the beam is not greater than the width of individual resolution elements be read out (retrieved) measured in the same direction.

While the scanning electron beam used to excite the iuorescent material during retrieval is referred to as being unmodulated, those skilled in the art will appreciate that during the tracing of a raster by the beam in a scan field some sort of blanking may be employed during beam return for a new scan path in a raster pattern, for example one involving horizontal and vertical deflection, so that in this sense the beam is truly unmodulated only during its passage across a scan field. Furthermore, in certain situations, it may be desirable to impose upon the unmodulated portion of such beam pulsed signal information or the like, for example to cause particular effects upon, in, or about the recording or storage medium during readout. However, for retrieval purposes differential photon emission from the masking surface of the storage medium is achieved by an electron beam which is essentially uniform during residence time upon a storage medium. It will be appreciated that, as a consequence, the differential fluorescent pattern produced from the surface of such storage medium as a result of such uniform beam impact produces photon emission bearing information which need not be at all associated with or carried by the unmodulated scanning readout beam itself.

Apparatus description Referring to the drawings, it will be seen that in the embodiment shown in FIGURES 1-3, the entire apparatus is enclosed in an envelope 9 which is adapted for evacuation and defines therewithin a generally elongated, generally cylindrically shaped cavity. As those skilled in the art will appreciate, and as will become more apparent from the subsequent description herein, this envelope need only enclose the portion of the apparatus which is to be traversed by the electron beam.

In FIGURE 1 there is seen an electron source, herein designated in its eentirety by the numeral 10, Source 10 is adapted to emit along axis 11 within envelope 9 a beam of electrons 12 depicted in outline form. The electron source 10 is seen to comprise a filament or cathode 13, a grid 14 and an anode 15. The construction of electron sources is well known to those of ordinary skill in the art.

An electron beam optical system herein designated in its entirety by the muneral 17 is positioned generally in the middle portion of envelope 9. This system 17 is adapted to focus the beam 12. In the embodiment shown, the system employs one electromagnetic lens 18 which is axially aligned with the axis of beam 12 and one plate 19. Plate 19 has generally circular, centrally located aperture 21 therein which serves to limit and collimate beam 12.

The construction of electron optical systems or means is likewise well known to those of ordinary skill in the art. It will be appreciated that electrostatic as well as electromagnetic lenses can be used. One can employ more than one lens and a plurality of aperture plates for focusing and collirnating an electron beam. Depending upon the cross-sectional size, shape, intensity, etc, of the beam needed, as well as the type of electron source used and the type of recording medium involved, those skilled in the art will appreciate that it is convenient to use any suitable combination of electron source and electron optical system.

Positioned in envelope 9, in axial alignment with beam 12 after or following that portion of the electron optical means or source 17 which is furthest removed from the electron source 10, a beam deflection means is provided. As shown in FIGURES 1 and 2, such beam deflection means is provided by an electromagnetic deflection yoke 20, which is positioned adjacent the lens 18. The yoke 20 is of conventional construction and, like any beam deflection means, is adapted to cause the beam 12 to move over predetermined portions of a scan field upon the face of platform 24in a raster pattern (not shown). Platform 24 is located within the envelope 9 in proximity to the end thereof opposite that in which the electron source 10 is positioned. Lens 18 is chosen so as to have a suitably long focal length in order to maintain a considerable distance between lens 18 and platform 24 and thereby accommodate yoke 20 and reflector 27.

It will be appreciated that embodiments can be constructed which do not employ beam deflection means. In these instances a relative velocity between the electron beam and the recorded information (i.e., the recording medium) can be provided by continuously moving the recorded information past (i.e., through) a stationary electron beam by some sort of conventional transport mechanism (not illustrated).

