Synthetic Aperture Lensless Digital Holographic Microscopy (SALDHM) for Superresolved Biological Imaging - Biomedical Optical Phase Microscopy and Nanoscopy - page 181

(A) (B)

(C)

(D)

Figure 9.9
(A) Recovered bandpass images of the proposed SALDHM incoming from on-axis (central image)
and off-axis (four outer images) illuminations: (B) generated SA, (C) superresolved image, and (D)
magnified area of the inner part marked with a solid white line rectangle in case (C). The off-axis
illuminations are provided by the second illumination ring.

addition of a new rectangular pupil. This second illumination ring is produced by combining
two identical wedge prisms like in a beam steering application. With this procedure, a set of
tilted beams having an oblique illumination angle of 20 are produced over the input plane
defining our second illumination ring. The new set of bandpass images (outer images)
provided by the second illumination ring is included in Figure 9.9A , in addition again with the
one obtained using the on-axis illumination (inner image). The SA incoming from the addition
of the eight off-axis elementary apertures plus the on-axis one is presented in Figure 9.9B .And
finally, the superresolved image is included in Figure 9.9C while a magnification of its central
part is depicted in Figure 9.9D . We can see that the three last elements of the test target are
resolved in both H and V directions for the superresolved image.

According to the theory, the SNA and the superresolution limits in H and V directions are
given by SNA HOR 5 0.45 and SNA VER 5 0.42, and SR HOR 5 1.41 μ m (709 lp/mm) and