Several issues for talk about.
First, I have the raw files of the pics, so, with time I will upload all the coloured images of them; they are mainly monochromatic grey images, but in some cases, there are some artifacts in small tiny points; If you change the position of the slit or the prism position you obtain different mono-colours as in DIC.
Yes Apochronaut, sorry, I´m not native English, and not very fluent with it (I never pass the different English subjects in my studies
) ; so, when I write, I can be wrong with things; I didn’t take attention about the denomination of slit Pluta system: Interference contrast microscopy was confused by me with Differential Interference Contrast; Zeiss Plas DIC is similar in concept (Could be that I´m wrong in this, and it would be good to know, as I will discuss later) despite that the polarizer filter in PZO /Pluta system is below the specimen, and in Zeiss is over the specimen; Could be that all this different systems have slight different names due to patent rights?I haven´t got the Pluta´s books from which is taken the diagram that I included posts ago, neither the manual of operation for PZO ICM (Interference Contrast Microscopy; lets use this acronym despite DIC) or slit condenser; If somebody has got, please share with us.
At this point, from Pluta information I can´t deduce the slit width in his proposal; So I try to deduce it by the next ways: a) the Zeiss paper of PlasDic (here, the relevant issue of the similarity of PZO ICM and PlasDIC, are they similar?) it´s say that must be close of 0.25 p.u. of the distance between the interference fringe distance in a conoscopyc view, b) Studying the PZO slit condenser, it´s clear that the slit must be adjustable between tenths of mm (lets say 0,3mm to few millimetres), c) Test & error taking as start point the a & b clues.
In a conoscopyc view when I get the ¿ICM?, ¿slit DIC?, ¿other thing without name until now?, I see the diagonal (45º ) black interference fringe, that is about ¼ to 1/6 of the slit width, the slit width is about 1/3 to ¼ of the distance between the black interference fringe, and the first coloured fringe; so, without the slit mask, you see the nice pattern of the central dark fringe and one or two coloured at each side, and with the slit mask, you only see the dark one. At this point, we must return to the Plata illustration, in c) is draw a conoscopyc view with several fringes!!!, is it possible to get it with a slit mask? for me no! with a wider slit that I use, you will see in a conoscopic view the original prism pattern, and no effect in orthoscopyc view.
With a smallest slit, using 0,5 mm slit with the 40X objective 0,65NA despite the 4mm slit, I can isolate the central part of the central dark fringe, with a dark, without fringes conoscopyc view, and a dark orthoscopyc view… and that doesn´t match neither with the picture of a condenser slit in Figure 5 in Zeiss paper, neither with the ability of PZO condenser to get slits below 0.3-0.2 mm, neither with the extremal loss of light that is involved in that extreme thin slits… so I deduce that the proper adjust of the slit is that, that I´ve described first, than match with the Zeiss paper, and so the conoscopyc view in C) of the Pluta´s diagram must be without slit…
Said that, I have test that if you adjust the dark fringe in the centre of the slit in the conoscopyc view, you have a low contrast orthoscopyc image; you need to bias the dark fringe to one of the sides of the slit; more bias, more contrast, and more density gradient; the density gradient depends too on the width of the slit. So, there is a lateral component of the illumination. In Zeiss paper you can see too an arrange with lateral asymmetry in figure 3.
What have I got? ICM Pluta illumination technique?, nothing related with it but a more expensive oblique illumination?... I think that ICM, but with my limited experience and knowledge, and no more documents about it availed, I´m not sure.
Has ICM Pluta illumination any lateral gradient? I don´t know too. Could be that the prisms used for ICM b PZO and Plas DIC by Zeiss have the shear angle and other desing oriented to reduce the gradient?. The PZO upper unit for ICM is complex, and must permit to change the position of the prism in various ways.
Sure Squisalot, yes, the last image isn´t with the slit in the condenser, it is with a PZO condenser prism in my homemade condenser; it is was only the results of the first fast test that I have done with that configuration, and it seems like slightly mismatched DIC as Scarodactyl says. It needs time, because as I have read, you can adjust the match of the prisms in several ways, one of them moving the prism over or under the back focal plane of the condenser, that´s the reason for how it´s made my condenser: I can adjust the vertical position of the condenser mask or support of the prism.
Scarodactyl, for the oblique pics I used the sliding mask that I have posted, I can adjust “on line” the cardboard sandwiched between the two aluminium frames; I´m happy with the results, cheap and fast way to create different mask (I have to tried with coloured ones) and easy adjustment. The idea from Saul for access in two orthogonal axis I have to try.
There is the remaining question about If I try to adjust the Z position of the condenser for get a focus image of the slide and the field iris, the upper lens of the condenser touches the slide with the aplanat and achromat SK optics. I don´t know if I´m wrong in the diagnosis about this issue; I think that the reason is that the field lens focal points and distances between field iris, field lens, and condenser in the Optiphot line is different than in the SK line, and the Abbe SK condenser tolerates these differences but the SK aplan and achro not; Can Apochronaut or somebody confirm this?.
Zzffnn speaks about oiling the condenser; I did so with the yesterday attempt with the broken CF 100X 1,25, but not with the below NA objectives, could be that the reason for the need of touch of the upper part of the aplanat and achromat condenser with the slide with the CF 40X 0.65?, I think that no, but… relevant, because I would like to use the aplanat or achromat SK optics, but in this point I have to use the Abbe one.
Thank all
Jose Antonio