In order to position a prerecorded differentially photonemissive, electron beam-sensitive recording medium 23 within the scan field upon the face of platform 24, some sort of positioning and/or supporting means is provided. As shown in FIGURES 1 and 2 such means comprises the platform 24 over which is passed discontinuously, or continuously, a photon-emissive, electron beam sensitive recording medium 23 which in this case is in tape or strip form. Movement of the medium 23 across platform 24 in front of beam 12 is provided by a conventional tape transport mechanism, herein designated in its entirety by the numeral 26. In some embodiments, the supporting means 24 and the mechanism 26 can be combined. While in the embodiment shown, the tape transport mechanism 26, the platform 24, and the medium 23, are positioned within the envelope 9, those skilled in the art will appreciate that alternative and equivalent arrangements can be conveniently used.

Positioned in envelope 9 between the yoke 20 and the platform 24 isa photon reflective means, here a circular reflector 27. This reflector 27 includes a spherically concave reflective surface 28 adapted to collect photon emission within a large solid angle approaching a maximum of about 21r steradians measured with respect to the surface of a flat medium 23 and the impinging beam 12. Naturally, if the surface of the medium is not flat, the available solid angle (the angle subtended by the medium) can be greater than 21r and the reflective surface can be designed to collect over a greater solidangle than 211-. This reflector 27 can be constructed of any conventional material, such as aluminum, silver, or the like, which is relatively stable and non-volatile under the vacuum conditions conventionally associated with electron beam operation. I found that aluminum is a particularly useful material for constructing reflectors 27; I polish its reflective surface to such a degree that it becomes an effective reflector of photon energy. In general, I prefer to use concave reflective surfaces 28 which are ellipticallyshaped, because the known optical properties associated with reflectors of such shape make it easier and preferable to concentrate and reflect from surface 28 towards a focal plane the photon emission received from a medium 23.

In order to permit the beam 12 to pass unimpeded to the scan field 22 through the reflector 27, reflector 27 is provided with a small aperture 32 whose location and dimensions are so chosen as to permit the beam to move over the entire scan field in a raster pattern without striking the reflector 27. In FIGURES 1 and 2, the

reflector 27 and aperture 32 are constructed so that the axis 11 of beam 12 passes through the apex region of reflector 27. In general, the reflector 27 is positioned in envelope 9 after the electron optical system 17 (and yoke 20, if used) and before the supporting means 24. Those skilled in the art will appreciate that a number of different possible constructions can be used for the reflective means in place of the reflector 27; a few alternative constructions are hereinafter described. Also, such people will appreciate that the axis of reflector 27 can be angularly disposed with respect to the axis 11 of beam 12 as when it is desired to position the photoelectric device to one side of the medium 23. In general however, a reflective means is so positioned as not to impede or affect the path of the beam. Thus, the

reflective means is always so positioned or constructed as to be discontinuous at the path of the beam. In the embodiment of FIGURES 1 and 2, the aperture 32 provides .the discontinuity in reflector 27. Naturally, it is preferred to keep the aperture 32 as small in its dimensions as conveniently possible in order to maximize the amount of photon emission which can be collected by the surface 28 of reflector 27, and reflected to the photon detector means (i.e., a photomultiplier 29). Similarly, which it is preferred to use reflective means capable of reflecting photon energy to a focal plane or point, it will be appreciated that for many purposes the focal plane can be poorly defined, if at all.

Positioned generally after the medium 23 with respect to the electron source 10 is a photon-detection means. Any conventional photon electric detection means can be used in the embodiments shown, including devices such as photocells, photo-multipliers, and the like. For example, as shown in FIGURES 1 and 2, such a means is a photo-multiplier 29 which converts photon energy input into an electrical signal output representative of the photon energy input. The photo-multiplier 29 is positioned in envelope 9 with respect to the reflector 27 and the medium 23 so as to be in a position to collect as much as possible (ideally all) of the photon rays 31, reflected from the surface 28 of reflector 27. The photomultiplier 29, as a practical matter, can be positioned exactly at the image or focal plane (if one is definable) of the photon rays 31 or it can be positioned before or after such focal plane.

