function f = land(v) % f = land(v) % % is a defect function for the design of a landscape lens. % % The variables are % % v(1) = first surface curvature % v(2) = distance to stop % % The defects are % % f(1) = coma % f(2) = astigmatism % Written by: John S. Loomis, University of Dayton % Revision: 8 Feb 2003 global cv th rn; cv(2)=v(1); % first surface curvature th(3)=v(2); % distance to stop yap = 5.0; uco = tan(10*pi/180); scl = yap^2/2; ya = parax([yap 0],cv,th,rn); usolve = -0.125; m=3; yn=ya(m,1); if (abs(yn)>1e-6) cv(m)= -(rn(m)*usolve-rn(m-1)*ya(m-1,2))/((rn(m)-rn(m-1))*yn); end ya(m,2)=usolve; ya = parax([yap 0],cv,th,rn); yc = parax([0 uco],cv,th,rn); k = -yc(4,1)/ya(4,1); yc = yc + k*ya; lambda = 0.006; w = ford(ya,yc,cv,th,rn,lambda); f(1) = w(2); % coma f(2) = w(3); % astigmatism f = f';