Imaging materials. Photographic film and papers. Method for determining the resistance of photographic emulsions to wet abrasion

Equidensitometry as developed by E. Lau and W. Krug has been little used in the analysis of ordinary electron photomicrographs, yet its application to the high voltage electron images proves merits of this procedure. Proper sets (families) of equidensities as shown in the next page are able to reveal the contour map of mass thickness distribution in thick noncrystalline specimens. The change in density of the electron micrograph is directly related to the mass thickness of corresponding area in the specimen, because of the linear response of photographic emulsions to electrons and the logarithmic relation between electron opacity and mass thickness of amorphous object.This linearity is verified by equidensitometry of a spherical solid object as shown in Fig. 1a. The object is a large (1 μ) homogeneous particle of polystyrene. Fig. 1b is a composite print of three equidensities of the 1st order prepared from Fig. 1a.

Download Full-text

The Application of Ultra-Thin Sectioning Techniques to Non-Biological Samples

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101402 ◽

1968 ◽

Vol 26 ◽

pp. 332-333

Author(s):

C. F. Oster

Keyword(s):

Biological Sciences ◽

Epoxy Resin ◽

Cross Sections ◽

Biological Samples ◽

Industrial Applications ◽

Photographic Film ◽

Silver Particles ◽

Thin Sectioning ◽

Embedding Medium

Although ultra-thin sectioning techniques are widely used in the biological sciences, their applications are somewhat less popular but very useful in industrial applications. This presentation will review several specific applications where ultra-thin sectioning techniques have proven invaluable.The preparation of samples for sectioning usually involves embedding in an epoxy resin. Araldite 6005 Resin and Hardener are mixed so that the hardness of the embedding medium matches that of the sample to reduce any distortion of the sample during the sectioning process. No dehydration series are needed to prepare our usual samples for embedding, but some types require hardening and staining steps. The embedded samples are sectioned with either a prototype of a Porter-Blum Microtome or an LKB Ultrotome III. Both instruments are equipped with diamond knives.In the study of photographic film, the distribution of the developed silver particles through the layer is important to the image tone and/or scattering power. Also, the morphology of the developed silver is an important factor, and cross sections will show this structure.

Download Full-text

Stereo modeling of HVEM specimens by serial tilting and computer graphics

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100141913 ◽

1986 ◽

Vol 44 ◽

pp. 34-35

Author(s):

J.R. McIntosh ◽

D.L. Stemple ◽

William Bishop ◽

G.W. Hannaway

Keyword(s):

Computer Graphics ◽

Analytical Methods ◽

Photographic Film ◽

Complex Structures ◽

Multiple Objects ◽

Multiple Images ◽

3 Dimensional

EM specimens often contain 3-dimensional information that is lost during micrography on a single photographic film. Two images of one specimen at appropriate orientations give a stereo view, but complex structures composed of multiple objects of graded density that superimpose in each projection are often difficult to decipher in stereo. Several analytical methods for 3-D reconstruction from multiple images of a serially tilted specimen are available, but they are all time-consuming and computationally intense.

Download Full-text

Factors in Photographic Emulsions for Low Dose Electron Crystallography

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s143192760000101x ◽

1980 ◽

Vol 38 ◽

pp. 230-231

Author(s):

T.W. Jeng ◽

W. Chiu

Keyword(s):

Radiation Damage ◽

Low Dose ◽

Damage Effect ◽

Photographic Emulsion ◽

Electron Crystallography ◽

Electron Microscopic ◽

X Ray ◽

Signal Contrast ◽

Diffraction Patterns ◽

Photographic Emulsions

With the advances in preparing biological materials in a thin and highly ordered form, and in maintaining them hydrated under vacuum, electron crystallography has become an important tool for biological structure investigation at high resolution (1,2). However, the electron radiation damage would limit the capability of recording reflections with low intensities in an electron diffraction pattern. It has been demonstrated that the use of a low temperature stage can reduce the radiation damage effect and that one can expose the specimen with a higher dose in order to increase the signal contrast (3). A further improvement can be made by selecting a proper photographic emulsion. The primary factors in evaluating the suitability of photographic emulsion for recording low dose diffraction patterns are speed, fog level, electron response at low electron exposure, linearity, and usable range of exposure. We have compared these factors with three photographic emulsions including Kodak electron microscopic plate (EMP), Industrex AA x-ray film (AA x-ray) and Kodak nuclear track film (NTB3).

Download Full-text