OSA's Digital Library

Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 6 — Mar. 25, 2013
  • pp: 7294–7303
« Show journal navigation

Demonstration of a plenoptic microscope based on laser optical feedback imaging

Wilfried Glastre, Olivier Hugon, Olivier Jacquin, Hugues Guillet de Chatellus, and Eric Lacot  »View Author Affiliations


Optics Express, Vol. 21, Issue 6, pp. 7294-7303 (2013)
http://dx.doi.org/10.1364/OE.21.007294


View Full Text Article

Acrobat PDF (981 KB)





Browse Journals / Lookup Meetings

Browse by Journal and Year


   


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools

Share
Citations

Abstract

A new kind of plenoptic imaging system based on Laser Optical Feedback Imaging (LOFI) is presented and is compared to another previously existing device based on microlens array. Improved photometric performances, resolution and depth of field are obtained at the price of a slow point by point scanning. Main properties of plenoptic microscopes such as numerical refocusing on any curved surface or aberrations compensation are both theoretically and experimentally demonstrated with a LOFI-based device.

© 2013 OSA

1. Introduction

In conventional imaging setups, when impacting the detector, only the position of incoming photons is recorded while the information on the angle of arrival is lost. This results in a severe loss of information (stereoscopic information for instance). To handle that problem a first theoretical solution was introduced by the French Nobel Prize Gabriel Lippmann in 1908 under the name “photographie totale” [1

1. G. Lippmann, “Epreuves réversibles. Photographies intégrales,” Comptes Rendus De l'Académie Des Sciences De Paris 146, 446–451 (1908).

], later called “light field” or “plenoptic imaging”. Contrary to classical imaging setups, plenoptic imaging is a technology where both spatial and angular information are recorded. This property leads to unusual features in imaging such as the possibility to numerically refocus a blurry photo after the picture has been taken. This results in an extended depth of field without reducing the aperture of the objective lens and thus there is no need for increasing the exposure time i.e. no movement blurring [2

2. R. Ng, Digital light field photography,” Ph.D. Thesis, University of Standford (2006), http://www.lytro.com/renng-thesis.pdf.

]. The opportunity to correct the objective’s aberrations by digital post-processing has also been demonstrated [3

3. M. Levoy, Z. Zhang, and I. McDowall, “Recording and controlling the 4D light field in a microscope using microlens arrays,” J. Microsc. 235(2), 144–162 (2009), http://graphics.stanford.edu/papers/lfillumination/levoy-lfillumination-jmicr09-lores.pdf. [CrossRef] [PubMed]

]. One of the first experimental device based on a microlens array was presented by Levoy et al. [2

2. R. Ng, Digital light field photography,” Ph.D. Thesis, University of Standford (2006), http://www.lytro.com/renng-thesis.pdf.

,3

3. M. Levoy, Z. Zhang, and I. McDowall, “Recording and controlling the 4D light field in a microscope using microlens arrays,” J. Microsc. 235(2), 144–162 (2009), http://graphics.stanford.edu/papers/lfillumination/levoy-lfillumination-jmicr09-lores.pdf. [CrossRef] [PubMed]

] but suffers from several drawbacks like a low sensitivity and a trade-off between the resolution and the latitude of refocusing.

2. Theoretical background: defocusing

LOFI microscope [4

4. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A 29(8), 1639–1647 (2012). [CrossRef] [PubMed]

] (see Fig. 1
Fig. 1 Experimental setup of the synthetic aperture LOFI-based imaging system. The laser is a 10 mW cw Nd:YVO4 microchip collimated by lens L1. A beam splitter sends 10% output power on a photodiode connected to a lock-in amplifier which gives access to the amplitude and phase of the signal. The frequency shifter is made of two acousto-optic modulators which diffract respectively in orders 1 and −1 and give a round trip total frequency shift of Fe = 3 MHz. x-y plane is scanned by galvanometric mirrors MX (scan in the x direction) and MY (scan in the y direction) conjugated by a telescope made by two identical lenses L3. f3 is the focal lengths of L3. αX and αY are the angular positions of MX and MY. L4 is the objective lens, f4 is its focal distance and r is the final waist of the laser after L4.
) is an ultra-sensitive laser autodyne interferometer imaging technique combining the high accuracy of optical interferometry with the extreme sensitivity of class B lasers to optical feedback [5

