Piracetam crystals

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 4:49 am

I've been using a plastic analyser for a while and finally managed to find a decent one. Here is a shopped picture of some new filters with shots of piracetam crystals inside them. 100 times magnified

arturoag75 · Post by **arturoag75** » Thu Jul 07, 2011 7:19 am

WOW!!
original shot and nice color

!
Arturo

Cactusdave · Post by **Cactusdave** » Thu Jul 07, 2011 7:50 am

Clever idea and good execution, though if I was being 'picky' I think I would have arranged the filters on a different background. I'm not sure that background really compliments them. BTW they are Zeiss neutral density filters aren't they? I think I've got a similar set somewhere.

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 7:52 am

Thanks, Arturo! There is a very noticeable difference between my old DIY filter from the LCD screen of a tetris game and the new one.

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 8:03 am

Cactusdave wrote:Clever idea and good execution, though if I was being 'picky' I think I would have arranged the filters on a different background. I'm not sure that background really compliments them. BTW they are Zeiss neutral density filters aren't they? I think I've got a similar set somewhere.

I think they are neutral density filters. I've never used such before but the one that has a value of 0,03 dims the light to a much higher extent than the 0,5 one.

This is the reflection of my camera lens from the surface of the 0,03 filter.

And the actual filters. Both of them are zeiss, not sure about the third one.

The other filter transmits green light and reflects purple-ish colours (lower wavelenghts I suppose but I might be wrong)

As for the background I grabbed the closest textbook with a dark cover:

I had no intention of producing the image I posted so didn't really care about the background. I agree, I would've used a different one, not sure exactly what though

Cactusdave · Post by **Cactusdave** » Thu Jul 07, 2011 9:24 am

An interesting and amusing choice of background.

Lecturer, practitioner or both? My background was in cell biology and cancer research before retirement. I think the third filter would be a green interference filter, at least it is in the similar set I have.

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 9:51 am

Cactusdave wrote:An interesting and amusing choice of background. Lecturer, practitioner or both?

None. I am still a student.

Cactusdave wrote:I think the third filter would be a green interference filter, at least it is in the similar set I have.

What is this set good for? I told a friend about a problem with the light intensity so he gave me this set of two 0.5 and one 0.03 neutral density filters plus the green one. He didn't really say what the original purpose of the set is.

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 10:53 am

Perhaps this might give you a better idea of the green filter. I used a CD as a reflective diffraction grid to generate an incandescent bulb spectrum. The top image is (-)filter and the bottom one is (+)filter.

Then I used the filter box as a holder and situated my desk lamp on the right side of the image. You can see the reflection on the right and whats transmitted to the left.

Any information about the nature of this filter set and its applications are highly appreciated.

Cactusdave · Post by **Cactusdave** » Thu Jul 07, 2011 10:54 am

Good question. The neutral density filters were probably useful to help with exposure control in pre-digital photography days, while maintaining a fixed colour temperature. The green filter was probably used to increase contrast for photographing certain histology stains. There seem to be quite a lot of these sets around so I guess they were supplied as a standard accessory with Zeiss microscopes at a certain time.

Edit: BTW I love your innovative experiments with the filter.

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 11:00 am

Thanks, Cactusdave! This makes sense since my friend works at a histopathology lab and said they wont be needing these anymore.

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 12:46 pm

This thread went a bit off-topic

so here are some actual shots of piracetam crystals. This chemical is somewhat difficult to use for that purpose since it easily forms clumps that are of no use in polarisation microscopy. I found out that spreading piracetam solution to a very large surface helps to make crystals of the appropriate size.

rjlittlefield · Post by **rjlittlefield** » Thu Jul 07, 2011 2:16 pm

bromodomain wrote:This thread went a bit off-topic

Going off-topic is an honored tradition at photomacrography.net.

One of my own threads started off talking about a simple way to draw scale bars but got diverted into the physics of diffraction. Oddly, the diversion ended up being among the most productive discussions I ever had! Anyway, if you are bothered by diversion, please just nudge people back in line or suggest that they start a new thread. We'll figure out after a while what your preferences are.

By the way, while I'm off-topic myself, I'll mention that the standard posting limits call for no more than 6 images per day in each image gallery. (The technical discussion forums are unlimited.) No need to modify anything you've done so far, but please keep the limits in mind for future postings.

Thanks!

And now back to piracetam crystals...

--Rik

bromodomain · Post by **bromodomain** » Thu Jul 07, 2011 2:44 pm

I love going off-topic for the simple reason that I learn new things (as in this case). I just felt that people would probably like to see the crystals. I wasn't aware of the 6 images per day rule but I'll keep it in mind for future reference.

Therefore feel free to go off-topic.

Speaking of physics I'm still not sure how the psychedelic imagery in polarisation microscopy is generated. I know about the function of the polariser and analyser and that the colour is a function of thickness but when is the actual colour generated?

BTW I noticed that the green filter changed its transmission properties when tilted relative to the light source.

rjlittlefield · Post by **rjlittlefield** » Thu Jul 07, 2011 3:22 pm

bromodomain wrote:but when is the actual colour generated?

The crystals rotate the axis of polarization differently for each wavelength of light. Strong colors occur when for some wavelengths the axis of polarization ends up crossed with the analyzer so that wavelength gets extinguished, while others are not and make it through.

BTW I noticed that the green filter changed its transmission properties when tilted relative to the light source.

Definitely consistent with being an interference filter.

--Rik

bromodomain · Post by **bromodomain** » Fri Jul 08, 2011 12:07 am

Thanks for the explanation! If I use light of a certain wavelength am I going to see light intensity differences instead of colour differences?