While the photon detection means as shown in the embodiments herein is positioned inside envelope 9, those skilled in the art will appreciate that in other embodiments such means can be positioned outside of such an envelope 9. Thus, a window or lens (not shown) can be positioned in the end of envelope 9. Then, the photomultiplier 29 can be suitably positioned in front of such window outside envelope 9 and there used to sense the photon emission from medium 23 as reflected from reflector 27 at some point outside of the envelope 9. In general, the photon detection means is positioned after the supporting means with respect to the direction of. beam movement and adapted continuously to sense photon energy reflected from the reflective means.

Those skilled in the artwill appreciate that, while in the embodiments shown in the drawings the medium 23 is positioned generally normally to beam 12, there is nothing particularly critical in such an arrangement and indeed it is possible to position the medium 23 at an angle with respect to the beam 12. Similarly, it may be desirable to position'the reflector 27 at such angle as to reflect photon emission from medium 23 towards photon detection means not axially aligned with beam axis 11. The exact angular interrelationship between medium 23 (or platform 24), reflector 27, beam 12 (or source 10), and photon detection means (like photo-multiplier 29) can obviously vary widely from one embodiment to another, as will readily be appreciated by those of ordinary skill in the art.

Concerning the relationship between the reflector 27 and the photo-multiplier 29 in FIGURES 1 and 2, it will be appreciated that, while it is generally convenient and even desirable to keep the photo-multiplier 29 behind and spaced at a short distance from the back of the medium 23, it is quite possible and convenient in some circumstances, depending upon the particular apparatus involved, the shape of the reflector surface 28, the type of photon sensitive detection means employed, the type of medium 23 employed, and other factors, to position the photo-multiplier 29 at a level or position such that the photo-multiplier 29 is approximately equivalent to or in lateral alignment with the surface of the recording medium 23. The photomultiplier 29 is not positioned before or in front of the medium 23 because in such an arrangement the photo-multiplier 29 would interfere with the oton emission from the medium 23 and to this extent t down upon the light collection efliciency of any arngement involving reflector 27, medium 23, and photolltiplier 29. I

It will be appreciated that the apparatus of this inven- In is particularly useful when one is reading out inrmation stored in photon-emissive, electron beam-sensie media which are substantially opaque to the emitted totons since the radiation from such media generally nstitutes a point source, in radiation distribution caus only the Zrr steradians on the electron beam struck to to be available for the detection solid angle when the edia is flat at the position of beam impact. Indeed, in der to assure that no transmission of electron energy photon energy through a medium will occur, it is deable in many instances to position an opaque platform l back of the medium 23 as has been done in the em- )diment shown in FIGURES 1-3 so as to assure no lse readouts or collections of photon emission.

In the embodiment shown in FIGURES 1-3, together e yoke 20 and the transport mechanism 26 comprise eans for relatively moving beam 12 over predetermined )rtions of the differentially photon-emissive surface of edium 23. While the embodiment employs a medium 23 tape form, it will be appreciated that the apparatus of is invention can also be used with media in sheet form.

'hen using sheet-like media, an appropriate conventional ieet or card advancement mechanism (not shown) can employed in place of transport mechanism 26. Of xurse, one can manually place a medium 23 on plattrm 24 and not use either a tape transport mechanism a card advancement mechanism. However, apparatus 1' this invention requires some means for relatively movg beam 12 over medium 23, so that if no such mecha- .sm is employed then it is usually convenient to employ yoke 20 or equivalent beam deflection means.

Also in the embodiment shown in FIGURES l-3, to- :ther the source 10 and the electron optical system 17 )rnprise electron beam producing means. Such means eeds to be capable of producing an electron beam 12 aving a width measured in the direction of relative alocity between beam 12 and medium 23 which is not :eater than the width of individual resolution elements not shown) associated with said medium 23 measured 1 the same direction.

Photomultiplier 29 is positioned to receive photon enrgy reflected from reflector means 27. The photomultilier 29 is adapted to continuously sense the differential nd photon energy emitted by the medium 23 to produce it electric signal output generally corresponding to the rerecorded input information on medium 23. The photomlti-plier 29 senses photon energy reflected from reflec- )I' 27 at a rate not less than that at which differences in hoton emission from the beam-struck surface of medium 3 occur during relative movement of beam 12 to medim 23. Such differences in photon emission correspond individual resolution elements in the recorded informaion, as indicated above.

