1 files changed, 29 insertions, 0 deletions
diff --git a/axial/q_.m b/axial/q_.m
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+%---------------------------------------------------------------
+% Returns the q-factor of a Gaussian beam given the spot size,
+% phasefront radius of curvature and wavelength.
+%
+% SYNTAX: qfactor=q_(w,R <,lambda>);
+%
+% w      = 1/e Field radius 
+% R      = Radius of curvature of phasefront
+% lambda = wavelength
+%
+% Any one of w, R and lambda may be a vectors or scalars.
+% If more than one of w, R and lambda is a vector, all 
+% vectors supplied must be the same size. w, R and lambda must
+% all be in the same units.
+%
+%--------------------------------------------------------------
+% SYNTAX: qfactor=q_(w,R <,lambda>);
+%--------------------------------------------------------------
+
+function qfactor=q_(w,R,varargin)
+
+if nargin>=3, lambda=varargin{1}; else lambda=1064e-9; end
+
+
+if R~=Inf
+    qfactor=pi*w.^2.*R./(pi*w.^2-1i.*R.*lambda);
+else
+    qfactor=1i*pi*w.^2./lambda;
+end
+\ No newline at end of file