An interferometer apparatus for providing quadrature detection in Fourier Domain Optical Coherence Tomography comprising: a first arrangement (100, 105, 115, 400, 405) comprising a source arrangement and a splitter, the splitter configured to split a radiation from the source arrangement into a first electro-magnetic radiation provided to a biological sample and a second electro-magnetic radiation provided to a reference, wherein the source arrangement is intentionally configured to cause the spectrum of at least one of the first and second electro-magnetic radiations to change over time; and a combiner second arrangement (401, 415, 410, 420) configured to combine solely a first polarization component of a third electro-magnetic radiation provided simultaneously from multiple depths of the biological sample by transmission or reflection of the first electro-magnetic radiation with solely a second polarization component of a fourth electro-magnetic radiation provided by transmission or reflection of the second electro-magnetic radiation by the reference, means to specifically control the first and second polarization components to be at least approximately orthogonal to one another, and a detection third arrangement (120, 425, 430, 435, 440, 445, 450, 455) configured to generate at least a first and second interference signal from the combined components of the third and fourth electro-magnetic radiation and to control a difference in phases of the first and second interference signal to exclude nπ, where n is an integer and greater than or equal to 0. a first arrangement (100, 105, 115, 400, 405) comprising a source arrangement and a splitter, the splitter configured to split a radiation from the source arrangement into a first electro-magnetic radiation provided to a biological sample and a second electro-magnetic radiation provided to a reference, wherein the source arrangement is intentionally configured to cause the spectrum of at least one of the first and second electro-magnetic radiations to change over time; and a combiner second arrangement (401, 415, 410, 420) configured to combine solely a first polarization component of a third electro-magnetic radiation provided simultaneously from multiple depths of the biological sample by transmission or reflection of the first electro-magnetic radiation with solely a second polarization component of a fourth electro-magnetic radiation provided by transmission or reflection of the second electro-magnetic radiation by the reference, means to specifically control the first and second polarization components to be at least approximately orthogonal to one another, and a detection third arrangement (120, 425, 430, 435, 440, 445, 450, 455) configured to generate at least a first and second interference signal from the combined components of the third and fourth electro-magnetic radiation and to control a difference in phases of the first and second interference signal to exclude nπ, where n is an integer and greater than or equal to 0. a combiner second arrangement (401, 415, 410, 420) configured to combine solely a first polarization component of a third electro-magnetic radiation provided simultaneously from multiple depths of the biological sample by transmission or reflection of the first electro-magnetic radiation with solely a second polarization component of a fourth electro-magnetic radiation provided by transmission or reflection of the second electro-magnetic radiation by the reference, means to specifically control the first and second polarization components to be at least approximately orthogonal to one another, and a detection third arrangement (120, 425, 430, 435, 440, 445, 450, 455) configured to generate at least a first and second interference signal from the combined components of the third and fourth electro-magnetic radiation and to control a difference in phases of the first and second interference signal to exclude nπ, where n is an integer and greater than or equal to 0.