Focus helps us see things clearly, both as scientists looking through a microscope and as individuals. This piece examines the connection between focus in both microscopy and in our lives.
Electron Microscopy – Focus
Collecting an image that conveys microscopic structures clearly, accurately, and efficiently requires the image be in sharp focus. The production of a sharp, well-defined image is of greater analytical value than a blurry or fuzzy image. This requires a precise combination of light, lenses, and looking in the right place. Figure 1 shows the relationship between the focal length of a lens and its focal point.
Figure 1. Illustration of how the focal length of the lens (f) and the location where one is looking at the image, or focal point (F), must be in alignment to get a focused image instead of a blurry image. Adapted from .
Under-focus and over-focus both can arise from the incorrect selection of the image plane. Incorrect focus introduces image artifacts on structures, such as a Fresnel fringe. A Fresnel fringe on the inside of a structure’s edge indicates under-focus, and a thicker fringe on the outside of the edge indicates an over-focus, as shown in Figure 2.
Figure 2. Image of a hole in a TEM support film, demonstrating under-focus and over-focus image artifacts.
In many cases, a microscopist will adjust the focus depending in order to highlight specific features in an image. In many cases, a slight defocus is even preferred instead of a perfect focus.
The presence of Fresnel fringes can be used to tell if an image is in focus.
Individual – Focus
In our own lives, setting a goal is an important objective. Maintaining clear focus on the goal is also critical to successfully achieving that goal.
As a microscopist looking to gather an image of a specific structure, say an organelle in a cell, we have set a goal. When setting out to capture an image of that structure, we must look around the many areas of opportunity within that sample to find the specific structure that is our goal. We keep in the focus of our mind the goal, while examining many places on the sample grid until we find the specific area of interest. We then adjust the electron microscope to focus in on just that structure, with constant effort and adjustments until the goal of a well-focused image is achieved.
Similarly, when as individuals we set a goal, we examine the many areas of opportunity and pathways that exist to achieve that goal. We keep in our mind a focus on the goal we are seeking to achieve, as we evaluate the opportunities that bring us closer to achieving that goal. With constant effort and focus to zero in on that point, we are able to achieve our goal.
Most goals worth achieving take time, effort, and determination. When the obstacles come, keeping focused on the goal helps us to drive towards where they are aiming to go. Often, many challenges arise, as well as other opportunities that may be worth pursuing. By both knowing why you have your goal and learning when to say no to opportunities that do not take you to the goal, it will lead to achieving that goal in a shorter time through that focus. In short, maintaining focus will help eliminate the lost productivity from distractions. Keeping your goal in the focal point of where you are looking helps you direct your energy towards the goal.
https://web.eng.fiu.edu/wangc/Lenses%20and%20Apertures%20of%20A%20TEM.pdf, accessed 1/20/21
https://myscope.training/legacy/tem/background/concepts/imagegeneration/stigmationfocus.php, accessed 1/16/21.
About the author:
Robert I. MacCuspie, Ph.D., has over twenty years of experience working at the interface of business and science, at national laboratories, academia and corporations, and is the founder of MacCuspie Innovations which helps companies responsibly commercialize new technologies.