Alternative embodiments In FIGURES 410 are shown alternative embodiments |f apparatus of this invention or portions thereof. Unless lth6I'WlS6 indicated, the elements in each of these respecive figures are numbered the same as those in FIGURES .-3 except that prime marks are added thereto for disinguishing purposes.

In FIGURE 4, there is seen an alternative embodiment vherein the deflection yoke and the reflector are one com- )osite structure herein designated in its entirety by the iumeral 33. The reflector-yoke structure 33 has a con- :ave reflective surface 34 formed in its end portion remote from the source (not shown). Structure 33 is advantage- )usly compact.

FIGURE discloses a portion of another alternative embodiment wherein a photocell 36 is positioned outside 1 vacuum enclosure 37. An electron beam 38 is shown passing through a magnetic deflection yoke 39 and impinging on a prerecorded medium 41. The consequent photon emission, shown as rays 42, is reflected by a reflector 43 (constructed similarly to reflector 27-) through a photon transmissive window 44 of glass or the like to photocell 36. Window 44 is mounted across an aperture 4-6 in enclosure 37 by means of a conventional O-ring seal 47 and threaded cap 48 which together seal the photon transmissive window 44 to enclosure 37. The entire conventional transport mechanism 49 is shown housed within enclosure 37.

In FIGURE 6 is shown a' further alternative embodi ment wherein an electron beam 51 strikes a prerecorded medium 52 and produces photon emission as rays 53. Rays 53 leave medium 52 and strike, respectively, reflectors 54 and 56 at various angles, from which they are reflected onto respectively, photomultipliers 57 and 58. The entire assembly is housed within an enclosure 59'. Medium 52 is opaque and stationary during scanning by beam 51, which is deflected in a horizontal pattern by yoke 61. This configuration of apparatus elements provides two individual detectable images and greater reliability of signal detection for high resolution readout of high density information storage, for example. When image production from recorded information is desired, this arrangement is sometimes less desirable than others described herein because of photon aberration and image astigmatism. If more than two separate detectable images are desired, additional reflectors may be incorporated into the arrangement, space and configuration, parameters permitting.

In FIGURES 7 and 8 (FIGURE 8 is reduced 25% due to space limitations) is illustrated an alternative reflector construction and diagrammatically a manner of using same. Here, an electron beam 62 after passing through an aperture of reflector 68 impinges upon a prerecorded medium 63 generating rays 64, 65, and 66, among others (not shown). These rays 64, 65, and 66 strike the reflective surface 67 of reflector 68. Owing to the shape of surface 67 (shown generally in FIGURE 7 as a diametrical, vertical section), rays 64 and 66 which em-it from medium 63 in respective directions closely parallel to but in an opposite direction from, beam 62, strike surface 67 and are directed laterally, radially and outwardly from the reflector axis (which in FIGURE 7 is coincident with beam axis 62). After next striking surface 67, the rays 64 and 66 are reflected outwardly to photomultiplier 69 in the direction of beam 62 movement. Ray which leaves medium 63 at an acute angle is reflected diametrically across surface 67 after impact thereagainst, to be finally reflected outwardly to photomultiplier 69. The surface 67 of reflector 68 is so shaped as not only to have the usual properties of an elliptical reflector but also to have the capacity to collect rays emitted substantially along or towards the axis of beam 62, which rays would other wise represent lost energ since they would otherwise reflect back towards medium 63 after reflection from mirror having a conventional elliptically reflective surface. Naturally, the shape of the surface 67 of reflector 68 must be carefully formed for optimum results.

In FIGURES 9 and 10 is shown one additional reflector construction suitable for use in apparatus of this invention. Here the reflector comprises a pair of spherical segments 70 and 71, respectively, each positioned with respect to one another and to the axis 72 of a beam 73 approximately as suggested in FIGURES 9 and 10. FIG-' URE 9 can be considered to be a vertical, sectional View taken along the line 9-9 of FIGURE 10.

