Fig 1.
Illustration of super-resolution imaging modes.
(A) virtual imaging mode; and (B) real imaging mode.
Fig 2.
Blu-ray disc sample observed using different methods and conditions.
(A) image captured with a 100x (N.A. 0.9) objective lens; (B) image captured with a 30-μm PS microsphere with (B-1) a 20x (N.A. 0.75) objective lens, and (B-2) a 50x (N.A. 0.45) objective lens; (C) results using AFM; (D) image captured with a 25-μm BTG microsphere with (D-1) a 20x (N.A. 0.75) objective lens, and (D-2) a 50x (N.A. 0.45) objective lens. The values on top of each scale bar represents the scale bar’s length that is estimated in real object scale.
Fig 3.
Color images of a Blu-ray disc captured under different conditions.
(A) 65-μm BTG, (B) 90-μm BTG, and (C) 175-μm BTG. All images were captured using a 50x (NA 0.45) objective lens. All scale bars represent 20 μm without including the microsphere’s additional magnification. The value on top of each scale bar represents the scale bar’s length that is estimated in the real object scale.
Fig 4.
Comparison of images of CPU (22-nm lithography CPU: Intel G2010) features captured in different ways.
(A) CPU observed with a 100x (NA 0.9) objective lens, where subset (A-1) shows the magnified area of interest; and (B) the same location of the CPU as in (A) observed through a 200-μm diameter BTG microsphere with a 100x (NA 0.9) objective lens. The smallest gap width resolved in (B) is estimated to be 120 nm wide. (C) a second location observed with a100x (NA 0.9) objective lens, where subset (C-1) shows the magnified area of interest; (D) a 25-μm diameter PS microsphere with a 100x (NA 0.9) objective lens observing on the features in (C); (E) SEM image of the same features in (C) at 30 kV; (F) a 15-μm diameter BTG microsphere with a 100x (NA 0.9) objective lens; and (G) same condition as (F) but captured with a color camera. The value on top of each scale bar represents the scale bar’s length in real object scale. The additional magnification factors for (B), (D), (F) and (G) are estimated to be 6.44x, 6.92x, 5.62x and 6.33x, respectively, using the proposed method mentioned later in this article.
Fig 5.
2D simulation using FDTD, displaying Poynting vector magnitudes and directions as colors and streamlines, respectively, for different combination of refractive index n and the size of the microsphere in radius R.
(A) n = 1.59, R = 12.5 (B) n = 1.9, R = 12.5 (C) n = 1.59, R = 5 (D) n = 1.9, R = 5. For all conditions, a dipole excitation is located at the coordinate of (0.5, -10), which is of 500nm horizontal offset to the bottommost point of the microsphere at (0, -10). The unit of the coordinates is in micrometer. The location of the dipole excitation and orientation is indicated in the inset in (A).
Fig 6.
Extrapolated linear fits of the top segments (i.e., segments from 80 to 130 μm) of the Poynting streamlines with different refractive indices and microsphere sizes.
(A) n = 1.59, R = 12.5 (B) n = 1.9, R = 12.5 (C) n = 1.59, R = 5 and (D) n = 1.9, R = 5.
Fig 7.
Blu-ray disc samples observed with different microsphere sizes at different focus positions (Z).
Focus positions descend with the row they are located in. All scale bars represent 20 μm without including the microsphere’s additional magnification. All images are captured using a 50x (NA 0.45) objective lens, except for the rightmost column. The value on top of each scale bar represents the scale bar’s length that is estimated in the real object scale.
Fig 8.
Cross-section slice of z-stacked images captured under different conditions.
(A) a 50x (NA 0.45) objective lens with a 25-μm BTG; (B) a 50x (NA 0.45) objective lens with a 65-μm BTG; (C) a 50x (NA 0.45) objective lens with a 175-μm BTG; and (D) a 50x (NA 0.45) objective lens with a 220-μm BTG. Subsets (A-1), (B-1), (C-1), (D-1) correspond to subfigures (A)-(D), where each shows the cutting line that results in the cross-section slice. Similarly, the dotted line in each cross-section slice shows the focus position when capturing the corresponding subset. All X-axes use the objective lens’ scale.
Fig 9.
Cross-section slice of the z-stacked images captured under different conditions.
(A) a 20x (NA 0.75) objective lens with a 220-μm BTG; (B) a 20x (NA 0.45) objective lens with a 220-μm BTG; and (C) a 10x (NA 0.3) objective lens with a 220-μm BTG. Subsets (A-1), (B-1), and (C-1) correspond to subfigures (A)-(C), where each shows the cutting line that results in the cross-section slice. Similarly, the dotted line in each cross-section slice shows the focus position when capturing the corresponding subset. All X-axes use the objective lens’ scale.
Fig 10.
Results obtained from the cross-section of z-stacked images.
(A) first difference of the cross-section of z-stacked images, where inset (A-1) shows the original cross-section using a 220μm diameter BTG; (B) Zoom FFT Analysis of (A), where the magnitude of the frequency is represented by its color; (C) magnification analysis of (B); (D) magnification analysis on 25μm diameter BTG; (E) magnification analysis on 65μm diameter BTG; (F) magnification analysis obtained on 175μm diameter BTG. The strength of the magnification is represented by the color. The results are all obtained using a 50x (NA 0.45) objective lens.
Fig 11.
Plot of the theoretical and experimental magnification using different sizes of microspheres against the z-position.