Abstract
Purpose :
Galvanometer scanner response fundamentally limits optical coherence tomography (OCT) imaging performance. Scanning nonlinearities distort anatomic features and reduce image quality/resolution; and underdamped impulse response increases mirror settling duration and total acquisition time. Here, we present hardware and software scanner response optimizations and demonstrate benefits for video-rate volumetric intraoperative OCT.
Methods :
Scanners (Saturn 5B, ScannerMax) were optimized iteratively using servo tuning parameters. A Gaussian process regression (GPR) model of step responses was developed and used to identify optimal tunings (Fig. 1). Improved imaging performance was validated using a custom 400 kHz swept-source OCT system and custom volumetric scan waveforms (Fig. 2).
Results :
Mirror settling time was reduced by 39-58% and 17-58% for the slow- and fast-axis mirrors, respectively, over default tunings (Fig. 1(d),(e)). OCT volumes were acquired of 25G forceps at 16 Hz volume rate with 2560x250x50 pix. and 250 return lines (Fig. 2(a),(c)-(f)) and at 20 Hz volume rate with 2560x400x50 pix. and 0 return lines (Fig. 2(b),(g)-(j)). Scanner tuning optimization increased the number of linearly sampled lines by 12-101% (Fig. 2(f) vs. Fig. 2(c)-(e)) and by 18-72% (Fig. 2(j) vs. Fig. 2(g)-(i)) over default tunings for each scan waveform. Removing return lines increased the number of linearly sampled lines by 33-64% for all tunings (Fig. 2(g)-(j) vs. Fig. 2(c)-(f)).
Conclusions :
The combination of hardware and software optimizations significantly increased both volume acquisition speed and linear field-of-view of volumetric OCT. These optimizations can benefit intraoperative OCT by improving the response of the scanners and minimizing image distortions during video-rate volumetric imaging of surgical dynamics.
This is a 2021 ARVO Annual Meeting abstract.