Ultrahigh-resolution, high-speed, Fourier domain optical coherence tomography and methods for dispersion compensation

Abstract

Ultrahigh-resolution optical coherence tomography uses broadband light sources to achieve axial image resolutions on the few micron scale. Fourier domain detection methods enable more than an order of magnitude increase in imaging speed and sensitivity, thus overcoming the sensitivity limitations inherent in ultrahigh-resolution OCT using standard time domain detection. Fourier domain methods also provide direct access to the spectrum of the optical signal. This enables automatic numerical dispersion compensation, a key factor in achieving ultrahigh image resolutions. We present ultrahigh-resolution, high-speed Fourier domain OCT imaging with an axial resolution of 2.1 ìm in tissue and 16,000 axial scans per second at 1024 pixels per axial scan. Ultrahigh-resolution spectral domain OCT is shown to provide a ~100x increase in imaging speed when compared to ultrahigh-resolution time domain OCT. In vivo imaging of the human retina is demonstrated. We also present a general technique for automatic numerical dispersion compensation, which is applicable to spectral domain as well as swept source embodiments of Fourier domain OCT.

Optical coherence tomography imaging in uveitis

“…In 2002, a third generation time-domain (TD) OCT 3 (Stratus OCT; Carl Zeiss Meditec) became available with an axial resolution of 10 lm and a scan velocity of 400 axial scans/sec. Since 2004, higher resolution spectral-domain OCT (SD OCT) has entered clinical practice with reported resolutions of 3-5 lm as well as improved visualization of retinal morphologic and pathologic features [7][8][9][10][11][12][13][14]. SD OCT is the current gold standard for posterior segment retinal tomography.…”

“…It may use either a superluminescent diode or femtosecond titaniumsapphire laser as a light source. In contrast to TD OCT, the reference mirror for SD OCT remains stationary, and the depth information is acquired by analyzing the interference patterns in a spectrum of mixed reflected lights [7][8][9][10][11][12][13][14]. SD OCT technology uses low-coherence interferometry to detect light echoes, relying on a spectrometer and high-speed camera and based on the mathematical premise of Fourier transformation.…”

Artefact reduction for cell migration visualization using spectral domain optical coherence tomography

“…(a) background measured by blocking the sample arm, cf. Table 1(b) [9]. TVFP noise is not suppressed as indicated by white arrow.…”

“…Optical coherence microscopy (OCM) using en face TD detection offers the benefit of coherence gating [1,8]. Acquisition speed and sensitivity was increased by using spectral domain (SD) OCT [9] and with numerical techniques transversal resolution could be retained outside focus region [10,11]. One of the limits of 3D deconvolution is that it tends to reduce the sensitivity by the introduction of noise [11] and because of the required high phase stability it could not be applied to in vivo imaging [10].…”

“…With spectral domain OCT the signal Sðw; xÞ detected by the spectrometer depending on optical frequency w and transversal position x can be expressed as [9,21] Sðw; xÞ ¼S Sðw; xÞ þ S Sðw; xÞ þ Nðw; xÞ þ WðwÞ þW Wðw; xÞ ð 1Þ whereS Sðw; xÞ is the interference spectrum required for tomogram generation, S Sðw; xÞ represents interferometric autocorrelation terms, Nðw; xÞ is stochastic measurement noise (e.g. thermal and shot noise), WðwÞ is fixed-pattern noise of the camera, and W Wðw; xÞ is time-varying 1 fixed-pattern (TVFP) noise.…”