Patent ID: 6850325

Claim:
An apparatus for the determination of a condition or state of an object based on quasi-elastic interaction between the object and light transmitted to the object, comprising: a diffractive optical element being adapted to be illuminated by a incoming light beam, the diffractive optical element comprising a diffracting region defining a diffraction plane, the incoming light beam forming an angle of incidence to a normal of the diffraction plane, the diffracting region comprising a first diffracting structure for diffraction and focussing of a first light beam to the object, and a second diffracting structure that is laterally displaced relative to the first diffracting structure for diffraction and focussing of a second light beam to the object, the first and the second light beam being diffracted at a first diffraction angle to a normal of the diffraction plane, the first and second diffracting structures focussing the first and second light beams in the same focussing plane, said focussing plane being substantially perpendicular to propagation directions of the first and second light beams, the diffracting region further comprising a receiving diffracting structure for diffraction of light from the light beams that has interacted with the object, the diffracted light being diffracted in a second diffraction angle to the normal of the diffraction plane, wherein the size of the angle of incidence of the incoming light beam and the second diffraction angle are substantially equal.