Darkfield Illumination

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Darkfield illumination is one of the various methods of lighting used in microscopy to capture the small, and make it large. This method illuminates the subject through the use of oblique angle lighting to create a glowing and unique presentation of a subject. Oblique lighting eliminates the zero order of illumination which is what sets this method apart from Brightfield illumination. The visible light consists of rays refracted from the subject into the imaging system.

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In order to create Darkfield illumination, a microscopist requires a Brightfield objective and a Darkfield condenser. When executing Darkfield, it is important to have the disc stop equal to the numerical aperture of the objective at the location of the aperture diaphragm exit pupil. Additionally, one must open the field stop fully to ensure the the light is unfocused. Then the operator will raise and lower the substage condenser until the apex of illumination reaches the sample plane.

IMG_9089Advantages of Darkfield Illiminated Photomicrographs

  • Effective for semi transparent subjects
  • Useful for delineating edges of subjects
  • Can reveal internal structures not seen with Brightfield illumination

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Scientific Photography for our 3D World

My name is Jonathan Kozak and I am a third year student in the Photographic and Imaging Technologies Program. Being a bachelor of science student in an art school can present you with can only be described as a bit of an identity crisis when trying to explain your major to other people. However despite this, our curriculum creates a unique environment that stresses a fusion of art and data rather than one or the other.

In the past year, I have found myself enraptured with a technology that combines scientific functionality with a deliverable that is used in many creative workflows. Close Range 3D photogrammetry is the process of taking multiple images from a variety of angles around a subject and combining them to create a scalable and accurate 3D model.

The Geologic Resources division of the National Parks Service has invested in using 3D Photogrammetry for creation and measurement of a variety of assets. The Parks Service has created a variety of models that are viewable by the public on their website. Subjects can cover a variety of topics and make cultural and geologic resources more available to everyone. These models are not only striking representations of real world objects that can serve to educate those who do not have the opportunity to view them in real life, but they also provide valuable insight when viewing objects over time. 3D models created by Parks Service can be used to track degradation of resources and artifacts over time. These efforts tailor their conservation methods and help to preserve the amazing cultural and natural landmarks of our country. (I am currently working with a representative of the NPS Photogrammetry team to obtain an example model, and I am very excited to post it to the blog when it becomes available)