scholarly journals The Largest Possible Microscope

1994 ◽  
Vol 2 (5) ◽  
pp. 10-10
Author(s):  
Sterling P. Newberry
Keyword(s):  
High Voltage ◽  
Focal Length ◽  
Big Science ◽  
Distinguishing Characteristic ◽  
Voltage Electron ◽  
Science Projects ◽  
High Voltage Electron ◽  
Ordinary Light ◽  
Electron Microscopes ◽  
Ultra High Voltage

In this day of resistance toward big science projects it may be futile to worry about how to produce the largest possible microscope. But since it doesn't cost anything to day dream, and times may change, it is fun to consider superlative enterprises.One must grant that Ultra High Voltage Electron Microscopes are much larger than we wish they were, and one wonders if there is a contest afoot to see which AEM can have the largest foot print, but a new possibility has arisen which, seriously, could dwarf them all - yet have some possible use.I am referring to the discovery of an example of a gravitation lens for ordinary light. Now the distinguishing characteristic of a microscope from a telescope is that the object eyepiece and the object near the focal length of the lens.

The Reduction of Chromatic Aberrations Due to Instrumental Instabilities

1971 ◽  
Vol 29 ◽  
pp. 14-15
Author(s):  
J. S. Lally ◽  
R. Evans
Keyword(s):  
Electron Microscope ◽  
High Voltage ◽  
Focal Length ◽  
Chromatic Aberration ◽  
Objective Lens ◽  
Usual Practice ◽  
Voltage Electron ◽  
Short Focal Length ◽  
Chromatic Aberrations ◽  
Electron Microscopes

One of the instrumental factors often limiting the resolution of the electron microscope is image defocussing due to changes in accelerating voltage or objective lens current. This factor is particularly important in high voltage electron microscopes both because of the higher voltages and lens currents required but also because of the inherently longer focal lengths, i.e. 6 mm in contrast to 1.5-2.2 mm for modern short focal length objectives.The usual practice in commercial electron microscopes is to design separately stabilized accelerating voltage and lens supplies. In this case chromatic aberration in the image is caused by the random and independent fluctuations of both the high voltage and objective lens current.

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