Abstract
We demonstrate high resolution, three-dimensional OCT imaging with a high speed, frequency swept 1300 nm laser source. A new external cavity semiconductor laser design, optimized for application to swept source OCT, is discussed. The design of the laser enables adjustment of an internal spectral filter to change the filter bandwidth and provides a robust bulk optics design. The laser generates ~30 mW instantaneous peak power at an effective 16 kHz sweep rate with a tuning range of ~133 nm full width. In frequency domain reflectometry and OCT applications, 109 dB sensitivity and ~10 microm axial resolution in tissue can be achieved with the swept laser. The high imaging speeds enable three-dimensional OCT imaging, including zone focusing or C-mode imaging and image fusion to acquire large depth of field data sets with high resolution. In addition, three-dimensional OCT data provides coherence gated en face images similar to optical coherence microscopy (OCM) and also enables the generation of images similar to confocal microscopy by summing signals in the axial direction. High speed, three-dimensional OCT imaging can provide comprehensive data which combines the advantages of optical coherence tomography and microscopy in a single system.
Highlights
Optical Coherence Tomography (OCT) [1] has found widespread applications for cross sectional imaging of tissue in situ with micron scale resolution
In this study we demonstrate a compact, frequency swept light source at 1300 nm for high speed, three-dimensional, swept source OCT imaging
Similar to optical coherence microscopy (OCM) images, where depth gating is provided by the coherence gate, can be generated from the three-dimensional data sets
Summary
Optical Coherence Tomography (OCT) [1] has found widespread applications for cross sectional imaging of tissue in situ with micron scale resolution. Time domain OCT imaging using two-dimensional zone focusing and image fusion or focus tracking to increase the depth of view has been demonstrated, but suffers from slow data acquisition speeds.[3, 38,39,40,41] The high data acquisition speed of swept source OCT makes it possible to acquire images with enhanced depth of field in a fraction of a second by C-mode imaging, fusing together multiple images with different focal depths, as demonstrated in twodimensional, time domain OCT.[3] Full, three-dimensional data sets with enhanced depth of field can be acquired within several seconds by acquiring and fusing multiple threedimensional data sets with different focus depths This overcomes depth of field limitations which are normally associated with the small focused spot sizes required for high transverse resolution. Similar methods for generating en face images have been used to produce OCT fundus images in ophthalmic OCT.[7, 49, 50] These results demonstrate that high speed, three-dimensional OCT combines the functions of optical coherence tomography and microscopy in a single instrument
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