5. E. Lacot, O. Jacquin, G. Roussely, O. Hugon, and H. Guillet de Chatellus, “Comparative study of autodyne and heterodyne laser interferometry for imaging,” J. Opt. Soc. Am. A 27(11), 2450–2458 (2010). [CrossRef] [PubMed]

]. Photons are emitted, frequency shifted by a value Fe, retro-reflected by the target and finally reinjected into the laser cavity. In this autodyne method, an optical beating between the reference wave and the signal wave (the light back-reflected by the target) takes place inside the laser cavity. This beating at the frequency shift Fe of the laser is detected by a photodiode and demodulated, leading to amplitude and phase information on the reinjected electric field. Images are obtained because of a point by point scanning by galvanometric mirrors [4

4. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A 29(8), 1639–1647 (2012). [CrossRef] [PubMed]

]. Because one sets the total round-trip frequency shift Fe close to the relaxation frequency of the laser, a large amplification of the optical beating inside the cavity by the laser gain is achieved. More precisely, it was previously shown that the detection is shot noise limited even at low power (~mW) [5

5. E. Lacot, O. Jacquin, G. Roussely, O. Hugon, and H. Guillet de Chatellus, “Comparative study of autodyne and heterodyne laser interferometry for imaging,” J. Opt. Soc. Am. A 27(11), 2450–2458 (2010). [CrossRef] [PubMed]

,6

6. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Deep and optically resolved imaging through scattering media by space-reversed propagation,” Opt. Lett. 37(23), 4823–4825 (2012). [CrossRef] [PubMed]

] which is well suited for the exploration of biological media (no damage and high optical attenuation of the tissues). In addition, because the laser plays the role of both the emitter and the detector it results as a self-aligned and easily transportable device.

When a punctual target located at a distance L from the image plane of the objective is scanned (Fig. 1), one obtains the blurred Point Spread Function (PSF) [4

4. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A 29(8), 1639–1647 (2012). [CrossRef] [PubMed]

]:
hR(L,x,y)=(exp(x2+y2(λLπr)2)exp(j2πx2+y22Lλ))2
(1)
This equation contains information about the spatial position of photons retroreflected by the target (thus a raw blurred image is obtained). By taking the Fourier transform of this expression, one obtains (ν and μ are the spatial frequency coordinates along x and y directions):
HR(L,υ,μ)exp(υ2+μ2(2πr)2)exp(jπLλ(υ2+μ2)2)
(2)
This equation gives an angular information about the retro-reflected photons. Indeed because of the translational scanning, each plane wave contained in the signal is associated with a unique Doppler frequency; each frequency coordinates (ν,μ) corresponds to a plane wave propagating with an angle of λ ν / 2 in the x direction (λ μ / 2 in the y direction) with the optical axis. Finally from Eq. (1) and 2, one can see that information on both the position and the direction of propagation of retroreflected photons is accessible (the wavefront contains a complete information).

On the contrary to classical imaging device (Fig. 2(a)
Fig. 2 (a) Conventional and (b) Plenoptic imaging setup based on microlens array.
) where only the position of impacting photons is recorded (one pixel = one position) by a Charge Coupled Device (CCD), imaging setup showing such properties are called total, light field or plenoptic. A first configuration was presented by Ren Ng et al. in Stanford University [2

2. R. Ng, Digital light field photography,” Ph.D. Thesis, University of Standford (2006), http://www.lytro.com/renng-thesis.pdf.

]. In the case of Ng’s setup (Fig. 2(b)) a microlens array is placed just before the CCD, each microlens covering N pixels. The impacting photons position are thus sampled by each microlens while the angle of arrival of the photon is sampled by the N pixels behind each microlens (see Fig. 2(b)).

This double spatial/angular information allows obtaining images with unusual properties such as the possibility to refocus a blurry image after raw acquisition. Indeed, in a defocused image, photons incoming from a punctual target impact different pixels on the detector instead of arriving at the same pixel. But because they arrive with different angles too (Fig. 2), the image can be numerically refocused by summing these light rays incoming from the target.

