Patent ID: 8665446

Claim:
An apparatus for coherent multi-dimensional optical spectroscopy, comprising an optical assembly, wherein the optical assembly comprises: means for splitting a base light pulse into at least a first light pulse, a second light pulse, a third light pulse and a fourth light pulse, where the first light pulse, the second light pulse and the third light pulse are suitable for interacting with a sample such as to generate an at least third order signal, focusing optics for focusing the first light pulse, the second light pulse, the third light pulse and the fourth light pulse at a site on the sample, and delay means adapted for varying respective arrival times of the first light pulse, the second light pulse, the third light pulse and the fourth light pulse at the sample site relative to each other, detection means for detecting an interference signal of the at least third order signal and the fourth pulse, wherein: the means for splitting the base light pulse include non-diffractive optics, the optical assembly is configured such that the light pulses between entrance of the base light pulse into the optical assembly and the focusing optics are at least for part of their optical paths guided pairwise in such a manner that changes in an optical path length due to a vibration of the means for splitting the base light pulse or due to an intentional variation using the delay means are, at least to a first order, identical for pulses of each pair, and the pulse pairs are chosen such that effects that the change in the arrival times of the pulses of each pair, due to a change in the optical path length have on the phase of the interference signal, at least partly compensate each other.