Optical Coherence Tomography System Design
Optical coherence tomography creates depth-resolved information by measuring interference from backscattered light. The practical instrument combines source spectrum, interferometer, sample optics, scanning, detection, signal processing, calibration, safety, and motion management.
Define the imaging problem
The requirements should identify tissue or material, imaging depth, lateral and axial resolution, field, acquisition time, working distance, probe geometry, wavelength band, and acceptable exposure. These choices influence the source, detector, optics, scanning method, and processing load.
Architecture choices
Time-domain, spectral-domain, and swept-source approaches create different trades in speed, sensitivity, ranging depth, calibration, and component availability. The sample arm and reference arm need compatible polarization and dispersion behavior. Fiber components simplify routing but introduce polarization, connector, and back-reflection considerations.
Axial resolution is related to source spectrum, while lateral resolution and depth of focus depend on sample-arm numerical aperture. Increasing one form of resolution may reduce usable depth or alignment tolerance, so the full imaging task should drive optimization.
Scanning and optomechanics
Galvanometers, MEMS scanners, rotating probes, or translated samples require different relay and packaging strategies. Scan-induced aberration, telecentricity, pupil placement, distortion, and synchronization affect the reconstructed volume. Mechanical design must protect alignment while supporting cleaning, service, and any disposable interface.
Calibration and verification
Testing can include axial and lateral point-spread response, sensitivity roll-off, depth calibration, scan linearity, field distortion, artifact mapping, polarization and dispersion sensitivity, thermal drift, and repeatability. Phantoms and reference targets should be selected for the intended application and used with controlled acquisition settings.
OCT for a medical product also requires risk management, usability, software, electrical safety, and regulatory evidence. Optical engineering should provide traceable requirements and test results that integrate with those broader activities.
PAO supports optical design for medical devices and custom optical design for complex clinical instruments.