Stage-scanned chromatically aberrant confocal microscope for 3-D surface imaging

摘要

A method for full-field surface profiling in the tandem scanning confocal microscope has been previously described. The technique utilizes chromatic aberration to produce an extended and color coded focal volume. Planes at different axial depths within this volume correspond to the foci of different wavelengths through the intentionally aberrant system. To determine the height of any point within the field, the confocal detection system must be capable of identifying the wavelength of the most intensely reflected light from that point. Hence the relative sensitivity of the detector and the spectral response of the imaging system are important parameters. We have utilized xenon and mercury arc sources and compared results with various types of objective lens. One potential limitation of this microscope is the fact that the introduction of longitudinal chromatic aberration affects the correction of the optics for plan imaging, i.e., introduces spherical aberrations, but the technique is rapid and produces results well correlated with more conventional techniques. To allow detailed study of the use of a chromatic 3-D probe for surface imaging we have designed and constructed a stage-scanned instrument which uses on-axis optics and is therefore free from spherical aberrations and can be corrected optimally. The instrument is described and results presented for single pass 3-D imaging.