Low-Aberration High-Speed-Compatible Optical Delay Line

We describe a simple approach to dispersion-free optical delay line design that provides very low aberration over an extended delay range. In this approach we minimize aberrations by directing non-axial beam displacements along a line of symmetry built into the apparatus. We show improved performance and significant reduction of wavefront aberrations by comparing simulation and experimental results with a similar delay line that lacks this line of symmetry. The new design facilitates transform-limited recovery of spectral resolution in Fourier transform coherent anti-Stokes Raman scattering, and accordingly we demonstrate 3.5 $cm^-1$ spectral resolution with a 10 ps delay scan range.