GB1436615A - Electron mirror apparatus - Google Patents

Abstract

1436615 Cathode ray storage tubes MINNESOTA MINING & MFG CO 17 July 1973 [18 July 1972 (2)] 34009/73 Heading H1D Electron beam mirror apparatus includes gun 11, magnetic prism 10, modulating electron mirror 4 to which the input information can be applied and which can direct the beam back to prism 10, a plurality of storage electron mirrors capable of passive reflection, or impingement to effect storage, and readout device 12. Electron focusing lens 13 increases the beam crosssection to encompass any pattern of charge presented at the modulating mirror. Electron beam shaping and directing means includes the three element focusing lenses 13-16, objective lenses 18, 21 (e.g. three element multi-apertured immersion lens) and deflection units 19, 20, 22 and 23. Procedural details, including erasure and voltages are discussed, for example w.r.y., Figs. 8-10 (not shown). Energy spread may be reduced at one or more mirrors by collection and mirroring of high and low energy electrons respectively. Fig. 11 (not shown) is alternative (linear) apparatus. Storage at more than one mirror allows comparison and improves reliability. Readout device 12 may be a diode matrix allowing individual diode monitoring. Prism 10 may be Helmholtz coils (Fig. 3, not shown) with shaped polepieces 25 (dimensions given). Mirror 4 may include a Vidicon type diode array (e.g. 3À2 x 10<SP>5</SP> sites/cm.<SP>2</SP>), sequential electron and light incidence uniformly charging. The light may be binary information from a plasma or L.E.D. panel. The modulating mirror (Fig. 4, not shown) may include light sources (36), lenses (39), (9), and photodiode array (38), or Fig. 5 (not shown), fine wires or fibres (5) in insulator (7) with high resistivity surface coating between which voltages are applied. Fig. 6 (not shown) is a multi-aperture immersion lens with holed plates 40-42 biased to control beam cross-section, insulator sleeve (45) (e.g. glass) and intervening plate (43) removing stray electrons. Inhibition of distortions by lens 18, 21 are discussed. Each deflection unit includes eight electrostatic graphite areas (46). Storage may be a dielectric film (e.g. bismuth titanate, aluminium oxide, or silicon dioxide) on a conductor (e.g. Si wafer). Varied hole sizes in rings (47-49) on grooved base (51), (Fig. 7, not shown) determine focusing. The outer surface of ring (47) is ground flat to be parallel to mirror 4 surface. Fig. 11 includes two U-shaped permanent or electromagnets (61, 62), storage mirrors (6, 6A, 6B, 8, 8A, 8B) with respective lenses and deflection units. The focusing lenses may be 3 element (Fig. 13, not shown). Reference is made to mirror field gradients due to surface topography, and electrical charge distribution or magnetization. Many dimensions are disclosed and a pointed thermal cathode in a triode electron gun as used in electron microscopes may be used for gun 11.