In the case of LOFI setup (Fig. 1), the defocus is visible in Eq. (2) in the second term and corresponds to the quadratic phase dependence of the plane waves in the signal. To numerically refocus raw images, this phase has to be cancelled by multiplying the signal in Fourier space (Eq. (2)) by the phase filter Hfilt(L,ν,μ):
Hfilt(L,υ,μ)=exp(jπLλ(υ2+μ2)2)
(3)
This filter corresponds to the free space retropropagation transfer function over a distance L/2 (factor 2 is due to round trip configuration of LOFI, see [4

4. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A 29(8), 1639–1647 (2012). [CrossRef] [PubMed]

]). After filtering and inverse Fourier transform in spatial domain, one has the following final synthetically refocused signal:
|hSA(x,y)|=|TF1(HR(L,υ,μ)Hfilt(L,υ,μ))|=exp(x2+y2(r2)2)
(4)
In this expression TF−1 is the inverse Fourier transform. After numerical refocusing, the resolution is equal to r / √2 whatever is the initial defocus L. As a result the spatial/angular resolution trade-off (and thus the accessible depth of field/spatial resolution) no longer exists. These results are obtained at the price of a lower acquisition speed. Indeed instead of being limited by the CCD rate (around 1 ms for a full field image), one has a slow point by point scanning for LOFI with a 100 μs integration time by pixel (~30 s for a 512*512 pixels image). Beside that there is one last major drawback with LOFI: the photometric balance which degrades with the defocus during raw recording [4

4. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A 29(8), 1639–1647 (2012). [CrossRef] [PubMed]

] (the coupling of the reinjected electric field with the laser cavity acts as a confocal pinhole). This last problem limits the accessible latitude of refocusing but is partially compensated by the ultimate shot noise sensitivity of LOFI [5

5. E. Lacot, O. Jacquin, G. Roussely, O. Hugon, and H. Guillet de Chatellus, “Comparative study of autodyne and heterodyne laser interferometry for imaging,” J. Opt. Soc. Am. A 27(11), 2450–2458 (2010). [CrossRef] [PubMed]

,6

6. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Deep and optically resolved imaging through scattering media by space-reversed propagation,” Opt. Lett. 37(23), 4823–4825 (2012). [CrossRef] [PubMed]

] (this is an important advantage over the low sensitive CCD detector of conventional plenoptic setups).

3. Compensation of aberrations

Aberration compensation is an important concern for imaging through heterogeneous biological media [7

7. R. J. Zawadzki, B. Cense, Y. Zhang, S. S. Choi, D. T. Miller, and J. S. Werner, “Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction,” Opt. Express 16(11), 8126–8143 (2008). [CrossRef] [PubMed]

] or for obtaining highly resolved images with a cheap objective. To correct aberrations, the first solution consists in the introduction of adaptative optics resulting in an aberration-free laser spot in the target plane. Spatial light modulators or deformable mirrors [8

8. A. J. Wright, S. P. Poland, J. M. Girkin, C. W. Freudiger, C. L. Evans, and X. S. Xie, “Adaptive optics for enhanced signal in CARS microscopy,” Opt. Express 15(26), 18209–18219 (2007). [CrossRef] [PubMed]

,9

9. A. Facomprez, E. Beaurepaire, and D. Débarre, “Accuracy of correction in modal sensorless adaptive optics,” Opt. Express 20(3), 2598–2612 (2012). [CrossRef] [PubMed]

] can be used in this way. Another way to handle that problem is to use a plenoptic detector, the compensation is made after the recording of the raw image by a numerical post-processing. This capability has already been demonstrated with conventional plenoptic setups with benefits both in the field of photography [2

2. R. Ng, Digital light field photography,” Ph.D. Thesis, University of Standford (2006), http://www.lytro.com/renng-thesis.pdf.

] as well as in microscopy [3

3. M. Levoy, Z. Zhang, and I. McDowall, “Recording and controlling the 4D light field in a microscope using microlens arrays,” J. Microsc. 235(2), 144–162 (2009), http://graphics.stanford.edu/papers/lfillumination/levoy-lfillumination-jmicr09-lores.pdf. [CrossRef] [PubMed]