In all embodiments, the photoelectric detection means is so positioned as to have reflected photon energy strike its photo-sensitive portions.

Having described my invention, I claim:

1. Apparatus for serial readout of a recording medium having a differentially photon-emissive, electron beamsensitive surface, the differential photon emission from such surface being representative of prerecorded input information, said apparatus comprising:

(a) a supporting envelope adapted for evacuation defining therewithin a generally elongated cavity,

(b) electron beam producing means positioned in said envelope and adapted to emit generally lengthwise within said envelope at substantially uniform electron beam,

(c) means for supporting a differentially photon-emissive, electron beam-sensitive recording medium in the path of said electron beam, the differentially photon emissive areas associated with a said recording medium being resolvable into a plurality of discrete resolution elements,

(d) means for relatively moving said electron beam over predetermined portions of a said recording medium when a said medium is so supported,

(c) said electron beam having during such relative movement a maximum width measured in the direction of relative velocity between said electron beam and a said recording medium not greater than the Width of individual resolution elements to be read out associated with a said medium measured in the same direction,

(f) photon reflective means positioned in said envelope between said electron beam producing means and said supporting means, said photon reflective means being discontinuous across the path of said beam,

(g) said reflective means including a concave reflective surface adapted both to collect photon energy emitted from the beam-struck surface of such a recording medium Within a solid angle not larger than that solid angle subtended by said recording medium at the impact situs of said beam on such beam-struck surface and to reflect such energy in a direction generally away from said electron source, and

(h) photoelectric detection means positioned to receive photon energy reflected from said reflective means and adapted to continuously sense the differential in said photon energy emitted and produce an electric signal output generally representative of said prerecorded input information on a said medium.

2. Apparatus for serial readout of a recording medium having a differentially photon-emissive, electron beamsensitive surface, the differential photon emission from such surface being representative of prerecorded input information, said apparatus comprising:

(a) a supporting envelope adapted for evacuation defining therewithin a generally elongated, generally cylindrically-shaped cavity,

(b) an electron source positioned in one end of said envelope and adapted to emit generally axially within said envelope a substantially uniform beam of electrons, said source including a filament, a grid, and an anode,

(c) electron optical means positioned generally in the middle portion of said envelope and adapted to focus said beam in a scan field defined across said beam axis within said envelope in proximity to the opposite end thereof,

(d) beam deflection means positioned in said envelope in axial alignment with said beam following that portion of said electron optical means furthest removed from said electron source and adapted to cause said beam to move over predetermined portions of said scan field in a raster pattern,

(e) means for supporting a differentially photon-emissive, electron beam-sensitive recording medium in the path of said electron beam, the differentially photon emissive areas associated with a said recording medium being resolvable into a plurality of discrete resolution elements,

(f) means for relatively moving said electron beam over predetermined portions of a said recording medium when a said medium is so supported,

(g) said electron beam having during such relative movement a maximum width measured in the direction of relative velocity between said electron beam and a said recording medium not greater than the width of individual resolution elements to be read out associated with a said medium measured in the same direction.

(h) photon reflective means positioned in said envelope between said electron beam producing means and said supporting means, said photon reflective means being discontinuous across the path of said beam,

(i) said reflective means including a concave reflective surface adapted both to collect photon energy emitted from the beam-struck surface of such a recording medium within a solid angle approaching that solid angle subtended by said recording medium at the impact situs of said beam on such beam-struck surface and to reflect such energy in a direction generally away from said electron source, and

(j) photoelectric detection means positioned to receive photon energy reflected from said reflective means and adapted to continuously sense the differential in said photon energy emitted and produce an electric signal output generally representative of said prerecorded inut information on a said medium.

