Microscopy 101
being mounted on a standard stub and is therefore capable of the full range of stage tilt and rotation. When an ideal black background is required, the pin-and-
pedestal approach for preparation of small samples is a viable alternative to the Pohl specimen holder. While entirely feasible as demonstrated in this paper, mounting of microfossils may be daunting to execute and requires the utmost patience and fine motor function. In general use, the pin-and-pedestal technique may be most practical for the mounting of structures >100μm, provided enough carbon adhesive is applied to the pin tip. In the realm of micropaleontology, these include a wide range of microfossils of common interest such as conodont elements, foraminiferal tests, and radiolarian skeletons.
References [1] VV Nabokov, Pale Fire: A Novel, G. P. Putnam’s Sons, New York, 1962. ISBN 9780399121616.
[2] JE Whittaker and RL Hodgkinson, J Micropalaeontol 9 (1991)
https://doi.org/10.1144/jm.9.2.219.
[3] H Pohl, Microsc Res Tech 73 (2010)
https://doi.org/10.1002/ jemt.20835.
[4] SMS McLachlan et al., Rev Palaeobot Palynol 292 (2021)
https://doi.org/10.1016/j.revpalbo.2021.104452.
[5] V Pospelova et al., Marine Micropaleontol 75 (2010)
https://doi.org/10.1016/j.marmicro.2010.02.003.
[6] KN Mertens et al., Rev Palaeobot Palynol 184 (2012)
https://doi.org/10.1016/j.revpalbo.2012.06.012.
[7] AM Price et al., Rev Palaeobot Palynol 226 (2016) https://
doi.org/10.1016/j.revpalbo.2015.12.009.
Figure 4: Scanning electron photomicrograph of a Cannosphaeropsis franciscana dinoflagellate cyst specimen with original and digitally replaced backgrounds.
on an aluminum stub surface; (B) same image with post-production Adobe Photoshop removal of the background replaced with black infill.
Discussion Pohl’s method, albeit more sophisticated in design than the
pin-and-pedestal mount, requires a milled pot cavity backdrop, platform, and screw pin mount. Equivalent image quality is achieved with Pohl’s apparatus, but it is more cumbersome in its application and requires the manufacture and assembly of multiple parts (see Figure 1 in [3]). In addition, Pohl’s specimen holder was designed for the purpose of imaging arthropod specimens (see Figure 2 in [3]) that are orders of magnitude larger than the dinoflagellate cysts examined in this study. Pohl’s holder also requires that samples be adhered to a pin with nail polish that would result in smaller structures, such as most microfossils, being engulfed by the medium. Additionally, Pohl’s pin-and-pot configuration requires the specimen to be fixed at one viewing angle at a time. Tis requires that the sample be removed from the SEM when any stage adjustment is required, whereas the pin-and-pedestal mount benefits from
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