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1.
Fig. 4

Fig. 4. From: Field-portable lensfree tomographic microscope.

(a–c) Comparison of the line profiles along z, x and y, respectively, through the centre of a 2 μm diameter micro-particle image, obtained by reconstructing a single LR hologram (blue curves), an SR hologram (red curves) and by tomographic reconstruction (green curves).

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.
2.
Fig. 7

Fig. 7. From: Field-portable lensfree tomographic microscope.

(a1–a3) The computed tomograms for different depths of a H. nana egg, which can also be compared against 40× microscope images shown in (b1–b3). See Video S4 for other depth sections of the same egg, which suggest a total thickness of ~40 μm, very well matching with its diameter.

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.
3.
Fig. 2

Fig. 2. From: Field-portable lensfree tomographic microscope.

(a1–a3) Our hologram recording geometry is illustrated for three different angles of θ = −44°, 0° and 44°. (b1–b3) Pixel super-resolved (SR) projection holograms for the corresponding angles are shown. These holograms are cropped from a much larger FOV of ~24 mm2. (c1–c3) Projection images obtained by reconstructing the SR holograms shown in (b1–b3) are shown for the corresponding angles. These projections are aligned to each other with respect to the bead at the centre of the images.

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.
4.
Fig. 3

Fig. 3. From: Field-portable lensfree tomographic microscope.

(a) A measured low-resolution (LR) vertical projection hologram for 2 μm diameter micro-particles. (b) The digitally synthesized pixel super-resolved (SR) hologram for the same region, where holographic fringes with much higher frequencies can be observed, that are normally undersampled in (a). (a1 and a2) The yz and xz cross-sections for a micro-particle obtained by reconstructing the LR hologram in (a). (a3) The reconstructed image of the same micro-particle in xy plane using the LR hologram shown in (a). (b1 and b2) The yz and xz cross-sections for the same micro-particle obtained by reconstructing the SR hologram in (b). (b3) The reconstructed image of the micro-particle in xy plane using SR hologram shown in (b). (c1–c3) The sectional images (tomograms) through the centre of the micro-particle in yz, xz and xy planes, respectively.

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.
5.
Fig. 6

Fig. 6. From: Field-portable lensfree tomographic microscope.

The tomographic imaging performance for a multilayer chamber (mounted with 0.7 mm elevation above the sensor) of 10 μm beads, suspended over 4 layers with a total thickness of ~3.5 mm. (a) A recorded hologram of this multi-layer object, where the holograms of beads at different depths are visible (with varying sizes as a function of the distance from the sensor-chip). (b1–b3) Digitally cleaned holograms, which comprise the information of objects in only a selected layer, are shown (see the Methods section for details). (c1–c5) Computed tomograms for different depths are shown to demonstrate depth sectioning over a large DOF of ~4.2 mm.

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.
6.
Fig. 1

Fig. 1. From: Field-portable lensfree tomographic microscope.

A photograph (left) and a schematic diagram (right) of the field-portable lensfree tomographic microscope (weighing ~110 grams) are shown. 24 LEDs are butt-coupled to individual optical fibres, which are mounted along an arc to provide multi-angle illumination within a range of ±50°. LEDs are sequentially turned on by a micro-controller to record projection holograms of the objects. At each angle, multiple sub-pixel shifted holograms are recorded to synthesize projection holograms with enhanced numerical aperture and resolution. These holograms are digitally processed to first obtain projection images, and then to compute tomograms with <7 μm axial resolution over a large sample volume of ~20 mm3 on a chip.

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.
7.
Fig. 5

Fig. 5. From: Field-portable lensfree tomographic microscope.

(a1–a5) The microscope images (40×, 0.65-NA) for different depth sections of a chamber filled with randomly distributed micro-beads with 5 μm diameter. (b1–b5) Our lensfree computed tomograms for the corresponding layers, which demonstrate successful depth sectioning with our tomographic microscope. The arrows in each image show the beads that are in-focus at a given depth. (c) A zoomed tomographic image through the centre of an arbitrary bead together with its line profiles along x and y. (d) The axial line profile and its derivative for the same bead as in (c), suggesting an axial resolution of ~6 μm. The inset in the figure, enclosed with the dashed rectangle, shows sectioning of two axially overlapping micro-beads, shown by the dashed circles in (a1) and (b5), both by lensfree tomography and conventional microscopy (40×, 0.65-NA). Notice that at z = 12 μm plane (shown at the centre of this inset) our lensfree tomographic image does not show anything since z = 12 μm refers to the depth layer that is between the two axially overlapping beads. This provides an independent validation for our significantly improved depth resolving capability. See Video S3 for tomograms of other depth sections within the full FOV of the sensor-array.

Serhan O. Isikman, et al. Lab Chip. ;11(13):2222-2230.

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