Motivated by this link, I found that article to be enjoyable reading. There are several points that, in my opinion, are worthy of consideration.Wes wrote: ↑Thu Oct 10, 2019 10:42 pmSpeaking of illumination techniques I find relief phase contrast interesting
http://zeiss-campus.magnet.fsu.edu/refe ... 9-2007.pdf
Haven't yet had the patience to properly explore, maybe someone who has can chime in.
0. The method is essentially oblique illumination combined with PC.
1. The method can create different and richer, so to speak, images than conventional PC. The features of the results are summarized in Table 1 of the article. There are plus and minus points.
2. The method is seemingly very easy to implicate in ordinary PC microscopes, especially using a turret PC condenser (side note: Piper calls this condenser type a "Zernike phase contrast condenser"; perhaps, Prof Zernike influenced Zeiss to manufacture specifically turret PC condensers; Piper in his article used Leitz microscopes; whatever...). In the simplest way, rotate the turret to misallign the condenser annulus with the objective phase ring. Or combine an obliquely-located annular section with the condenser iris aperture to adjust the oblique PC illumination.
In my opinion, this method might be attractive to hobby microscopy, rather than to professionals. I suspect that relief PC images are not very appropriate for quantitative image analysis, at least because the background is not uniformly bright.
Two technical limitations that I see, for hobbyists who do not wish to fabricate specific opto-mechanical gadgets:
A - the relief PC needs much brighter light sources than ordinary PC (which, in turn, needs much brighter sources than brightfield).
B - some of the methods suggested by Piper are not easily feasible, because not all turret PC condensers have the iris aperture in series with a phase annulus. On my two different types of Zeiss PC condensers, for example, the iris aperture is installed in the BF, and the phase annuli see an empty opening (maximum aperture), which is fine for ordinary but not for relief PC.
So, Relief PC is added to my to do list.