Handbook of Biomedical Optics

Application of Digital Holographic Microscopy in Biomedicine 627

|O|

2

(k

x

,k

y

) is more problematic because it depends on the spec-

trum of the object itself: O(k

x

,k

y

) which is supposed to naturally

or intentionally limited by the NA of the objective or more gen-

erally by the pupil of the optical setup. |O|

2

(k

x

,k

y

) is, mathemati-

cally, equal to the autocorrelation of the spatial spectrum of

the object wave O(k

x

,k

y

). It also provides the spectral density of

the object wave in the (k

x

,k

y

) domain. In the case of a mono-

chromatic illumination, the spatial spectrum is limited, usu-

ally by instrumental considerations, when a limiting apert