The effects of reduced bit depth on optical coherence tomography phase data

Area of Science:

• Optical Engineering
• Biomedical Imaging
• Metrology

Background:

• Previous research indicated minimal impact of digitizer bit depth on optical coherence tomography (OCT) magnitude data quality.
• Studies often concluded 8-bit resolution was sufficient, comparable to 14-bit systems for magnitude imaging.
• The effect of bit depth on phase data accuracy remained largely unassessed in prior work.

Purpose of the Study:

• To investigate and elucidate the differential effects of digitizer bit depth on OCT magnitude versus phase data.
• To highlight the critical importance of bit depth for phase-resolved OCT applications.
• To inform the design considerations for future phase-resolved OCT systems.

Main Methods:

• Experimental analysis of OCT data acquired at varying digitizer bit depths.
• Comparative assessment of phase and magnitude data accuracy as a function of bit depth.
• Theoretical considerations of signal processing in OCT systems.

Main Results:

• Demonstrated significant divergence in the impact of bit depth on OCT phase and magnitude data.
• Revealed that lower bit depths can critically compromise phase data accuracy.
• Quantified the trade-off between digitizer bit depth and speed for phase-sensitive OCT.

Conclusions:

• Digitizer bit depth has a disproportionately large effect on phase data accuracy compared to magnitude data in OCT.
• Optimizing bit depth is essential for accurate phase-resolved OCT measurements, including motion and birefringence.
• Design choices in OCT systems must carefully balance bit depth requirements with digitizer speed limitations.