]. More precisely, defocus is just one particular second order (relatively to the aperture) aberration; if one totally controls light field rays, there is no reason that higher order aberrations could not been corrected too. In what follows we demonstrate aberration compensation in a LOFI plenoptic imaging setup. To simplify the situation, constant aberration in the image field - i.e. the raw PSF does not depends on the field - is first considered, Eq. (2) is turned into:
HR'(L,υ,μ)=HR(L,υ,μ)Haber(υ,μ)
(5)
In this expression Haber(ν,μ) is the plane waves dephasing term responsible for the aberrations of the optics. In order to both refocus and correct aberrations, the filter function is turned into:
Hfilt'(L,υ,μ)=Hfilt(L,υ,μ)Haber1(υ,μ)
(6)
It seems reasonable to only consider second and third order aberrations for correction; that is to say coma and astigmatism (in addition to defocus). The reason is that for higher order of aberrations the degradation of the PSF is mainly due to the extreme rays in the objective aperture (rays crossing objective lenses far from the center). In our case the laser beam has a Gaussian shape which implies that these aberrant extreme light rays have low amplitude and thus do not impact strongly the final PSF. Finally, with this approximation, the aberrant dephasing term of Eqs. (5) and (6) is now given by the following simplified expression:
Haber(ρ,φ)=Hastig(A,ρ,φ)Hcoma(B,ρ,φ)Hastig(A,ρ,φ)=exp(jAρ2cos(2(φφ0)))Hcoma(B,ρ,φ)=exp(jBρ3cos(φφ0))
(7)
In this expression, ρ and φ are the polar coordinates in the spatial frequency space (the cartesian coordinates are (ν,μ)) and φ0 is the phase origin related to the orientation of coma and astigmatism aberrations relatively to axes x and y. To finish, Hastig, Hcoma, A and B are respectively the dephasing of plane waves due to astigmatism, to coma and the coefficients of these two aberrations.

By comparing Figs. 3(c) and 3(d), an important improvement in the image quality can be observed, which confirms the interest of our numerical aberration compensation technique. However by comparing Figs. 3(d) and 3(e), it is also possible to see that these corrections are not totally perfect. Differences between these images can be essentially explained by higher order non-compensated aberrations.

4. Refocusing on a surface

Getting a sharp image of a 3D object everywhere in the field (i.e. increasing the depth of field while keeping both high resolution and large aperture) is not a new issue. The simplest solution is called focus stacking [11

11. CombineZP (2010), available at http://hadleyweb.pwp.blueyonder.co.uk/CZP/News.htm.

]; in this technique, several images are acquired, each corresponding to a different plane of focus. This stack of images is then computed in order to select in each zone of the field the sharpest image; this results in a globally sharp image everywhere in the field. The problem with that technique is the important amount of time and data resources required. Another solution is the use of non diffractive beam which automatically results in an extended depth of field. Such beams can be obtained with axicons [12

12. Z. Zhai, S. Ding, Q. Lv, X. Wang, and Y. Zhong, “Extended depth of field through an axicon,” J. Mod. Opt. 56(11), 1304–1308 (2009), http://www.tandfonline.com/doi/abs/10.1080/09500340903082689. [CrossRef]

], the accessible depth of focus is however limited by the lens size.

When the ratio laser waist / target distance depends on the field, things are different and the convolution of Eq. (8) of raw defocused image sR(x,y) is now performed with a refocusing filter which changes with the field (L now depends on x and y). More quantitatively, Eq. (8) becomes:
sSA(x,y)=SsR(x0,y0)hfilt(L(x,y),x0x,y0y)dx0dy0
(9)
As stated before, the problem with a direct calculation of Eq. (9) is the excess computation time similar to the convolution product proportional to n2. For example for a 512*512 pixels image it is close to one hour with a 3 GHz dual core processor. In order to reduce computation time, another processing is used: from raw signal, images refocused in several planes spaced by the Rayleigh distance are calculated using quick calculation described in Eqs. (2), (3) and (4). One just has to select in each region of the field the sharpest image exactly like in focus stacking, except that images of the stack are calculated from one raw image. Finally, the computation time is proportional to n log(n) and reduces from one hour down to 30 seconds.

In order to get an experimental demonstration, the object of Fig. 3(a) is used again but now the film where beads are glued is curved in the y direction and simply tilted in the x direction. The objective lens is the same than in Fig. 3(e) (no aberrations). Raw image is presented on Fig. 4(a)
Fig. 4 Demonstration of numerical refocusing on a curved surface. Images size is 512*512 pixels. Target is composed of a curved flexible film with silica bead glued on it (identical to Fig. 2(a). (a) Raw defocused image (250 μm < L < 1000 μm depending on the field). (b) Image after numerical refocusing over a distance 750 μm (on a plane). (c) Calculated surface of refocusing and (d) image after refocusing on this curved plane.
with a defocus comprised between 250 and 1000 μm depending on the field. After numerical refocusing on an intermediate plane corresponding to L = 750 μm (see Fig. 4(b)), one can observe that only a small number of beads are sharp. These sharp beads are distributed along an arc of a circle because of the curved-tilted support film. To conclude Fig. 4(c) shows the best focusing surface and Fig. 4(d) represents the final computed image. In this last image, all beads are sharp despite their initial different positions along optical axis. Because of a Rayleigh distance ZR ~10 μm, the calculation of 50 stack images in intermediate plane is needed.

