Kazuro Yamada

Three-beam spectral-domain optical coherence tomography for retinal imaging

Abstract. A three-beam spectral domain optical coherence tomography system (OCT) whose center wavelength is 840 nm was developed. The three beams focus on fundus 3.1 mm apart from each other and are detected by a single line sensor. The distance between the beams is fixed and the beams scan a total area of 10×10  mm2 while keeping this separation during three-dimensional (3-D) measurement. The line rate of the sensor is 70 kHz, therefore the total speed is equivalent to 210k A-scans per second in this system. A 1000(x)×500(z)×250(y) voxel volumetric 3D OCT data set can be acquired within 2 s. Images of a model eye, a healthy human eye and a diseased eye taken by this system are shown and evaluated. The image quality of one B-Scan is as good as an image from a single-beam OCT. Adjustment among the beams is solved by additional signal processing using a model eye. A multi-beam OCT has the potential not only for high speed imaging but also functional imaging although problems such as compensation among the beams and motion artifacts must be solved.

In-vivo retinal imaging by multi-beam spectral-domain optical coherence tomography with a novel spectrometer design

We have developed a multi-beam spectral-domain optical coherence tomography system with a single line sensor for human retina imaging. Three beams are used and the scan area is a 10-mm square on the fundus. These three beams focus on the fundus at locations 3.1 mm apart from each other to satisfy the ANSI safety standards. The line rate is 70k A-scans/s for each beam, equivalent to a total line rate of 210k A-scans/s for the three beams. The spectrometer has a single line sensor for the three beams, which leads to differences among the three beams such as pixel resolution, roll-off characteristic, and sensitivity. The 3D image is acquired by piecing the images together while calibrating the depth resolution and compensating the roll-off characteristics of each beam. We obtained an image of a healthy human retina.