An optical imaging apparatus (100) for examination of an object of interest (101), the optical imaging apparatus (100) comprising an optical radiation source (102) adapted to emit a primary optical radiation beam onto the object of interest (101), an optical radiation detector (106) adapted to detect a secondary optical radiation beam emitted by the object of interest (101) upon absorbing the primary optical radiation beam, a magnetic field generating element (107) adapted to generate an inhomogeneous magnetic field varying along an extension of the object of interest (101), and a determination unit (108) adapted to determine information concerning the object of interest (101) based on an analysis of the detected secondary optical radiation beam in combination with an analysis of the inhomogeneous magnetic field.