Once again, the optimal surface of refocusing shown in Fig. 4(c) is calculated locally with the help of the Dubois’s criteria [10

10. F. Dubois, C. Schockaert, N. Callens, and C. Yourassowsky, “Focus plane detection criteria in digital holography microscopy by amplitude analysis,” Opt. Express 14(13), 5895–5908 (2006). [CrossRef] [PubMed]

] (minimization of the sum of pixels amplitude). More precisely, the best refocusing distance is evaluated on four zones in the images and from these measurements, an optimal surface is fitted by a second order polynomial function L(x,y) of equation ax + by2 + cy + d (in x direction, the film is simply tilted) leading to Fig. 4(c). A restriction to the second order is in agreement with the smooth curvature of the target. Of course if the surface were unknown, the best fitting polynomial function could change but the approach would have been the same. However it is noteworthy that low quality bead images are obtained on the edge of Fig. 4(d). This is due to both an incomplete scan of these beads (not all plane waves are present) and to a non perfectly planar laser scan which acts as a phase drift. These two effects results in a degradation [13

13. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Limitations of synthetic aperture laser optical feedback imaging,” J. Opt. Soc. Am. A 29(11), 2247–2255 (2012). [CrossRef] [PubMed]

] of the final image in the radial direction.

5. Conclusion

References and links

1.

G. Lippmann, “Epreuves réversibles. Photographies intégrales,” Comptes Rendus De l'Académie Des Sciences De Paris 146, 446–451 (1908).

2.

R. Ng, Digital light field photography,” Ph.D. Thesis, University of Standford (2006), http://www.lytro.com/renng-thesis.pdf.

3.

M. Levoy, Z. Zhang, and I. McDowall, “Recording and controlling the 4D light field in a microscope using microlens arrays,” J. Microsc. 235(2), 144–162 (2009), http://graphics.stanford.edu/papers/lfillumination/levoy-lfillumination-jmicr09-lores.pdf. [CrossRef] [PubMed]

4.

W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A 29(8), 1639–1647 (2012). [CrossRef] [PubMed]

5.

E. Lacot, O. Jacquin, G. Roussely, O. Hugon, and H. Guillet de Chatellus, “Comparative study of autodyne and heterodyne laser interferometry for imaging,” J. Opt. Soc. Am. A 27(11), 2450–2458 (2010). [CrossRef] [PubMed]

6.

W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Deep and optically resolved imaging through scattering media by space-reversed propagation,” Opt. Lett. 37(23), 4823–4825 (2012). [CrossRef] [PubMed]

7.

R. J. Zawadzki, B. Cense, Y. Zhang, S. S. Choi, D. T. Miller, and J. S. Werner, “Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction,” Opt. Express 16(11), 8126–8143 (2008). [CrossRef] [PubMed]

8.

A. J. Wright, S. P. Poland, J. M. Girkin, C. W. Freudiger, C. L. Evans, and X. S. Xie, “Adaptive optics for enhanced signal in CARS microscopy,” Opt. Express 15(26), 18209–18219 (2007). [CrossRef] [PubMed]

9.

A. Facomprez, E. Beaurepaire, and D. Débarre, “Accuracy of correction in modal sensorless adaptive optics,” Opt. Express 20(3), 2598–2612 (2012). [CrossRef] [PubMed]

10.

F. Dubois, C. Schockaert, N. Callens, and C. Yourassowsky, “Focus plane detection criteria in digital holography microscopy by amplitude analysis,” Opt. Express 14(13), 5895–5908 (2006). [CrossRef] [PubMed]

11.

CombineZP (2010), available at http://hadleyweb.pwp.blueyonder.co.uk/CZP/News.htm.

12.