3. Apparatus for serial readout of a recording medium having a differentially photon-emissive, electron beamsensitive surface, the diflerential photon emission from such surface being representative of prerecorded input information, said apparatus comprising:

(a) a supporting envelope adapted for evacuation defining therewithin a generally elongated, generally cylindrically-shaped cavity,

(b) an electron source positioned in one end of said envelope and adapted to emit generally axially within said envelope at substantially uniform beam of electrons, said source including a filament, a grid, and an anode,

(c) electron optical means positioned generally in the middle portion of said envelope and adapted to focus said beam in a scan field defined across said beam axis within said envelope in proximity to the opposite end thereof,

(d) beam deflection means positioned in said envelope in axial alignment with said beam following that portion of said electron optical means furthest removed from said electron source and adapted to cause said beam to move over predetermined portions of said scan field in a raster pattern,

(e) means for supporting a differentially photon-emissive, electron beam-sensitive recording medium in said envelope in the path of said electron beam, the differentially photon emissive areas associated with a said recording medium being resolvable into a plurality of discrete resolution elements,

(f) means for relatively moving said electron beam over predetermined portions of a said recording medium when a said medium is so supported,

(g) said electron beam having during such relative movement a maximum width measured in the direction of relative velocity between said electron beam and a said recording medium not greater than the width of individual resolution elements to be read out associated with a said medium measured in the same direction.

(h) said envelope having defined in its opposite end portion a photon transmissive window,

'(i) photon reflective means positioned in said envelope between said electron beam producing means and said supporting means, said photon reflective means being discontinuous across the path of said beam, (j) said reflective means including a concave reflective surface adapted both to collect photon energy emitted from the beam-struck surface of such a recording 1 1 2 medium within a solid angle approaching a 211- steradians over the impact situs of said beam on such beam-struck surface and to reflect such energy in a direction generally away from said electron source,

(b) means for collecting photon energy emitted from the so beam-struck surface of said medium Within a and 5 solid angle not larger than that solid angle subtended (k) photoelectric detection means positioned outside by said medium at the impact situs of said beam on of said envelope adjacent said window so as to resuch beam-struck surface and for reflecting such ceive photon energy reflected from said reflective energy in a direction generally away from said elecmeans and adapted to continuously sense the differtron source, and

ential in said photon energy emitted and produce an (c) means for sensing photon energy from said means electric signal output generally representative of said prerecorded input information on a said medium.

for collecting and reflecting and for converting such energy into a corresponding electric signal output,

thereby to electronically retrieve prerecorded information from said medium.

4. Apparatus for electronically retrieving prerecorded formation from a recording medium having a difieren- ,lly photon-emissive, electron beam responsive surface, e differential photon emission from such surface being presentative of prerecorded input information, said apratus comprising in combination:

References Cited UNITED STATES PATENTS (a) means for generating and for relatively moving 4/1956 Rajchman et 340173 a substantially uniform electron beam over predeter- 2999163 9/1961 Beese 313 92 X mined portions of a said recording medium, said elec- 3099762 7/1963 Hertz 313*275 X tron beam having during such relative movement 3,181,172 4/1965 Boblett thereof a maximum Width measured in the direction of relative velocity between said electron beam and BERNARD KONICK P'lmary Exammer' said medium not greater than the width of individual J. BREIMAYER, Assistant Examiner.

Claims (1)

