Compared with competing swept source (SS) designs in the 1050-nm spectral range, short cavity lasers offer higher sweep speeds and narrower instantaneous linewidths. The commercial short cavity swept laser described in this paper operates at a 100-kHz swept rate and allows imaging over a 4-mm-depth range with 6-dB roll off in air and 5.3-µm axial resolution in tissue. It is therefore not surprising that, as mentioned by the authors, several companies are now developing short cavity swept lasers for the OCT market.
The main advantages of SS/Fd detection presented in this paper over spectral/Fd-OCT were already known. Nevertheless, with application of this novel light source they are clearly visible. These include lower sensitivity roll off, longer imaging range, higher detection efficiencies, and reduced A/D depth range. The biggest advantage of SS/Fd-OCT over spectral/Fd-OCT is its potential for fabricating very compact all-fiber SS/Fd-OCT instruments without the need for bulky optical elements. This could, in the near future, result in the development of systems with scale factors several times smaller than current spectral/Fd instruments.
Besides introducing this novel light source, the authors evaluate several acquisition schemes and data processing and manipulation steps, giving a complete overview of the state-of-the-art trends in retinal and anterior segment imaging in the 1050-nm spectral range. This includes demonstration of sensitivity roll off for different OCT technologies, comparison of OCT retinal image quality for different acquisition speeds, sampling densities, and frame averaging. Additionally, several volume acquisition raster patterns are evaluated, including medium and large equidistant sampled volumes, and dual-spot/dual-interferometer acquisition. An impressive image of the cone photoreceptor mosaic is presented, proving that standard lateral resolution OCT with ultrahigh acquisition speed is effective in visualizing parafoveal cone photoreceptors in healthy subjects. Examples of high-quality anterior segments acquired with the same system promises to improve performance for instrumentation that images both the retina and the anterior eye.
In summary, repeating after authors: All these advantages suggest that SS OCT at 1050-nm wavelengths will play an important role in future ophthalmic instrumentation.
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