Z. Zhai, S. Ding, Q. Lv, X. Wang, and Y. Zhong, “Extended depth of field through an axicon,” J. Mod. Opt. 56(11), 1304–1308 (2009), http://www.tandfonline.com/doi/abs/10.1080/09500340903082689. [CrossRef]

13.

W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Limitations of synthetic aperture laser optical feedback imaging,” J. Opt. Soc. Am. A 29(11), 2247–2255 (2012). [CrossRef] [PubMed]

OCIS Codes
(090.0090) Holography : Holography
(110.0110) Imaging systems : Imaging systems
(180.0180) Microscopy : Microscopy

ToC Category:
Microscopy

History
Original Manuscript: December 20, 2012
Revised Manuscript: January 23, 2013
Manuscript Accepted: January 23, 2013
Published: March 15, 2013

Virtual Issues
Vol. 8, Iss. 4 Virtual Journal for Biomedical Optics

Citation
Wilfried Glastre, Olivier Hugon, Olivier Jacquin, Hugues Guillet de Chatellus, and Eric Lacot, "Demonstration of a plenoptic microscope based on laser optical feedback imaging," Opt. Express 21, 7294-7303 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-6-7294


Sort:  Author  |  Year  |  Journal  |  Reset  

References

  1. G. Lippmann, “Epreuves réversibles. Photographies intégrales,” Comptes Rendus De l'Académie Des Sciences De Paris146, 446–451 (1908).
  2. R. Ng, Digital light field photography,” Ph.D. Thesis, University of Standford (2006), http://www.lytro.com/renng-thesis.pdf .
  3. M. Levoy, Z. Zhang, and I. McDowall, “Recording and controlling the 4D light field in a microscope using microlens arrays,” J. Microsc.235(2), 144–162 (2009), http://graphics.stanford.edu/papers/lfillumination/levoy-lfillumination-jmicr09-lores.pdf . [CrossRef] [PubMed]
  4. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Synthetic aperture laser optical feedback imaging using a translational scanning with galvanometric mirrors,” J. Opt. Soc. Am. A29(8), 1639–1647 (2012). [CrossRef] [PubMed]
  5. E. Lacot, O. Jacquin, G. Roussely, O. Hugon, and H. Guillet de Chatellus, “Comparative study of autodyne and heterodyne laser interferometry for imaging,” J. Opt. Soc. Am. A27(11), 2450–2458 (2010). [CrossRef] [PubMed]
  6. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Deep and optically resolved imaging through scattering media by space-reversed propagation,” Opt. Lett.37(23), 4823–4825 (2012). [CrossRef] [PubMed]
  7. R. J. Zawadzki, B. Cense, Y. Zhang, S. S. Choi, D. T. Miller, and J. S. Werner, “Ultrahigh-resolution optical coherence tomography with monochromatic and chromatic aberration correction,” Opt. Express16(11), 8126–8143 (2008). [CrossRef] [PubMed]
  8. A. J. Wright, S. P. Poland, J. M. Girkin, C. W. Freudiger, C. L. Evans, and X. S. Xie, “Adaptive optics for enhanced signal in CARS microscopy,” Opt. Express15(26), 18209–18219 (2007). [CrossRef] [PubMed]
  9. A. Facomprez, E. Beaurepaire, and D. Débarre, “Accuracy of correction in modal sensorless adaptive optics,” Opt. Express20(3), 2598–2612 (2012). [CrossRef] [PubMed]
  10. F. Dubois, C. Schockaert, N. Callens, and C. Yourassowsky, “Focus plane detection criteria in digital holography microscopy by amplitude analysis,” Opt. Express14(13), 5895–5908 (2006). [CrossRef] [PubMed]
  11. CombineZP (2010), available at http://hadleyweb.pwp.blueyonder.co.uk/CZP/News.htm .
  12. Z. Zhai, S. Ding, Q. Lv, X. Wang, and Y. Zhong, “Extended depth of field through an axicon,” J. Mod. Opt.56(11), 1304–1308 (2009), http://www.tandfonline.com/doi/abs/10.1080/09500340903082689 . [CrossRef]
  13. W. Glastre, O. Jacquin, O. Hugon, H. Guillet de Chatellus, and E. Lacot, “Limitations of synthetic aperture laser optical feedback imaging,” J. Opt. Soc. Am. A29(11), 2247–2255 (2012). [CrossRef] [PubMed]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.

Figures

Fig. 1 Fig. 2 Fig. 3
 
Fig. 4
 

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited