One embodiment of an apparatus in accordance With the
present invention is shoWn in FIG. 1 by Way of illustration
and not limitation. Apparatus 10 comprises light source 12
and beam expander 14, Which is disposed adjacent to light
source 12 and betWeen light source 12 and diffractive
element 16. In the embodiment of FIG. 1 diffractive element
16 is a disk having a plurality of openings (see FIG. 2).
Apparatus 10 further comprises holder 20, Which holds substrate slide 22, Which comprises a number of features 24
on surface 23 of slide 22. Objective lens 26 lies between
substrate slide 22 and detector 28 and includes emission
?lter 27, Which blocks excitation light scattered by the
substrate. Emission ?lter 27 may be an interference ?lter
(multi-layer dielectric). For a high numerical aperture sys
tem With near 1:1 optics, the ?lter is usually positioned
betWeen tWo symmetrically placed identical (or nearly so)
high-NA lenses. Alternatively, the ?lter may be positioned
betWeen the lens and the array detector if the distance is
longer than the distance from the lens to the substrate.
Emission ?lter 27 may be an emission ?lter Wheel such as
depicted in FIG. 3. Diffractive element 16 is driven by motor
30. The operation of apparatus 10 is controlled by a micro
processor device (not shoWn), Which also comprises a data
acquisition system.