An optical coherence tomography apparatus including a sample arm and a reference arm, the apparatus comprising: at least one first wavelength swept laser arrangement (95, 100, 100', 250, 301) providing at least one first electro-magnetic radiation to a sample (86, 136, 328) via the sample arm and at least one second electro-magnetic radiation to a reference (82, 124, 316) via the reference arm, wherein the at least one first wavelength swept laser arrangement includes an optical resonator, a gain medium and a wavelength tunable filter which comprises a reflector to produce a rapidly-swept multiple-frequency-mode output; wherein the reflector is adapted to be controlled to cause a mean frequency of a spectrum of at least one of the first electro-magnetic radiation or the second electro-magnetic radiations to change substantially continuously over time at a tuning speed that is greater than 100 Tera Hertz per millisecond; and at least one second arrangement comprising a multi-element array detector configured for: (i) detecting an interference between (a) at least one third radiation received from the sample (86, 136, 328) via the sample arm and associated with the at least one first radiation and (b) at least one fourth radiation received from the reference (82, 124, 316) via the reference arm and associated with the at least one second radiation, each element of the multi-element array detector detecting a different wavelength fraction of the interference (ii) obtaining a complex cross spectral density from a Fourier transform of said detected interference in the time domain, and (iii) converting the complex cross spectral density to a depth profile in a tissue by performing a Fourier transform of the complex cross spectral density. at least one first wavelength swept laser arrangement (95, 100, 100', 250, 301) providing at least one first electro-magnetic radiation to a sample (86, 136, 328) via the sample arm and at least one second electro-magnetic radiation to a reference (82, 124, 316) via the reference arm, wherein the at least one first wavelength swept laser arrangement includes an optical resonator, a gain medium and a wavelength tunable filter which comprises a reflector to produce a rapidly-swept multiple-frequency-mode output; wherein the reflector is adapted to be controlled to cause a mean frequency of a spectrum of at least one of the first electro-magnetic radiation or the second electro-magnetic radiations to change substantially continuously over time at a tuning speed that is greater than 100 Tera Hertz per millisecond; and at least one second arrangement comprising a multi-element array detector configured for: (i) detecting an interference between (a) at least one third radiation received from the sample (86, 136, 328) via the sample arm and associated with the at least one first radiation and (b) at least one fourth radiation received from the reference (82, 124, 316) via the reference arm and associated with the at least one second radiation, each element of the multi-element array detector detecting a different wavelength fraction of the interference (ii) obtaining a complex cross spectral density from a Fourier transform of said detected interference in the time domain, and (iii) converting the complex cross spectral density to a depth profile in a tissue by performing a Fourier transform of the complex cross spectral density.