HIGH RESOLUTION MICROGRAPHS OF DIATOMS

Until recent days making high resolution micrographs of diatoms was a laborious science. Because of the low contrast special sensitive material had to be used and special methods of developing had to be applied. Very often micrographs were insufficient because of the limited depth of field of the objectives and even good micrographs could never display the entire frustule in focus. Today digital cameras in combination with digital image processing have changed the scene completely: You simply make some 5 photoes moving the stage by 1 um, afterwards you select the best image.

1 Biddulphia
.
2 Triceratium 3 Stictodiscus 4 Aulacodiscus 5 Campylodiscus
6 Surirella
.
7 Surirella 8 Surirella 9 Surirella 10 Didymosphenia
11 Epithemia
.
12 Navicula 13 Pinnularia 14 Pinnularia 15 Pinnularia
16 Stictodiscus
.
17 18 Arachnoidiscus 19 Arachnoidiscus 20

Horizontal width: 20x5: 270 um    40x5: 170 um    100x5: 65 um

A great advantage are special programs, like HELICON-FOCUS, which is available as share ware. You simply make 10 or 20 single images, moving the stage by 1 um per image, then load this pack of images into the programme and start the processing procedure. HELICON-FOCUS extracts the sharp parts of the images and assembles them to a new image, adding every part in an "intelligent way" to the image just assembled. This procedure requires images with overlapping sharp parts, so the stage must be moved by only 1 um per image. The assembling can be tracked on the screen, as every step needs about one second. So artefacts or ruptures can be detected. In such a case some images must be erased and the whole process must be started again. The proramme can be handled easily, all features are self-explaining.

1 Biddulphia
.
2 Biddulphia 3 Biddulphia 4 Kittonia 5 Biddulphia
6 Campylodiscus
.
7 Campylodiscus 8 Campylodiscus 9 Campylodiscus 10 Campylodiscus
11 Surirella
.
12 Trinacria 13 Trinacria 14 Stictodiscus 15 Stictodiscus
16 Triceratium
.
17 Triceratium 18 Triceratium 19 Trinacria 20 Trinacria
21
.
22 Triceratium 23 Gyrodiscus 24 Auliscus 25 Auliscus
26 Actinoptychus
.
27 Actinoptyhus 28 Aulacodiscus 29 Aulacodiscus 30 Aulacodiscus
31 Aulacodiscus
.
32 Aulacodiscus 33 Aulacodiscus 34 Coscinodiscus 35 Coscinodiscus
36 Arachnoidiscus
.
37 Arachnoidiscus 38 Arachnoidiscus 39 Arachnoidiscus 40 Arachnoidiscus
41 Actinocyclus
.
42 43 44 45 Ardissonia
46 Ardissonia
.
47 Ardissonia 48 Mastogloia 49 Mastogloia 50 Mastogloia
51 Navicula spectabilis
52 Diploneis 53 Navicula 54 Stauroneis 55 Trachyneis
56 Navicula
.
57 Navicula 58 Navicula 59 Navicula 60 Stauroneis
61 Gyrosigma
.
62 Pleurosigma 63 Stauroneis 64 Didymosphenia 65 Didymosphenia

All images on display were taken with a simple digital camera (KODAK EasyShare C613, 6,1 megapixel). The pictures have 2848x2134 pixel corresponding to jpgs of about 0.8 MB. Light source: Low voltage bulb plus interference filter "green". The images have been sampled down to 850x637 pixel.

SEM-Images of diatoms

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