% NAFN plots f number as a function of numerical aperture. % % by Chuck DiMarzio % Northeastern University % March 2009 % % !! This file may be copied, used, or modified for educational and % !! research purposes provided that this header information is not % !! removed or altered, and provided that the book is cited in % !! publications, as DiMarzio, Charles A., Optics for Engineers, % !! CRC Press, Boca Raton, FL, 2011. % !! http://www.crcpress.com % !! Other distribution is prohibited without permission. % % theta=(0:90); na=sind(theta); fn=1/2./tand(theta); fnapprox=1/2./na; test=find(fn<4); fig1=figure(1); plot(na(test),fn(test),'-',na(test),fnapprox(test),'--'); grid on; xlabel('NA'); ylabel('F-Number'); omega=2*pi*(1-sqrt(1-na.^2)); omegaapprox=pi*na.^2; fig2=figure(2);plot(na,omega,'-',na,omegaapprox,'--');grid on; xlabel('NA'); ylabel('\Omega, sr');

