Search found 58 matches

by ldflan
Sun Feb 28, 2021 10:43 am
Forum: Photography Through the Microscope
Topic: Inside a rosehip
Replies: 6
Views: 565

Re: Inside a rosehip

The hairs themselves are quite interesting, and seemingly have either a central channel or (as I think) they are folded around to form a kind of spiked tube, sort of like a blade of grass. The five-sided folicular organ at the base of the hairs and the structure of the hairs where they emerge from t...
by ldflan
Sat Feb 27, 2021 12:39 pm
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Re: Birefringence Terminology

DSC09400 RSZ.jpg R. blanda leaflet, 400x DIC 2020-12-03-13.28.47 ZS DMap (2) 1024.jpg R. blanda leaflet, 100x, Crossed polarizers and full wave retarder. Image stack of 11. And this is interesting: figures 3-4 show developing rosette type druse crystals. The authors don't note it, but at very early...
by ldflan
Sat Feb 27, 2021 9:02 am
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Re: Birefringence Terminology

Duke - "Animal or human tissue COM crystals are always polycrystaline. There're often definitely observed monocrystals in plant sections, but there are twinning crystals, polycrystaline particles are not uncommon as well." I am not sure it makes any difference, but di- and tri-hydrated forms of calc...
by ldflan
Fri Feb 26, 2021 12:02 pm
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Re: Birefringence Terminology

In this Javier's recent post you can see the oxalate crystals I was referring to, take a look at the linked full size image and you will see few one at extinction: https://www.photomacrography.net/forum/viewtopic.php?p=271475#p271475 Some of the twinned crystals do show a clear extinction point. Th...
by ldflan
Fri Feb 26, 2021 11:59 am
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Re: Birefringence Terminology

Optical activity can be demonstrated in solids as well as solutions. D and L rotary quartz, for example. Sure, although I think that this refers to different causes: organic molecules chirality is caused by the spatial asymmetry of their molecular structure while in quartz this is just impossible a...
by ldflan
Fri Feb 26, 2021 11:05 am
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Re: Birefringence Terminology

Thanks, Pau. Optical activity can be demonstrated in solids as well as solutions. D and L rotary quartz, for example. Here, maybe if the assembly of microcrystals that form a druse crystal are laid down by the responsible plastids in a helical pattern, we might have a similar polarity rotation effec...
by ldflan
Fri Feb 26, 2021 10:56 am
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Re: Birefringence Terminology

Duke - Thank you for the thoughtful reply and the images. Nucleation and crystallization processes for CaOx are probably very different in plants and animals, but it seems very clear that the biogenic CaOx crystals in plants incorporate macromolecules on some kind of net or sheath composed of protei...
by ldflan
Thu Feb 25, 2021 7:14 pm
Forum: Photography Through the Microscope
Topic: Birefringence Terminology
Replies: 11
Views: 210

Birefringence Terminology

I am trying to figure out the proper terminology to describe the optical qualities of Calcium Oxalate (druse) biocrystals ("CaOx") that occur in many type of angiosperms, in my case rose tissue. Many researchers describe biogenic CaOx crystals as being anisotropic and strongly birefringent, but this...
by ldflan
Mon Jun 22, 2020 4:43 pm
Forum: Equipment Discussions
Topic: Nikon Diaphot TMD w/ DIC -- Help!
Replies: 25
Views: 7791

Re: Nikon Diaphot TMD w/ DIC -- Help!

... My nosepiece (and I suspect all TMD nosepieces do, but maybe not) has an optic built into the "active" aperture. If only the fluorescence set-up scopes have this, then it might correct for the length increase. If all have this optic then I suspect Nikon has made this scope (with optics) to esse...
by ldflan
Sat Jun 20, 2020 11:47 am
Forum: Equipment Discussions
Topic: Nikon Diaphot TMD w/ DIC -- Help!
Replies: 25
Views: 7791

Idflan, for multiband fluorescence, the excitation of the all the desired bands needs to be simultaneous, so you'd need multiple LEDs in very close proximity, or an optical solution for combining more widely separated lamps into a single beam, perhaps with an offset reflecting parabola fed by sever...
by ldflan
Sat Jun 20, 2020 8:09 am
Forum: Equipment Discussions
Topic: Nikon Diaphot TMD w/ DIC -- Help!
Replies: 25
Views: 7791

Critcally was the use of a small plastic fresnel lens in front of the excitation filter, and the LED mounted at focal distance (a cm or so) in front of the cube (fresnel). No collimators or lamphouses necessary. René - Thanks. Pretty sure I can visualize what you are describing. There should be roo...
by ldflan
Sat Jun 20, 2020 8:01 am
Forum: Equipment Discussions
Topic: Nikon Diaphot TMD w/ DIC -- Help!
Replies: 25
Views: 7791

LEDs as fluorescence excitation source is a real alternative both in expensive off the self devices and DIY systems It's what many amateurs use, including myself https://www.photomacrography.net/forum/viewtopic.php?p=201937#201937 (now improved with some modifications) The main idea is simple: put ...
by ldflan
Sat Jun 20, 2020 7:48 am
Forum: Equipment Discussions
Topic: Nikon Diaphot TMD w/ DIC -- Help!
Replies: 25
Views: 7791

"...the easier way to spot it is the loss of parfocality between the objectives." This is very good to know! Thank you! I will look for that. "...some kind of TL compensating system [may be] present, likely a very weak negative lens or a different lens than in the original model and this could not b...
by ldflan
Wed Jun 17, 2020 2:47 pm
Forum: Equipment Exchange
Topic: WTB: Nikon CF N Plan 10x /0.30 DIC and 40x/ 0.70 DIC 160/.17
Replies: 0
Views: 1459

WTB: Nikon CF N Plan 10x /0.30 DIC and 40x/ 0.70 DIC 160/.17

Thought I would see if anyone has one of either to spare... Thanks! Leonard
by ldflan
Tue Jun 16, 2020 11:51 am
Forum: Equipment Discussions
Topic: Nikon Diaphot TMD w/ DIC -- Help!
Replies: 25
Views: 7791

I hope you put a UV barrier filter somewhere in the tube before the eyepieces!

Leonard