Resolution-enhanced optical coherence tomography based on classical intensity interferometry

Abstract

We propose a fourth-order interference scheme for optical coherence tomography operating with broadband incoherent (or quasi-incoherent) light. It is shown that using this proposal, an axial resolution improvement by a factor of ͱ 2 and a better sensitivity for weakly reflecting samples are obtained than with the standard second-order correlation scheme. From a practical perspective, we suggest the use of broadband Q-switched pulses and performing ultrafast intensity correlation with a nonlinear crystal. The global performance of our proposal is illustrated by means of numerical simulations.

Intensity-interferometric spectral-domain optical coherence tomography with dispersion cancellation

“…Whereas a spectral-intensity OCT approach was recently put forward [26] as a counterpart to classical intensity-based TD-OCT [27], leading to an improvement in longitudinal definition, the method still lacks the dispersion cancellation property that is absolutely crucial for high-resolution imaging with broadband radiation. Inspired by recent endeavors on dispersion-cancellation interferometry [11], we show that the correlations between the random spectral intensity components in two interferometer arms at different frequencies play the key role in cancelling the dispersion in our SD-OCT configuration.…”

Resolution improvement in spectral-domain optical coherence tomography based on classical intensity correlations

“…This is exactly the same as the situation in the recently proposed TD-OCT setup based on classical intensity correlations [12,13]. Equation (7) implies that the field has a randomness specified by Gaussian statistics.…”

“…Similarly, the dispersion cancellation effect has been demonstrated also on the basis of a post-measurement spectral analysis of the interference fringes [11]. On the other hand, it has been shown that TD-OCT based on intensity correlations using classical broadband light provides a resolution enhancement by a factor of 2 p , though without the dispersion-cancellation effect [12,13]. It has also been shown that exploiting a nonlinear two-photon process as a detector in the conventional TD-OCT leads to an improvement of resolution, as well as sensitivity [14].…”

“…These results hold regardless of whether the broadband source generates stationary fields or partially or fully coherent pulses. Let us next consider SD-OCT based on classical intensity correlations, constructed in a similar way as the intensity-based TD-OCT system described in [12]. The intensities jU S j 2 and jU R j 2 of the fields from the sample and reference mirror are measured separately and their correlation is calculated.…”

Phase difference enhancement with classical intensity interferometry

“…It seems, however, that more recently the traditional form of intensity interferometry with classical light has received renewed attention in connection with stochastic electromagnetic fields [8][9][10][11][12] and, especially, in connection with classical counterparts of quantum imaging [13], namely, ghost imaging with classical light [14][15][16][17][18], ghost diffraction with classical light [19][20][21][22][23], and quantum-mimetic optical coherence tomography (OCT) [24][25][26].…”