Eduard Hartung and Sven Engbers
Cathode ray – light sources
Applications● Electron microscopy● Cathode ray tube ● oscilloscope● Electron beam lithography● X – ray tube● ...
History
● 1897: Karl Ferdinand Braun – Inventor of the Braun tube
● 1906: Max Diekmann – First electrical TV (3 x 3 cm, 10 fps)
● 1926: Kenjiro Takayanagi– First black – and – white picture tube in Japan
● 20. century: Professor Manfred von Ardenne – Constant further development
Cathode ray tube - construction● Cathode● Wehnelt cylinder
– Brightness control, contrast optimisation
– Pre focussing● several focussing electrodes● Deflection plates / coils● Anode
– Acceleration
Cathode ray tube – Ray generation
● Heating of the cathode● Electron cloud between cathode and Wehnelt cylinder● Acceleration due to high electric field
– Oscilloscope: 500 – 8000 V– TV: 25 – 35 kV– Material processing / X – ray tubes: >100 kV
● Current <1mA
Cathode ray tube – beam deflection and modulation
● TV's:– Magnetic deflection
(Coils)● Oscilloscopes:
– Electrostatic deflection (Pair of plates)
● Modulator electrode (Wehnelt Zylinder)
– Negative electrical potential compared to cathode
– Modulation in the range of MHz
– Amplitude about 250 V
Cathode ray tube – Color● Three electron guns (red,
green, blue)● aperture grille design
– High brightness● Shadow mask design● Chromaclear design
Scanning electron microscope
● Resolution of ~2nm● High depth of sharpness● Information about
compounding of
Fundamental building
Electron-gun
Thermionic Gun Field-emission gun
Fokusing Lens
Magnetic electron-lens Fokusing with lorenz-force:F=e⋅×B
Reaktion in Material
● Secondary electrons● Back scattered elctrons● x-Ray
Detektion
Everhart-Thornlay detector
Thank you for your attention!
Sources● http://www.uni-tuebingen.de/iap/fprakt/pdf/AnleitungREM.pdf ● http://en.wikipedia.org● Einführung zum Rasterelektronenmikroskop● Skript of Prof. Dr. Lödding