Patent ID: 8395780

Claim:
An optical assembly for use in coherent two- or more-dimensional optical spectroscopy, comprising a cross-grating configured to simultaneously split a base pulse into at least a first, a second, a third and a fourth light pulse, delay means for varying the arrival times of said first through fourth light pulses at a sample location with respect to each other, said delay means being adapted to independently adjust a time delay between the first and second light pulses and a time delay between the second and third light pulses, wherein said delay means comprise stationary and moveable reflectors arranged such as to reflect said first to fourth light pulses pairwisely, wherein said pairs of pulses are chosen such that the effects a common delay of the pulses of a pair has on the phase of an interference signal between a third order signal generated by interaction of three of the light pulses with a sample, and a remaining light pulse at least partially compensate each other, a first reflector arranged to receive the first to fourth light pulses emerging from said cross-grating and reflect the same in parallel to each other, and a second reflector arranged to receive said first to fourth light pulses after having passed the delay means and focus the same at said sample location, wherein at least one of the first and second reflectors is an off-axis parabolic mirror or a reflective microscope objective comprising a convex spherical mirror and a concave spherical mirror opposing each other.