1. 3. APPARATUS FOR SERIAL READOUT OF A RECORDING MEDIUM HAVING A DIFFERENTIALLY PHOTON-EMISSIVE, ELECTRON BEAMSENSITIVE SURFACE, THE DIFFERENTIAL PHOTON EMISSION FROM SUCH SURFACE BEING REPRESENTATIVE OF PRERECORDED INPUT INFORMATION, SAID APPARATUS COMPRISING: (A) A SUPPORTING ENVELOPE ADAPTED FOR EVACUATION DEFINING THEREWITHIN A GENERALLY ELONGATED, GENERALLY CYLINDRICALLY-SHAPED CAVITY, (B) AN ELECTRON SOURCE POSITIONED IN ONE END OF SAID ENVELOPE AND ADAPTED TO EMIT GENERALLY AXIALLY WITHIN SAID ENVELOPE A SUBSTANTIALLY UNIFORM BEAM OF ELECTRONS, SAID SOURCE INCLUDING A FILAMENT, A GRID, AND AN ANODE, (C) ELECTRON OPTICAL MEANS POSITIONED GENERALLY IN THE MIDDLE PORTION OF SAID ENVELOPE AND ADAPTED TO FOCUS SAID BEAM IN A SCAN FIELD DEFINED ACROSS SAID BEAM AXIS WITHIN SAID ENVELOPE IN PROXIMITY TO THE OPPOSITE END THEREOF, (D) BEAM DEFLECTION MEANS POSITIONED IN SAID ENVELOPE IN AXIAL ALIGNMENT WITH SAID BEAM FOLLOWING THAT PORTION OF SAID ELECTRON OPTICAL MEANS FURTHEST REMOVED FROM SAID ELECTRON SOURCE AND ADAPTED TO CAUSE SAID BEAM TO MOVE OVER PREDETERMINED PORTIONS OF SAID SCAN FIELD IN A RASTER PATTERN, (E) MEANS FOR SUPPORTING A DIFFERENTIALLY PHOTON-EMISSIVE, ELECTRON BEAM-SENSITIVE RECORDING MEDIUM IN SAID ENVELOPE IN THE PATH OF SAID ELECTRON BEAM, THE DIFFERENTIALLY PHOTON EMISSIVE AREAS ASSOCIATED WITH A SAID RECORDING MEDIUM BEING RESOLVABLE INTO A PLURALITY OF DISCRETE RESOLUTION ELEMENTS, (F) MEANS FOR RELATIVELY MOVING SAID ELECTRON BEAM OVER PREDETERMINED PORTIONS OF A SAID RECORDING MEDIUM WHEN A SAID MEDIUM IS SO SUPPORTED, (G) SAID ELECTRON BEAM HAVING DURING SUCH RELATIVE MOVEMENT A MAXIUM WIDTH MEASURED IN THE DIRECTION OF RELATIVE VELOCITY BETWEEN SAID ELECTRON BEAM AND A SAID RECORDING MEDIUM NOT GREATER THAN THE WIDTH OF INDIVIDUAL RESOLUTION ELEMENTS TO BE READ OUT ASSOCIATED WITH A SAID MEDIUM MEASURED IN THE SAME DIRECTION. (H) SAID ENVELOPE HAVING DEFINED IN ITS OPPOSITE END PORTION A PHOTON TRANSMISSIVE WINDOW, (I) PHOTON REFLECTIVE MEANS POSITIONED IN SAID ENVELOPE BETWEEN SAID ELECTRON BEAM PRODUCING MEANS AND SAID SUPPORTING MEANS, SAID PHOTON REFLECTIVE MEANS BEING DISCONTINUOUS ACROSS THE PATH OF SAID BEAM, (J) SAID REFLECTIVE MEANS INCLUDING A CONCAVE REFLECTIVE SURFACE ADAPTED BOTH TO COLLECT PHOTON ENERGY EMITTED FROM THE BEAM-STRUCK SURFACE OF SUCH A RECORDING MEDIUM WITHIN A SOLID ANGLE APPROACHING A 2$ STERADIANS OVER THE IMPACT SITUS OF SAID BEAM ON SUCH BEAM-STRUCK SURFACE AND TO REFLECT SUCH ENERGY IN A DIRECTION GENERALLY AWAY FROM SAID ELECTRON SOURCE, AND (K) PHOTOELECTRIC DETECTION MEANS POSITIONED OUTSIDE OF SAID ENVELOPE ADJACENT SAID WINDOW SO AS TO RECEIVE PHOTON ENERGY REFLECTED FROM SAID REFLECTIVE MEANS AND ADAPTED TO CONTINUOUSLY SENSE THE DIFFERENTIAL IN SAID PHOTON ENERGY EMITTED AND PRODUCE AN ELECTRIC SIGNAL OUTPUT GENERALLY REPRESENTATIVE OF SAID PRERECORDED INPUT INFORMATION ON A SAID MEDIUM.

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