Projection microscope

For control or calibration purposes, film thickness can be determined by mounting a sectioned specimen and measuring the oxide film thickness directly on the screen of a projection microscope at a known magnification. Alternatively, the loss in weight of an anodised sample of known area may be found after the film has been stripped in a boiling solution made up as follows ... 

Figure 5.15 shows a ray diagram for a light-optical projection microscope. The light source is placed behind a condenser system which collects the light which is diverging from the source and illuminates the specimen. The presence of the variable aperture near to the condenser lens permits control of the area of the specimen which is... 

Figure 5.15. The optical system for a transmission projection microscope.

In a point projection microscope, the image magnification is given by... 

Figure 1. (a) Schematic diagram of a laser photoion projection microscope and (b) spectrally selective multistep photoionization scheme for absorbing centers (color centers, molecular chromophores, etc.) by ultrashort laser pulses. 

The first requirement is that the test piece should be dimensionally accurate but this is not dealt with in ISO 23529, the necessary tolerances and dimensions remaining a subject for the individual test method. The important dimensions can be conveniently checked on a cut test piece using a projection microscope, but the dimensions of the cut test piece will not necessarily be identical with the dimensions of the die because of the pressure of the blade deforming the rubber. In the majority of tests it is the test piece dimensions which are those specified. 

Dimensions such as the width of a dumb-bell or the depth of a nick in a tear specimen will be less than 30 mm but could not be measured with a dial gauge. Because of the virtual impossibility of applying a known pressure, such measurements must be made in an essentially contactless manner. For low precision, calipers or a rule may suffice but for readings to 0.01 mm a travelling microscope or projection microscope is most suitable, and this is specified in ISO 23529 Method D and applies also to dimensions over 30mm. Projection microscopes also find use in examining profiles and for rapid swelling tests (see Chapter 16, Section 2.1). 

Cawood where the series is much closer. He also described a graticule, having nine circles in a V2 progression of sizes, for use with the projection microscope [71]. This was incorporated in a projection screen instead of being in the eyepiece and was adopted by the British Standards Organization [11]. 

Fairs [79] used a projection microscope for training purposes. This technique can also be used for size analysis [80] but is not recommended for particles smaller than 2 pm. Hamilton et. al. [81 c/7.82] demonstrated the need to train operators and showed that gross count differences on the same samples at different laboratories were much reduced after interlaboratory checks. 

Projection microscope techniques such as the method used for measuring wool fiber diameter (sec ASTM D 2130 and ISO 137). 

The microscopy and projection microscope techniques are notoriously subject to error, suffering as they do from operator error, calling for considerable dexterity by the operator in cutting and manipulation, and at present 1 am not aware of any statistical precision data on the methods (although see ASTM D 578 ). It is unlikely that reproducibility R will ever approach a level enjoyed by some laboratories in repeatability r tests. 

ISO 105. Part XIO. 199.1 Assessment of migration of textile colors into poly vinylchloride coatings. ISO 137. 1975 Wool - Determination of fiber diameter -Projection microscope method. 

Photographs of the masks were taken before and after die tests by Projektina projection microscope. The photos are shown in Figure 1. As can be seen fimn the jdtotos after low velocity spray, masks collected more particules. 

X-ray projection microscopy (XPM) Conceptually, a projection microscope is quite simple and relies on shadow enlargement from a point source of X-rays (Figure 4B). Earlier an electron microscope type column produced a small and bright electron spot that in turn created an X-ray spot of sufficient brightness and small diameter (0.1-1 pm) to provide useful magnification of several hundred times. For soft X-rays, Fresnel diffraction limits the resolution however, for hard X-rays, the image resolution is determined entirely by the X-ray emitting volume and the electron beam current. The usual resolution of these instruments was not less than 0.5 pm. 

The same spatial coherence available at synchrotrons can also be obtained with a microfocus X-ray tube with a very small source size similar to the projection microscope but with a significant source-sample distance (Li lm). It was shown that a monochromatic beam is not necessary and the polychromatic output of the X-ray tube can be used. 

The analysis of the loop shape was carried out using a projection microscope. Last picture just before and after failure of a fibre is presented in Figure 3. 

Starting from the top point of fibre loop just before its failure the width of loop was measured at 39 yum intervals along its length with the use of projection microscope, (magnification 130 x). The diagram representing mean values of half width of loop based on results from 19 fibres is presented in Fig.4 a and b. The numerical values are given in the Table 1. 

---