Systems Technology Group designs Optical Delay Line for OCT

The G&H Systems Technology Group (STG) together with the engineering team at G&H Torquay has designed a motorized optical delay line (see illustration) for optical coherence tomography (OCT) applications, with the first samples due to be shipped in October.

G&H has sold components and sub-systems into the OCT market since 2000. OCT is an optical imaging technique, not dissimilar to ultrasound and most commonly used for ophthalmic applications. OCT offers significantly higher image resolution than ultrasound, typically in the region of 5-10μm. By comparison, the resolution of ultrasound is typically millimeters.

OCT is an interferometric technique, exploiting the fact that light waves will be preferentially reflected from different layers of material (e.g. organic tissue), and the reflected waves will interfere to provide amplitude maxima and minima at a sensitive detector. By scanning a light source across the area of interest, a 3D image can be generated. OCT is particularly useful in imaging formerly inaccessible areas of tissue such as the layers of the retina and there has been an explosion of growth in ophthalmic applications since 2000. The technique is now widely used for the early diagnosis of conditions such as macular degeneration and glaucoma, two of the main causes of blindness.

In all commercial OCT systems, the interferometer at the heart of the instrument is based on fiber optics, and since low optical losses are critical for good imaging performance, G&H fused fiber couplers have become the component of choice for many OCT customers. Building upon its component business, G&H has successfully moved up the food chain to supply “build-to-print” optical sub-systems, including interferometers and spectrometers.

G&H established the STG in early 2013 to offer customers a complete engineering design service of which the OCT delay line is the first example. Provided with a basic optical and mechanical outline requirement, the STG has selected the optical components and provided the full mechanical design for the module. The optical delay line plays a critical role in the OCT instrument, allowing the interferometer path length to be scanned through the coherence point, enabling the image to be formed. Key requirements of the design are repeatability and accuracy of the scan distance throughout the lifetime of the instrument.

For further details on G&H’s OCT technology please view the relevant pages, these include couplers, module and systems and general expertise in this area. Please contact the STG in Torquay on +44 1803 407807 or click here.

This is the first of what is intended to be many instances of successful collaboration between the STG and G&H’s engineering teams fulfil the increasing needs and expectations of its customers.