diff options
Diffstat (limited to 'abcd.m')
| -rw-r--r-- | abcd.m | 85 |
1 files changed, 75 insertions, 10 deletions
@@ -10,23 +10,30 @@ function qnew=q_afteer_element(q_old,abcd) qnew=(q_old*abcd(1,1)+abcd(1,2))/(q_old*abcd(2,1)+abcd(2,2)); endfunction -function q = prop(x_pos, q_in, elements) +function q = prop_forward(x_pos, q_in, x_in, optics_elements) % calculate the 'q' parameter of the Gaussian beam propagating through optical -% 'elements' array along 'x' axis at points 'x_pos' -% takes the gaussian beam with initial q_in parameter at x_pos(1) +% 'optics_elements' array along 'x' axis at points 'x_pos' +% takes the gaussian beam with initial q_in parameter at x_in +% +% all x_pos must be to the right of x_in + if (any(x_pos < x_in)) + error('all beam positions must be to the right of the x_in'); + end + optics_elements=arrange_optics_along_x(optics_elements); + + % Forward propagation to the right of x_in Np=length(x_pos); % number of 'x' points - Nel=length(elements); + Nel=length(optics_elements) ; q=0*x_pos; % q vector initialization - q(1)=q_in; q_last_calc=q_in; - x_last_calc=x_pos(1); % the furthest calculated point - for i=2:Np + x_last_calc=x_in; % the furthest calculated point + for i=1:Np x_pos_i=x_pos(i); - for k=1:length(elements) - % iterates through optical elements to make sure + for k=1:length(optics_elements) + % iterates through optics_elements to make sure % we take them in account for the beam propagation - el=elements{k}; + el=optics_elements{k}; if ( (x_last_calc < el.x) && (el.x <= x_pos_i) ) abcd=abcd_free_space(el.x-x_last_calc); q_last_calc=q_afteer_element(q_last_calc,abcd); @@ -41,6 +48,64 @@ function q = prop(x_pos, q_in, elements) endif q(i)=q_last_calc; endfor +end + +function optics = arrange_optics_along_x(optics_unsorted) +% arrange optics in proper order so it x position increases with number + N=length(optics_unsorted); + + % assign x positions + x=zeros(1,N); + for i=1:N + x(i)=optics_unsorted{i}.x; + end + + [xs,indx]=sort(x); + cntr=1; + for i=indx + optics{cntr}=optics_unsorted{i}; + cntr=cntr+1; + end +end + +function q = prop(x_pos, q_in, x_in, optics_elements) +% calculate the 'q' parameter of the Gaussian beam propagating through optical +% 'optics_elements' array along 'x' axis at points 'x_pos' +% takes the gaussian beam with initial q_in parameter at x_in + + q=0*x_pos; % q vector initialization + + if any(x_pos >= x_in) + % Forward propagation to the right of x_in + q(x_pos >= x_in) = prop_forward(x_pos(x_pos>=x_in), q_in, x_in, optics_elements); + end + + if any(x_pos < x_in) + % Backward propagation part the left of x_in + % do it as forward propagation of the reverse beam + x_backw=x_pos(x_pos<x_in); + % now let's reflect the beam with respect to x_in + % and solve the problem as forward propagating. + x_backw=x_in-x_backw; + % now we need to flip x positions + x_backw=fliplr(x_backw); + % reflected beam means inverted radius of curvature or real part of q parameter + q_in_backw = -real(q_in) + 1i*imag(q_in); + optics_elements_backw=optics_elements; + % we need to flip all optics elements around x_in as well + for i=1:length(optics_elements_backw) + optics_elements_backw{i}.x=x_in-optics_elements_backw{i}.x; + end + + q_backw = prop_forward(x_backw, q_in_backw, 0, optics_elements_backw); + % now we need to flip the radius of curvature again + q_backw = -real(q_backw) + 1i*imag(q_backw); + + % final assignment of the backwards propagating beam + % which we need to flip back + q(x_pos<x_in) = fliplr(q_backw); + end + endfunction function waste =q2waste(q, lambda) |