
350 OPTICS FOR ENGINEERS
f
x
, pixel
−1
f
y
, pixel
−1
−0.05 0 0.05
−0.05
0
0.05
(A)
−2
0
2
f
x
, pixel
−1
f
y
, pixel
−1
−0.05 0 0.05
−0.05
0
0.05
(B)
−2
0
2
−100
0
100
(C)
0
–0.5
0.5
1
x, Position, pixels
PSF (x,0)
(D)
Figure 11.8 A shifting operation. The coherent OTF (A) consists of a linear phase ramp within
the boundaries of the numerical aperture. The phase shift is by a quarter cycle or π/2 radians
at a frequency of 1/128 per pixel. The incoherent transfer function has a phase with double the
slope of the coherent one (B). The resulting PSFs are shifted in position, but otherwise equivalent
to those of Figure 11.7.
so that the phase shift is π/2 or one quarter cycle at a frequency ...