Numerical Aperture NA=n(sin a) Oil Immersion and Numerical aperture Imaging Medium Objective Numerical Aperture Comparison Air n=1.0 NA.=0.25 5 NA.=0.75 345 Immersion oil n=1.515 http://ww.youtube.com/watch?v=rskb0j1srnu oil immersion objective use in microscope at0: 33Numerical Aperture Immersion oil n=1.515 Air n=1.0 http://www.youtube.com/watch?v=RSKB0J1sRnU oil immersion objective use in microscope at~0:33 Imaging Medium NA = n(sin )