National Instruments Corporation

Kalyanramu Vemishetty

Kunal H Patel

Adam C Ullrich

Stephen A Hanssen

A signal processing system implemented on a Field Programmable Gate Array (FPGA) operates according to a low frequency K-Clock to sample Optical Coherence Topography (OCT) signals, as opposed to relying on a high frequency K-Clock to obtain the same information. A resampler is used to resample the OCT signal uniformly in the optical frequency domain. The resampling may be performed by extracting instantaneous phase information from a low-frequency digitized K-Clock signal, unwrapping the extracted phase information, multiplying the unwrapped extracted phase information with an interpolation factor to obtain recalculated phase information, determining one or more integer crossing points corresponding to the recalculated phase information, and interpolating one or more values of the OCT signal based on the one or more integer crossing points. The integer crossing points may represent points in phase divisible by 360 degrees, within the range of points in phase defined by the recalculated phase information.

Real-time resampling of optical coherence tomography signals using a field programmable gate array

A system may include a plurality of subsystems, e.g. instrumentation units housed in separate chassis, each chassis including multiple instrumentation devices, e.g. data acquisition cards. Each subsystem may generate a local reference clock, which may be phase aligned and locked with respect to one or more similar reference clocks of other subsystems, via a high-level precision time protocol (PTP). Each instrumentation device within a given subsystem may generate its own sample clock based on the local reference clock, and may generate its own trigger clock based on its own sample clock. All trigger clocks may be synchronized with respect to each other through a future time event issued using the PTP, and each instrumentation device may then use its trigger clock to synchronize any received trigger pulses, which may also be issued through future time events using the PTP. This results in synchronizing the received triggers across all participating instrumentation devices across all participating subsystems, ensuring that data acquisition is properly synchronized across the multiple subsystems.

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Austin, TX, United States of America

Kalyanramu Vemishetty