Sea Urchin Spines SEM

Images made through a microscope. All subject types.

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houstontx
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Sea Urchin Spines SEM

Post by houstontx »

Sea Urchin Spines found in tidal pool sediment. Very small probably about 0.25-0.5mm across and 3-4mm long
Attachments
Sea Urchin Spine2 SMALL.jpg
Sea Urchin Spine1SMALL.jpg

Sumguy01
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Re: Sea Urchin Spines SEM

Post by Sumguy01 »

=D> Very interesting.
Thanks for sharing

houstontx
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Re: Sea Urchin Spines SEM

Post by houstontx »

Thanks! I realize now I should clarify: top photo shows the spines as found, the 2nd pic is a spine cross section ( seen out of focus in top left of first pic)

rjlittlefield
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Re: Sea Urchin Spines SEM

Post by rjlittlefield »

Very nice!

I'm curious, what sort of preparation did these have to go through, in order to be imaged?

--Rik

houstontx
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Re: Sea Urchin Spines SEM

Post by houstontx »

Hi Rik these were dehydrated in ethanol, dried further with supercritical CO2 (critical point drying) and sputter coated with a Gold/Palladium alloy.

They were the typical purple and white urchin color before sample prep. Still trying to figure out how to add the color back in...

Pau
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Re: Sea Urchin Spines SEM

Post by Pau »

Very nice image, I love SEM (and have no access to one of them)
They were the typical purple and white urchin color before sample prep. Still trying to figure out how to add the color back in...
I would try the following approach (just a not proven idea):
after setting up the sample but before metal sputtering you can take an optical focus stacked image with white light to get a lower resolution image with the natural colors, then after coating you can search with the SEM the same framing and take the image to lately merge both images in PS or similar software
Pau

houstontx
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Re: Sea Urchin Spines SEM

Post by houstontx »

Pau,

Good idea, it would be tricky yes but layering or using just the color channel over the sem image could work, no idea how to do it. Not good at photoshop or similar, but I'm realizing its something I need to learn.

rjlittlefield
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Re: Sea Urchin Spines SEM

Post by rjlittlefield »

Thanks for the detail about preparation.

About the colors, I have seen Pau's approach used a few times.

Doing it fully automatically is indeed tricky because you have to match perspective -- not just viewing angle but also distance from center of perspective to the subject. This requires a careful match between structure of the scanning electron scope and choice of optical lens.

More practical, though less elegant, is to let the viewpoint be slightly wrong, then use human smarts to paint colors on the SEM image, using colors picked from the optical image. Think of it as being just like the old-fashioned "tinting" process used to augment B/W photography, but using exactly the right colors instead of closest match from a palette of stains.

--Rik

Smokedaddy
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Re: Sea Urchin Spines SEM

Post by Smokedaddy »

Very nice Chris. Wish we were neighbors. 8)

iconoclastica
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Re: Sea Urchin Spines SEM

Post by iconoclastica »

Here's an example of a test photo, that was shot on 9x12cm large format black and white negative film. I had a Canon 400D piggybacked on top of the technical camera with the bw-film, to shoot the same digitally. After scanning the negative I added the colour from the digital image. The result is both hi-res and coloured (and dusty):
scanned negative
scanned negative
+
digital shot
digital shot
=
scanned negative with added colour (note the right side where the digital image fell short!)
scanned negative with added colour (note the right side where the digital image fell short!)
The perspective was not exactly the same. By clicking the visibility of either layer in photoshop I even see the little ape nodding:
misalignment
misalignment
This approach works, nonetheless, since there's very little information in the color layer that adds to (or detoriates) the sharpness of the photo. In the combined photo above you can see the error at the edge of the top-left ear and along the upper edge of the colour target print.
digital image, no luminosity, only colours
digital image, no luminosity, only colours
procedure
  • shoot both photos, more or less aligned
  • load them as layers in photoshop, BW below and colour on top
  • select both layers
  • menu: edit|autoalign layers
  • set the blending mode of the digital layer to "color"
--- felix filicis ---

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