If only glass is placed between the polarizer and analyzer, the crystal will not show artificial colors (try it in a 9-well Pyrex depression plate). The artificial colors come from the diffraction of visible light from the plastic ware, which depending upon the type of plastic and the way the plate is manufactured, will have some preferred orientation of the polymer chains. Although it could have more to do with the method of manufacture of the plate.
I would love to hear a different explanation from someone that either sells or manufactures crystallization plastic ware. Diana ****************************** Diana R. Tomchick Department of Biophysics, Rm. ND10.214A University of Texas Southwestern Medical Center 5323 Harry Hines Blvd. Dallas, TX 75061 USA 214-645-6383 (office) On Aug 16, 2020, at 12:19 PM, Nukri Sanishvili <sannu...@gmail.com> wrote: EXTERNAL MAIL Hi All, Adding some more details to what's been said already. Only because I've seen too many times the polarizers being used incorrectly. First, you need two polarization filters which are typically called polarizer and analyzer. First one (the polarizer) lets through only the light waves of a certain polarization. Then one needs to rotate the other one (analyzer) until there is no more light getting through. At this point the analyzer blocks the light that was let through by the polarizer This is what Diane referred to as 90 degrees. Please note that the polarizer-analyzer plates stay parallel to each other. After that, a crystal is placed between them and is rotated. Unless it is a crystal with cubic symmetry, at some angles it will light up in beautiful colors and at some angles it will not. This is because the crystal changes the polarization of the light passing through and "90 degree setup" of the polarizer/analyzer pair is no longer valid for newly polarized light. Please note that using plastic plates in this context is not quite appropriate. The plastic polymer itself changes the polarization as well and therefore it breaks the main principle of this method. With plastic interference, it will be impossible to reach complete darkening of the field of view. I can almost hear a lot of people saying that they've used it with plastic plates without a problem. I believe it to be the case but it still doesn't make it right. Best, Nukri On Sun, Aug 16, 2020 at 9:15 AM Matthias Zeug <matthias.z...@gmx.de<mailto:matthias.z...@gmx.de>> wrote: Hi all, The polarizer-microscope in our facility is not working properly, and I have to check my plates using a standard stereo-microscope. As a workaround, I thought about buying one at Amazon, placing it on top of the plates and rotating it to still test for birefringence. The product is linked below. Does anyone have some experience with this kind of "homemade" system? And also (this might be a stupid question), does the product even work? As far as I know, the polarizers in the microscopes are linear polarizers, whereas the product linked below is a circular polarizer. I would also be happy for product recommendations (optimally available at the German Amazon). Cheers Matthias https://www.amazon.de/dp/B00XNMXYBY/ref=cm_sw_r_cp_apa_i_5YsoFbFQXTBP9 ___________________ Buchmann Institute of Molecular Life Sciences Goethe University Frankfurt ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 ________________________________ To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 CAUTION: This email originated from outside UTSW. Please be cautious of links or attachments, and validate the sender's email address before replying. ________________________________ UT Southwestern Medical Center The future of medicine, today. ######################################################################## To unsubscribe from the CCP4BB list, click the following link: https://www.jiscmail.ac.uk/cgi-bin/WA-JISC.exe?SUBED1=CCP4BB&A=1 This message was issued to members of www.jiscmail.ac.uk/CCP4BB, a mailing list hosted by www.jiscmail.ac.uk, terms & conditions are available at https://www.jiscmail.ac.uk/policyandsecurity/
