Design of a Linear Wavenumber Spectrometer for Line Scanning Optical Coherence Tomography with 50 mm Focal Length...

Area of Science:

• Optical Engineering
• Biomedical Imaging
• Spectroscopy

Background:

• Optical coherence tomography (OCT) is vital for bioimaging and non-destructive testing.
• Wider bandwidth light sources enhance OCT resolution but introduce spectral nonlinearity in spectral domain OCT (SD-OCT).
• Spectral nonlinearity degrades spectrometer signal sensitivity, impacting depth-dependent measurements.

Purpose of the Study:

• To design and optimize a novel spectrometer for SD-OCT to mitigate spectral nonlinearity.
• To improve the signal-to-noise ratio (SR) and robustness of OCT systems.
• To investigate a Grism-based spectrometer for enhanced performance.

Main Methods:

• Design optimization of a spectrometer using a cylindrical mirror (radius 50 mm), a broadband light source (830 ± 100 nm), and a grating (1600 lines/mm) using MATLAB and ZEMAX.
• Development and analysis of a Grism-based spectrometer.
• Evaluation of nonlinearity error and sensitivity to optical angles.

Main Results:

• The proposed cylindrical mirror-based design reduced nonlinearity error from 157°× μm to 10.75°× μm.
• The initial design showed high sensitivity of the SR ratio to imaging optics' angles.
• The Grism-based spectrometer achieved an optimized SR ratio of 0.97 with a nonlinearity of 0.792°× μm (Δθ/Δk).

Conclusions:

• The Grism-based spectrometer offers a robust solution for reducing spectral nonlinearity in SD-OCT.
• This design enhances measurement accuracy and signal sensitivity for OCT applications.
• The Grism-based approach provides superior performance compared to previous designs.