I expected the high magnification images to be the most difficult for this system to achieve with uniform high resolution and even illumination. My initial tests of the scanning system were with a 45 degree inclined flat target covered with a patch of mm graph paper and 5X magnification for the bellows lens set at f/4 for an intended 50X final magnification with an NA of 0.1. This target would reveal uneven illumination as well as variation in the resolution of the matted paper fibers. The graph paper was oriented so that one set of lines was parallel to the stage and facing one of the slit sources. A circle was drawn at the center of the target with a graphite pencil and the system aligned with the slit and camera lens both focused on the horizontal graph line passing through the circle. Figure 13 shows the very narrow scan line for this condition.  The stage was manually raised and lowered for Figures 14 and 15. The scan line, indicated between arrows, greatly broadens near the edges of the field along the axis of the slit illumination lens so that it falls just within the high resolution portion of the depth of field. The system was covered with a light-proof cloth tent for the scanning light image of this target shown in Figure 16. Note that the illumination and paper fiber resolution are uniform across the entire field.  The graphite coated circle becomes an ellipse with the graphite coating giving rise to specular reflection of the scanning light beam. This test needs to be repeated with recording on 35 mm film. The edges of the field in the direction of the short axis of the ellipse (highest and lowest portions of the field) would be expected to be blurred by the further broadening of the illuminating beam thickness with the field width 1.5 times wider on the film image.

click image to enlarge (115K) Figure 13	click image to enlarge (101K) Figure 14
click image to enlarge (94K) Figure 15	click image to enlarge (297K) Figure 16

The fly head was photographed with the digital camera using broad area lighting from the side in addition to the stationary ring of light from the two opposed slit light sources for the image in Figure 17. This was done for comparison with a scanning light image of the same field of view shown in Figure 18. Comparison of these images demonstrates that the scanning method does not faithfully record the black hair patterns. Another problem with the scanning image is the lack of clues to judge depth of the features because the images are isometric projections and lack out-of-focus regions. This missing information is evident in the low magnification side view of the fly head shown in Figure 19. This conventional photomacrograph was recorded with the Nikon Coolpix lens at maximum magnification and broad area lighting. Engineering drawings typically contain front, top, and end views of a subject to aid in three dimensional visualization. Jim Gerakaris showed that the best way of obtaining the missing depth perception is to record stereo pairs with the scanning light method. 

click image to enlarge (107K) Figure 17	click image to enlarge (230K) Figure 18
Figure 19

This article is the first progress report for my now functional scanning light photomacrography system. A large capacity eucentric stage has been built so that stereo pairs can be easily recorded. This stage was described in my article Eucentric Stage for Recording Stereo Pair Photomicrographs, originally publshed in the September 2005 issue of Microscopy Today. My original calculations of the field size limitations of the scanning light method need to be revised now that I know that the NA of the illumination beam must be significantly greater than anticipated. The theoretical field size limits need to be verified by experiments using 35 mm film recording covering a wide range in magnification. These results can be the subjects for future articles.