Microscopy 101
optical system. Due to the optical limitations of the micro- scope, increasing the number of pixels or decreasing their size does not necessarily provide higher resolution with, for example, a “high-resolution” camera often better suited to a low-magnification system such as a stereomicroscope, whereas a “low-resolution” camera with larger pixels is often better suited to a high-magnification compound microscope system where high dynamic range and high sensitivity may be required. Te overall dynamic range, that is, the ability to discrimi-
Figure 3: An up-close image revealing the fracture and propagation of a crack in a thin polymeric film under tension on Linkam’s MFS tensile device, with mea- surements carried out using LINK extended measurements software module. Image © Linkam 2019.
single quantitative value. Pixel size and pitch of the cam- era should be matched to the resolution of the microscope, which is governed by the numerical aperture (NA) of the
nate between dark and light areas of an image, is also a key parameter to consider. Tis can be affected by pixel size, so while having small pixels may improve resolution, this gener- ally decreases the dynamic range. Tis is especially important in material science applications where observations of small changes in color are oſten a key measurement parameter. Cam- eras are generally limited to 8 bits per color in an RGB image, so it is important to ensure the camera can fill the full 8 bits in each channel. Frame rate determines the smoothness of operation in
live-view imaging. While higher frame rates produce smoother transitions, matching frame rate to the demands of the intended application is important, as is understanding the consequences of certain choices. For example, dimensionally larger images typically result in slower frame rates, while high frame rates can quickly produce extremely large and unwieldly image data sets.
Integrated Dynamic Data and Image Acquisition Solutions Linkam offers several integrated
stage and image capture modules that are optimized for different applications. Teir high-performance image capture module includes a new 3.2 Mp camera with a 4:3 aspect ratio that is an ideal fit for micro- scope imaging. Te new camera provides an integrated imaging solution when combined with Linkam’s LINK soſtware package and image capture module to enable image capture, synchronized with temperature control of a sample and cor- related with other controlled and mea- sured parameters. LINK system control and image
capture soſtware supports a number of modules to optimize image-based sample characterization, making it
extremely
Figure 4: Pathway from microscope view to captured image, demonstrating how (ii) the eye piece or C-mount contribute to vignetting and (iii) the camera sensor FOV should be positioned for optimal imaging of the region of interest (ROI).
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easy to automatically capture images at specified points during an experiment. Input triggers are stored and marked on a chart for easy synchronization with other equipment, and each image is stamped with the current temperature and other measured parameters so offline analysis is straightforward. In addition, the LINK Extended Measurements module enables precise
www.microscopy-today.com • 2020 November
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