From b168bb08f7cebf5eb6d58fb6662e94f57aa1cc84 Mon Sep 17 00:00:00 2001
From: Eugeniy Mikhailov <evgmik@gmail.com>
Date: Fri, 27 Sep 2013 10:50:11 -0400
Subject: bug fixes and improvements in cavity design handling

---
 cavity_design_demo.m | 60 +++++++++++++++++++++++++++++-----------------------
 1 file changed, 33 insertions(+), 27 deletions(-)

(limited to 'cavity_design_demo.m')

diff --git a/cavity_design_demo.m b/cavity_design_demo.m
index 7bddf35..1108f11 100644
--- a/cavity_design_demo.m
+++ b/cavity_design_demo.m
@@ -15,8 +15,8 @@
 
 % let's set some parameters
 R1=0.8;
-R2=1;
-d1=3;
+R2=Inf;
+d1=0.2;
 d2=1;
 Ltot = d1+d2; % total resonator length
 
@@ -29,13 +29,6 @@ lambda = 795e-9;
 
 abcd_cavity = abcd_mirror(R2)*abcd_free_space(d2)*abcd_mirror(R1)* abcd_free_space(d1);
 
-% spelling out abcd coefficients
-A = abcd_cavity(1,1);
-B = abcd_cavity(1,2);
-C = abcd_cavity(2,1);
-D = abcd_cavity(2,2);
-
-
 if ~isCavityStable(abcd_cavity)
     display('Cavity is unstable !');
     display('We should stop now. There is no stable mode in this cavity');
@@ -44,23 +37,23 @@ end
 
 display('Cavity is stable');
 
-% stability parameter see eq.4
-u = (A+D+2)/4;
+zstart = 0;
+qstart = abcd2self_repeating_q( abcd_cavity );
 
-% resonator waist eq.10
-w0 = sqrt ( 2*lambda/(pi*abs(C))*sqrt(u*(1-u)) );
+zfinal = Ltot;
+qfinal = q_after_abcd( qstart, abcd_cavity );
 
-% resonator waist location along 1st arm eq.11
-z0 = (A-D)/(2*C);
 
-% Everything is periodic with respect to cavity length
-% so by taking modulus with respect to its length
-% we get rid of nasty virtual waist condition
-z0 = mod(z0,Ltot);
+eps = 1e-8; % typical round of error
+if ( abs( q2wr(qstart, lambda ) - q2wr(qfinal, lambda) ) > eps )
+    % We should never be here if above functions do their job correctly
+    display(qstart);
+    display(qfinal);
+    error('The calculation is incorrect: resonator mode sizes do not match at the beginning and the end. Go fix the code.');
+end
 
-% naturally the Gaussian beam curvature radius is huge i.e. wavefront is flat
-q0=wr2q(w0, inf, lambda); %Calculate initial q
 
+%% Preparing for the graphical mode output
 % time to build the optics set
 mirror1.abcd = abcd_mirror( R1 ) ;
 mirror1.x = d1;
@@ -75,11 +68,24 @@ show_lens_position = 1; %Set to 1 to enable display of position of center of len
 display_prop = [show_lens_width, show_lens_position];
 
 
-zstart = 0;
-qstart = gbeam_propagation(zstart, q0, z0, optics);
-zfinal = Ltot;
-qfinal = gbeam_propagation(zfinal, q0, z0, optics);
-
 % show beam in the resonator
-[waste_at_the_end, radius_at_the_end, waist_at_mirrors] = solution_visualization(qstart,zstart, qfinal, zfinal, optics, lambda, lens_width, display_prop)
+[waste_at_the_end, radius_at_the_end, waist_at_mirrors] = solution_visualization(qstart,zstart, qfinal, zfinal, optics, lambda, lens_width, display_prop);
+
+waist_at_mirrors
+
+display('Presumed size and location of the cavity waist');
+[w0, z0] = cavity_abcd2its_waist_and_position( abcd_cavity, lambda,  Ltot )
+
+q0_via_propagation = gbeam_propagation ( z0, qstart, zstart, optics );
+[w0prop, R0prop] = q2wr(q0_via_propagation, lambda);
+
+% we expect R0prop to be infinite since it is focused point
+% w0prop should match w0
+
+if ( abs( w0 - w0prop ) > eps )
+    % We should never be here if above functions do their job correctly
+    display(w0prop);
+    error('Different methods to calculate focused point parameters do not match');
+end
+
 
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