Mosquito Larva with Polarised Light

Cactusdave · Post by **Cactusdave** » Sat Jan 05, 2013 7:45 am

Inspired by several beautiful posts of live mosquito larvae showing detail of the internal musculature with polarised light, I thought I would see what I could do with killed and mounted specimens now that the cold weather has killed off the live material. Now I’m no expert at mounting so I tend to look to those who have more skill and patience for my material. Last Summer I bought a number of nice slides of various arthropods (ticks, water mites, fleas etc.) from Lawrence Bircham in the USA who advertises his slides from time to time on Ebay. We had some correspondence and he made at my suggestion some mounts of mosquito larvae without harsh alkaline clearing treatment that destroys muscle, and without pressure during mounting. These slides proved to have very good preservation of the muscle structure of the larvae and provided some interesting photo opportunities with polarised light and various retarders. Here are some of the results of my efforts.

This first image is a stitch of 72 pictures taken using a Zeiss Neofluar X6.3 objective on my Nikon Diaphot with polarised light and a retarder. Total magnification at camera about X15.75. A larger version is here http://photosynth.net/view.aspx?cid=f53 ... ab58642de3 I found imaging the whole larva satisfactorily a challenge, but at least with some permanent mounts, it’s one I can return to. I found that a ‘head’ or ‘head and shoulders’ portrait was more satisfactory as slightly higher magnification could be used successfully, it was easier to get even illumination across the specimen, and stacking was a practicable addition to the mix.

This image is a stack and stitch of 91 images taken using a Zeiss X20 UD achromat objective. This objective was designed by Zeiss for use with their Federov universal stage and has a long working distance and is strain free. Used with an extender on the Diaphot to allow it to reach focus, the effective measured magnification is closer to X15, so with the X2.5 factor from the microscope this gives a total magnification of about X37.5. A larger 50MP version is here http://photosynth.net/edit.aspx?cid=919 ... 320f346bbe and shows plenty of detail when zoomed into. Lighting was polarised light plus a home made retarder made from two layers of Sellotape on a clean glass slide.

This version was made using a Nikon X10 Plan DIC objective with polarised light and a quartz wedge. It is a stitch of 31 images with Microsoft ICE. A larger version is here http://photosynth.net/view.aspx?cid=94e ... 7623f12308

I made these pictures some months ago, but recently returned to the slide using a Wild Fluotar X10 0.45 objective. This high NA objective is of outstanding quality and gives excellent images on the Nikon Diaphot. It is a short objective and requires an extender to reach focus. I also removed the upper fixed polarising filter from the Diaphot and replaced it with a home made rotatable filter so that partial polarisation could be achieved.

This image was stitched from 43 pictures using partially crossed polars. Total magnification at camera about X25. A larger 40MP version is here. http://photosynth.net/view.aspx?cid=ccf ... 3ae07bd76c

The final image used the same Wild objective and is a stitch of 33 images using partially crossed polars and a ¼ wave retarder. A 44MP version is here http://photosynth.net/view.aspx?cid=51b ... e8024632a7

pwnell · Post by **pwnell** » Sat Jan 05, 2013 12:39 pm

Last one is especially great.

Jacek · Post by **Jacek** » Sat Jan 05, 2013 12:58 pm

The last two beautiful

Cactusdave · Post by **Cactusdave** » Sat Jan 05, 2013 2:13 pm

Thanks guys. The two shots with the Wild X10 fluotar are my favourites as well. It's a great little lens and worth looking out for if you have a 160mm 'scope. I saw one on a US surplus site for $80 recently. A steal at that price.

Cactusdave · Post by **Cactusdave** » Sat Jan 05, 2013 2:31 pm

I also took a look at the larva's breathing tube. Wild X10 Fluotar 0.45 polarised light with X10 DIC prism and retarder in the light path. Stitch of 8 images.

A larger version of 28MP is here. http://photosynth.net/view.aspx?cid=3d8 ... 8614d79895 The rings strengthening the tracheae can clearly be seen when zooming into the larger linked image. Interesting to compare with Charles' beautiful 'in vivo' pictures here http://www.photomacrography1.net/forum/ ... php?t=2059 and here http://www.photomacrography.net/forum/v ... thing+tube These may be oldies, but they are definitely goldies !

Charles Krebs · Post by **Charles Krebs** » Sat Jan 05, 2013 9:19 pm

Very nice!

Maybe I'm an old stick-in-the-mud, but I'm most partial to the last two with the neutral colored backgrounds.

curt0909 · Post by **curt0909** » Sat Jan 05, 2013 10:42 pm

Great subject in pol. Well done Dave.

Cactusdave · Post by **Cactusdave** » Sun Jan 06, 2013 1:52 am

Thanks Charles and Curt.

Charles -- I agree. I prefer the more subdued backgrounds to the wilder shores of psychodelia that polarised light and retarders can produce. I begin to think we are in the minority though, when I look at the winners of recent photomicrography contests.

Perhaps it's just a question of current fashion

I hope you noticed my links to your earlier wonderful images of the mosquito larva breathing tube in living subjects. There must be so many gems like those buried in the forum archives.