function optics = arrange_optics_along_x(optics_unsorted)
% arrange optics in proper order so its x position increases with consequent index
	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