Handbook of Biomedical Optics

498 Handbook of Biomedical Optics

phase contrast microscopy can be computed from the Fourier

transform of this modied exit pupil function that results in

h x y ja k x y k x y

PC ic

( , ) [ ( , ) ( , )]= ± −

where it is assumed that the outer diameter of the phase ring

coincides with that of the system’s exit pupil and that the Fourier

transform of the outer circle is equal to the amplitude PSF for

bright-eld microscopy. k

ic

(x, y) is dened as the Fourier trans-

form of the inner circle of the ring. As discussed in Section

24.2.2.2, the illumination is also modied by the condenser

annulus that consists of an opaque circular plate