Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group

Refractive index tomography of turbid media by bifocal optical coherence refractometry

Open Access Open Access

Abstract

We demonstrate tomographic imaging of the refractive index of turbid media using bifocal optical coherence refractometry (BOCR). The technique, which is a variant of optical coherence tomography, is based on the measurement of the optical pathlength difference between two foci simultaneously present in a medium of interest. We describe a new method to axially shift the bifocal optical pathlength that avoids the need to physically relocate the objective lens or the sample during an axial scan, and present an experimental realization based on an adaptive liquid-crystal lens. We present experimental results, including video clips, which demonstrate refractive index tomography of a range of turbid liquid phantoms, as well as of human skin in vivo.

©2003 Optical Society of America

Full Article  |  PDF Article
More Like This
Bifocal optical coherenc refractometry of turbid media

Sergey A. Alexandrov, Andrei V. Zvyagin, K. K. M. B. Dilusha Silva, and David D. Sampson
Opt. Lett. 28(2) 117-119 (2003)

Noncontact optical tomography of turbid media

Ralf B. Schulz, Jorge Ripoll, and Vasilis Ntziachristos
Opt. Lett. 28(18) 1701-1703 (2003)

Characterizing refractive index and thickness of biological tissues using combined multiphoton microscopy and optical coherence tomography

Yifeng Zhou, Kenny K. H. Chan, Tom Lai, and Shuo Tang
Biomed. Opt. Express 4(1) 38-50 (2013)

Supplementary Material (5)

Media 1: AVI (773 KB)     
Media 2: AVI (1157 KB)     
Media 3: AVI (517 KB)     
Media 4: AVI (313 KB)     
Media 5: AVI (358 KB)     

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (9)

Fig. 1.
Fig. 1. Schematic diagram of the BOCR system showing the sample arm in detail. LC: liquid-crystal lens; GM: galvanometer-mounted tiltable mirror; Lobj: objective lens.
Fig. 2.
Fig. 2. Schematic diagram of the bifocal optical arrangement in the sample arm showing rays for the cases n=1 (dashed) and n>1 (solid).
Fig. 3.
Fig. 3. (a), (b) (773 KB) Video clip (not real time, 234 OCT frames per video frame) of shifting the bifocal gate through an aqueous solution of Intralipid. Separate frames are shown in (a) and (b). GCS, glass cover slip surface; BFG, Bifocal gate signal. Scale bars represent optical pathlength. (c) Average axial profile from the images in (a) and (b), and its theoretical fit.
Fig. 4.
Fig. 4. Refractive-index tomogram (combined mesh and color plots) of a homogeneous Intralipid aqueous solution (corresponding to Fig. 3(a), (b)).
Fig. 5.
Fig. 5. (1157 KB) Video clip (not real time, 234 OCT frames per video frame) of the scan of one focus of the bifocal gate. An indicator in the top left corner gives the focal length of the liquid-crystal lens. Scale bar represents optical pathlength.
Fig. 6.
Fig. 6. (a) (517 kB) Video clip (not real time, 60 OCT frames per video frame) of the bifocal-gate scan and schematic diagram of the two-layer sample. (Two montaged frames are shown in the figure and the scale bar represents optical pathlength). (b) Combined mesh and color plots of the refractive index determined from the data set displayed in (a).
Fig. 7.
Fig. 7. Average refractive index versus axial depth of the heterogeneous sample.
Fig. 8.
Fig. 8. (a) (313 kB) Video clip (not real time, 60 OCT frames per video frame) of the bifocal gate scan versus sugar concentration in the Intralipid aqueous solution. Scale bar represents optical pathlength. (b) Plot of sucrose concentration versus the measured average refractive index of the sample.
Fig. 9.
Fig. 9. (a) (358 kB) Video clip (not real time, 234 frames per video frame) of the bifocal gate scan in human thick stratum corneum in vivo. (Two frames are shown in the figure and the scale bars represent optical pathlength.). (b) Refractive-index tomogram calculated from (a).

Equations (8)

Equations on this page are rendered with MathJax. Learn more.

Δ l = f obj 2 f obj + f s ,
Δ l opt = n g { ( f obj a ) [ ( n 2 1 ) D 2 + 4 n 2 f obj 2 ] 1 2 2 f obj ( f a ) [ ( n 2 1 ) ( D ) 2 + 4 n 2 ( f ) 2 ] 1 2 2 f } ,
Δ l opt = n g { ( f obj a ) [ NA 2 ( n 2 1 ) + n 2 ] 1 2 ( f obj a Δ l ) [ NA 2 f obj 4 ( n 2 1 ) + ( nf Δ l ) 2 ] 1 2 f Δ l } .
Δ l opt n g n [ 1 + NA 2 ( 1 1 n 2 ) ] 1 2 Δ l .
Δ l opt n g n [ 1 + 1 2 NA 2 ( 1 1 n 2 ) ] Δ l .
x = 0 z 0 sin α [ n ( z ) ] 2 sin 2 α dz ,
dx df | z = z 0 = NA n ( z 0 ) [ n ( z 0 ) ] 2 NA 2 d z opt df | z = z 0 .
I ( l r ) 0 R ( l s ) h ( l s ) S ( Δ l i ) d l s ,
Select as filters


Select Topics Cancel
© Copyright 2024 | Optica Publishing Group. All Rights Reserved