Abstract
An optical coherence tomography (OCT) system with a 2.8-mm beam diameter is presented. Sensorless defocus correction can be performed with a Badal optometer and astigmatism correction with a liquid crystal device. OCT B-scans were used in an image-based optimization algorithm for aberration correction. Defocus can be corrected from ? 4.3 ?? D to + 4.3 ?? D and vertical and oblique astigmatism from ? 2.5 ?? D to + 2.5 ?? D . A contrast gain of 6.9 times was measured after aberration correction. In comparison with a 1.3-mm beam diameter OCT system, this concept achieved a 3.7-dB gain in dynamic range on a model retina. Both systems were used to image the retina of a human subject. As the correction of the liquid crystal device can take more than 60 s, the subject’s spectacle prescription was adopted instead. This resulted in a 2.5 times smaller speckle size compared with the standard OCT system. The liquid crystal device for astigmatism correction does not need a high-voltage amplifier and can be operated at 5 V. The correction device is small ( 9 ?? mm × 30 ?? mm × 38 ?? mm ) and can easily be implemented in existing designs for OCT.
Highlights
Optical coherence tomography (OCT) is a noninvasive, highresolution optical imaging technique that is based on low coherence interferometry, and it is highly useful for generating crosssectional images of turbid media
Our system is less complex than a traditional Adaptive optics (AO)-OCT design, and due to the small size of the liquid crystal (LC) device (9 mm × 30 mm × 38 mm), the concept can be implemented in commercial systems to achieve diffraction-limited resolution imaging
We presented an OCT system with a 2.8-mm beam diameter and a Badal optometer for defocus correction and an LC for vertical and oblique astigmatism correction
Summary
Optical coherence tomography (OCT) is a noninvasive, highresolution optical imaging technique that is based on low coherence interferometry, and it is highly useful for generating crosssectional images of turbid media. The ANSI safety rules for safe use of lasers limit the amount of light that can be sent into the eye.[4] Another option to improve image quality is to increase the photon collection efficiency of the sample arm. This can be achieved by using a larger beam size than the ∼1.2-mm beam diameter that is used in the sample arm of standard OCT instruments. Merits of a larger beam size are a decreased speckle size and improved lateral resolution, which is limited by the diffraction limit set by the beam size, the focal length of the eye, and the wavelength of the light
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