Optical Coherence Tomography

Optical Coherence Tomography (OCT) is an imaging technique that provides high resolution, non-destructive, in situ, real-time reflectivity profiling of non-absorptive samples. Medical applications include noninvasive ophthalmological imaging and endoscopic gastrointestinal tract imaging.

Luna offers a variety of standard products for OCT systems, as well as the capability to build customized products or subsystems for particular applications.

Fiber-based OCT systems require precise polarization management, accurate delay control, fast wavelength tuning, and complete optical system integration capabilities.

Typical solutions include:

• Polarization Control: In order to produce a good interferometric signal, the state of polarization (SOP) of the two interfering arms should be aligned. Luna offers manual and dynamic polarization controllers with minimal integration effort and low loss. For polarization-sensitive OCT, a more sophisticated polarization control after the light source is needed to launch specific polarization states. Luna supplies deterministic polarization state generators with up to 6 distinctive SOPs.
• Optical Delay Control: Optical path matching is mandatory to produce perfect interference patterns. Luna offers multiple manual and motorized delay lines with high speed, high accuracy, high repeatability and reliability performance. For more fine tuning of phase, Luna has fiber optic based phase shifters to do active phase locking.
• Detectors: Luna supplies high-speed balanced photonics detectors (BPD) with low noise and small package size. For polarization-sensitive OCT, a more sophisticated polarization-sensitive balanced detector is offered.
• K-Clock: For swept-source OCT, a high-speed linear detuning laser source is required. At a fixed sweep rate, different beat frequencies correspond to different delays or reflections from different depths in the sample. Distance accuracy is highly dependent on how linear the laser tuning profile is. In practice, most lasers don’t have an ideal linear profile. Luna supplies K-clocks based on free space Mach–Zehnder interferometer.
• Optical subassembly module: Luna has the capability and expertise to integrate various elements of an OCT system into subassemblies optimized to the requirements of different applications.