1. An optical imaging apparatus for obtaining depth profile information from a transparent object, comprising: a spectral optical coherence tomography (OCT) apparatus for generating a sample beam for transversely scanning said object; a spectrometer for producing spectral OCT data from light returned from said object along at least one line extending in a longitudinal direction; a confocal detector for producing an en-face image of the object in a transverse plane from said sample beam; a processing unit generating from said spectral data OCT image data along said at least one line; said processing unit being configured to display said en-face image; a selection device for selecting a portion of said en-face image; and said processing unit being configured to display said portion of said OCT image data corresponding to said portion of said en-face image.