Automatic commit. Thu Aug 9 17:00:03 WST 2012

[matches/honours.git] / thesis / thesis.tex

diff --git a/thesis/thesis.tex b/thesis/thesis.tex
index d9d64c1..60bcde8 100644 (file)
--- a/thesis/thesis.tex
+++ b/thesis/thesis.tex
@@ -246,7 +246,12 @@ I really think I should actually find plasmonic effects before writing too much
        \end{itemize}
 \end{itemize}
 
-\subsection{Total Current Spectroscopy}
+\subsection{Secondary Electron Spectroscopy}
+
+Secondary electron spectroscopy methods are a broad class of methods which investigate surface electron spectra through observing processes in which the surface electrons participate directly \cite{komolov}. 
+
+Total Current Spectroscopy is a group of electron secondary 
+
 \begin{itemize}
        \item 
        \item Total Current Spectroscopy methods measure the total current of secondary electrons as a function of primary electron energy.
@@ -414,21 +419,27 @@ To simplify circuit diagrams, op-amps will be drawn with the power supply connec
 \subsection*{ADC Inputs}
 The AVR Butterfly offers easy access to four of the ATMega169's ADCs through PORTF. Each ADC is capable of measuring voltages (relative to ground) of $0 < V_{\text{adc}} < V_{cc}$ with 10 Bit resolution. A voltage divider constructed using a variable resistor allows manual adjustment of $V_{\text{adc}}$ so that voltages greater than $V_{cc}$ may still be measured.  Diodes between the ADC input, and $V_{cc}$ and ground, ensure that the ADC is protected from exposure to voltages outside the acceptable range. Figure \ref{fig_ADC_normal} shows the typical input circuit, used for three of the four available ADCs. 
 
-The voltage of the 
+The voltage at the ADC input can be related to the input of the voltage divider using Kirchoff's Voltage Law and Ohm's Law:
 \begin{align*}
  V_{\text{adc}} &= \frac{R_1}{R_1 + R_2} V_{\text{in}}
 \end{align*}
 Where $V_{\text{in}}$ is the voltage at the input of the circuit, $R_1$ is a fixed resistor, and $R_2$ is variable resistor.
 
-The $V_{\text{in}}$ can be determined from the ADC counts by:
+$V_{\text{in}}$ can be determined from ADC counts by:
 \begin{align*}
-       
+       V_{\text{in}} &= \frac{\text{ADC counts}}{2^{10}} \times 
 \end{align*}
 
 
+
 For differential or ``off-ground'' voltage measurements, the fourth ADC input is passed through an instrumentation amplifier. Low pass filters on the input are used to reduce AC noise on the inputs. The buffer amplifiers ensure that negligable current flows through the measurement circuit to ground.
 Figure \ref{fig_ADC5} shows the input circuit for off-ground voltage measurements. It is important to note that the circuit only functions when the input voltages are within the op-amp common-mode voltage range ($\pm15V$).
 
+The output of the instrumentation amplifier can be shown by using Kirchoff's Laws and the ideal model of op-amps to be:
+\begin{align*}
+       V_{\text{diff.}} = \frac{R_2}{R_1} 
+\end{align*}
+
 \subsection*{DAC Output}
 A commercial DAC board was used to produce the DAC output. The Microchip MCP4922 ET-Mini DAC is controlled by the AVR Butterfly using Motorola's Serial Peripheral Interface (SPI) Bus.