description de l'appareillage

[dmems12.git] / dmems12.tex

diff --git a/dmems12.tex b/dmems12.tex
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--- a/dmems12.tex
+++ b/dmems12.tex
@@ -71,12 +71,78 @@
 
 \section{Introduction}
 
 
 \section{Introduction}
 

-%% blabla +
+Cantilevers  are  used  inside  atomic  force  microscope  which  provides  high
+resolution images of  surfaces.  Several technics have been  used to measure the
+displacement  of cantilevers  in litterature.   For example,  it is  possible to
+determine  accurately  the  deflection  with different  mechanisms. 
+In~\cite{CantiPiezzo01},   authors  used   piezoresistor  integrated   into  the
+cantilever.   Nevertheless this  approach  suffers from  the  complexity of  the
+microfabrication  process needed  to  implement the  sensor  in the  cantilever.
+In~\cite{CantiCapacitive03},  authors  have  presented an  cantilever  mechanism
+based on  capacitive sensing. This kind  of technic also  involves to instrument
+the cantiliver which result in a complex fabrication process.
+
+In this  paper our attention is focused  on a method based  on interferometry to
+measure cantilevers' displacements.  In  this method cantilevers are illuminated
+by  an optic  source. The  interferometry produces  fringes on  each cantilevers
+which enables to  compute the cantilever displacement.  In  order to analyze the
+fringes a  high speed camera  is used. Images  need to be processed  quickly and
+then  a estimation  method is  required to  determine the  displacement  of each
+cantilever.  In~\cite{AFMCSEM11},  the authors have  used an algorithm  based on
+spline to estimate the cantilevers' positions.
+%%RAPH : ce qui est génant c'est qu'ils ne parlent pas de spline dans ce papier...
+   The overall  process gives
+accurate results  but all the computation  are performed on  a standard computer
+using labview.  Consequently,  the main drawback of this  implementation is that
+the computer is a bootleneck in the overall process. In this paper we propose to
+use a  method based on least  square and to  implement all the computation  on a
+FGPA.
+
+The remainder  of the paper  is organized as  follows. Section~\ref{sec:measure}
+describes  more precisely  the measurement  process. Our  solution based  on the
+least  square   method  and   the  implementation  on   FPGA  is   presented  in
+Section~\ref{sec:solus}.       Experimentations      are       described      in
+Section~\ref{sec:results}.  Finally  a  conclusion  and  some  perspectives  are
+presented.
+
+
+

 %% quelques ref commentées sur les calculs basés sur l'interférométrie
 
 \section{Measurement principles}
 \label{sec:measure}
 
 %% quelques ref commentées sur les calculs basés sur l'interférométrie
 
 \section{Measurement principles}
 \label{sec:measure}
 

+In order to develop simple,  cost effective and user-friendly cantilever arrays,
+authors   of    ~\cite{AFMCSEM11}   have   developped   a    system   based   of
+interferometry. In opposition to other optical based systems, using a laser beam
+deflection scheme and  sentitive to the angular displacement  of the cantilever,
+interferometry  is sensitive  to  the  optical path  difference  induced by  the
+vertical displacement of the cantilever.
+%%RAPH : est ce qu'on pique une image? génant ou non?
+The system build  by authors of~\cite{AFMCSEM11} has been  developped based on a
+Linnick interferomter~\cite{Sinclair:05}.   A laser beam is first  split (by the
+splitter) into  a reference beam  and a sample  beam that reachs  the cantilever
+array.  In  order to be able  to move the cantilever  array, it is  mounted on a
+translation  and rotational  stage with  five  degrees of  freedom. The  optical
+system is also fixed to the stage. Thus, the cantilever array is centered in the
+optical system which can be adjusted accurately.  The beam illuminates the array
+by a  microscope objective and the  light reflects on  the cantilevers. Likewise
+the reference beam reflects on a movable mirror.  A CMOS camera chip records the
+reference and  sample beams which  are recombined in  the beam splitter  and the
+interferogram. At the beginning of each experiment, the movable mirror is fitted
+manually in order to align the interferometric fringes approximately parallel to
+the  cantilevers. When  cantilevers  move due  to  the surface,  the bending  of
+cantilevers produce movements in the fringes  that can be detected with the CMOS
+camera.  Finally  the fringes  need  to  be  analyzed. In~\cite{AFMCSEM11},  the
+authors used  a LabView program to  compute the cantilevers'  movements from the
+fringes.
+
+
+
+
+
+
+

 \subsection{Architecture}
 \label{sec:archi}
 %% description de l'architecture générale de l'acquisition d'images
 \subsection{Architecture}
 \label{sec:archi}
 %% description de l'architecture générale de l'acquisition d'images


@@ -328,9 +394,9 @@ Finally, the whole summarizes in an algorithm (called LSQ in the following) in t
 
 \subsubsection{Comparison}
 
 
 \subsubsection{Comparison}
 

-\subsection{VDHL design paradigms}
+\subsection{VHDL design paradigms}

 
 

-\subsection{VDHL implementation}
+\subsection{VHDL implementation}

 
 \section{Experimental results}
 \label{sec:results}
 
 \section{Experimental results}
 \label{sec:results}