Absolute linear-in-k spectrometer designs enabled by freeform optics

term, respectively. A simulation model was developed to evaluate the performance of SD-OCT with the designed spectrometers. Without the k-interpolation in software, results show that the two freeform spectrometers achieve a roll-off gain of 5.24 dB over the imaging depth from 0.5 to 5.5 mm, while the maximum imaging depth is 5.8 mm. Finally, a 4.2-µm-FWHM axial PSF was maintained throughout the imaging depth in air.