Fig. 1. Optical configuration of FINCH with an RMBDL.

Fig. 2. PSH library generation, object hologram recording, and computational reconstruction.The blue regions in reconstruction results indicate the areas with the best focus. The point spread holograms are recorded once as images, and the object hologram is recorded. The images in CMYK format were converted into 8-byte data and filtered computationally using low-pass filter, non-linear filter and median filter.

Fig. 3. Optical microscope images of the fabricated RMBDL.

Fig. 4. Images of the PSHs recorded for Δz₁ = (a) -3 cm, (b) -2.5 cm, (c) -2 cm, (d) -1.5 cm, (e) -1 cm, (f) -0.5 cm, (g) 0.5 cm, (h) 1 cm, (i) 1.5 cm, (j) 2 cm, (k) 2.5 cm, (l) 3 cm and (m) 0 cm. (n) Plot of the variation of I_R (x=0, y=0) as a function of Δz₁.

Fig. 5. (a) Direct imaging result of the USAF object recorded at z₂=5 cm. (b) FINCH hologram of the USAF object. Reconstruction results using (c) Lucy-Richardson algorithm (250 iterations), (d) Weiner filter, (e) Fresnel back propagation and (f) non-linear filter (α=0.2, β=0.6). (g) Optical microscope image of of the stained biological sample. The area within the rectangular red box was used for the experiments while the rest of the area was masked with a black tape. (h) Magnified image of the sample within the red box. (i) The direct imaging result with the RMBDL recorded at z₂=5 cm from the RMBDL. (j) Object hologram. Reconstruction results using (k) non-linear filter (α=0.2, β=0.6) and (l) Lucy-Richardson algorithm (250 iterations). (m) Plots of the normalized, average intensity values of the grating images of direct imaging (blue), non-linear correlation (green) and Lucy-Richardson algorithm (red) with an average visibility values of 0.504, 0.85 and 0.64 respectively. The different colour dotted circles compare identical areas in different reconstructions. It is seen that the direct imaging results could not resolve features as effectively as FINCH.

Fig. 6. (a) Ideal image synthesized from the direct imaging result. (b) Autocorrelation image of (a). Results of (c) cross-correlation between (a) and Fig. 5 (a), (d) cross-correlation between (a) and Fig. 5 (f), and (e) cross-correlation between (a) and Fig. 5 (c). (f) Plots of the horizontal line data along the origin for (b)–(e). The extracted line data is shown using white dotted line. SSIM index maps calculated by comparing the ideal image with (g) ideal image, (h) direct imaging, (i) FINCH by non-linear reconstruction and (j) FINCH by Lucy-Richardson algorithm.

Fig. 7. Images of the (a) PSH and (b) object hologram of Elements 5 and 6 of Group 5. (c) Direct imaging result of elements 5 and 6 of group 5 and (d) normalized average visibility plot of the gratings. Reconstruction results from (e) non-linear filter and Lucy-Richardson algorithm (g) 150 iterations and (i) 200 iterations. Normalized average plot of the gratings for (f) non-linear filter, Lucy-Richardson algorithm (h) 150 iterations and (j) 200 iterations.

Fig. 8. (a) Image of the hologram of the two plane object. Point spread holograms recorded at (b) z₁ = 4.5 cm and (c) z₂ = 5 cm. Reconstruction results: USAF is at z = 4.5 cm and NBS is at z = 5 cm from the RMBDL and reconstructed using the PSH (z₁ = 4.5 cm), (d) Lucy-Richardson algorithm and (e) non-linear reconstruction. The reconstruction results of the object hologram using the PSH (z₁ = 5 cm), (f) Lucy-Richardson algorithm and (g) non-linear reconstruction.