college of nanoscale science & engineering elroy tatem bradley thiel and miguel rodriguez...
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College of Nanoscale Science & Engineering
Elroy Tatem
Bradley Thiel and Miguel Rodriguez
University at Albany Summer Research Program
Electronics of Electron Microscopes
College of Nanoscale Science & Engineering
Introduction
Troubleshoot and repair a malfunctioning scanning electron microscope (SEM)
Troubleshoot and repair a transmission electron microscope (TEM)
College of Nanoscale Science & Engineering
A Vital Research Tool
Characterization tools are necessary in all areas of research at CNSE
Must be made available for students, professors, and other personnel to use
Taken from <http://www.trafficticketpayment.com/images/cartoon_line.big.jpg>
College of Nanoscale Science & Engineering
Why not Use an Optical Microscope?
Much greater resolving power• Resolution is limited by the wavelength of the incident beam
Taken from J.I. Goldstein, Scanning Electron Microscopy and X-Ray Microanalysis,
(Plenum Press,NY,1980)
College of Nanoscale Science & Engineering
Why Not Use an Optical Microscope? (Cont.)
Optical microscopes use light• The wavelength of visible light is a few hundred nanometers• High resolution optical microscopes can use light at a wavelength of
about 20nm
Electron microscopes use electrons• Wavelength of an electron beam can be smaller than a tenth of a
nanometer
College of Nanoscale Science & Engineering
What is an SEM?
College of Nanoscale Science & Engineering
The Breakdown The SEM is a series of systems
that must communicate with each other
• VacuumVacuum
• High voltage supplyHigh voltage supply
• InputsInputs
• Electron opticsElectron optics
• Detector(s)Detector(s)
• Signal processing systemSignal processing system
• DisplayDisplay
College of Nanoscale Science & Engineering
How do they communicate?
College of Nanoscale Science & Engineering
College of Nanoscale Science & Engineering
The Problem With this SEM
The first observation
• No horizontal deflection while in TV mode
• There is vertical deflection
• None of the other visual modes have this problem
College of Nanoscale Science & Engineering
What does this Tell Us?
Problem can be in one of three places• Scan Coil• CRT• Source of scan signal
Start from the source• The best way to start
troubleshooting is to find the source of the signal.
College of Nanoscale Science & Engineering
Troubleshooting
Troubleshooting tools
• Logic probe
• Multimeter
College of Nanoscale Science & Engineering
Troubleshooting
Troubleshooting tools• Oscilloscope
• Knowledge of electronic circuits
College of Nanoscale Science & Engineering
Troubleshooting Techniques
Finding where the signal begins Collecting careful and useful data Utilizing test sockets
College of Nanoscale Science & Engineering
Collecting Data
College of Nanoscale Science & Engineering
Test Points
College of Nanoscale Science & Engineering
Circuits of Interest
Switch board• All of the relay switches that refer to mode selection and raster
speeds are controlled on this board
Divider circuit• This circuit creates signals depending on what functions are selected
Logic circuit• Most of the signal timing and synchronization takes place here
College of Nanoscale Science & Engineering
College of Nanoscale Science & Engineering
Challenges
A lot of systems Complex interconnected circuitry Hard to reach components Obsolete Chips
College of Nanoscale Science & Engineering
Challenges
Incomplete documentation
Undocumented after-market modifications
Companies don’t like when people fix things themselves
College of Nanoscale Science & Engineering
Not Completed, However…
Narrowed down possible problem areas
Provided additional data for technicians to review
In storage… for the time being
College of Nanoscale Science & Engineering
What I learned
Differences in theoretical vs experimental analysis• Calculating values • Making practical assumptions
Inner workings of the electron microscope• Understanding of almost any electron microscope circuitry• Most industry standard SEMs function the same way
Troubleshooting complex circuitry• Can take my experience anywhere• Component-wise, electronic circuitry is the same in any device
College of Nanoscale Science & Engineering
Current Work
Transmission electron microscope (TEM)• High voltage power supply appears to be malfunctioning.
College of Nanoscale Science & Engineering
The Problem in More Detail
The problem most likely lies within the Cockcroft – Walton rectification circuit used for voltage amplification
College of Nanoscale Science & Engineering
The Problem
College of Nanoscale Science & Engineering
Special Thanks
Brad Thiel
• Professor (Mentor Extraordinaire) Miguel Rodriguez
• Sr. Technician (The Man) Cathy Dunn
• Professor Lorena Coscio
• Student affairs Tara “The beautiful one” Garcia-
Collins
• Resident assistant Nana “Queens’ finest” Mensah
• Resident assistant
Anthony Weathers
• Cantilever kid Marc-Anthony Armand
• Ion beam certified Marc Carter
• Program Coordinator Carson Carr
• THE MAN You and you and you and you and
especially you
College of Nanoscale Science & Engineering
References Otsuka Tokio
• A Technical Guide for Engineers Using Electron Microscopes• 20, August 1991 Technical Material Dept, JEOL
Museum of Science online• Scanning Electron Microscope http://www.mos.org/sln/sem/intro.html• 1996 Museum of Science
College of Nanoscale Science & Engineering
Ask Now, or Forever Hold Your Piece