The spectral resolution provided by the GEMINI Interferometer is not constant as a function of wavelengths, but it increases at longer wavelengths. This behavior is due to both the Fourier Transformation approach and the birefringence, which depends on the wavelength.
Please refer to the following graph:
The graph above shows the best spectral resolution achievable by the two standard versions of the GEMINI Interferometer. However, the GEMINI offers the ability for customers to adjust the spectral resolution simply via software: the user can even decide to perform faster measurement with poorer spectral resolution. A change in the spectral resolution does not affect the throughput of the device.