Resolution distance

Dark-field methods do not help to improve the resolving power of a microscope. A small scattering particle is seen indirectly as a weak blur. Two particles must be separated by the resolution distance 8 to... 

Optical memory density is ultimately limited by the diffraction of electromagnetic waves. Present techniques have almost reached this limitation in those optical memories that are commercially available as CDs or DVDs. Even with an infinitely large objective lens with high numerical-aperture (NA) value, the bit data resolution distance for recording and reading cannot be reduced to less than half of the beam wavelength. 

Let us define as the number of bonds in a chain segment comprised between two consecutive entanglement points, namely, two points where we assume the chain is forced to pass through because of the constraints exerted by the surrounding chains. Since the resolution distance D of our tube image [see Eqn. (2.1.50)] is conceptually close to the distance between entanglement points, we may write as a definition... 

Table 7.5. Variation of optimum crystal to plate distance as a function of spot to spot resolution distance. From Cruickshank et al (1991).

Spot to spot resolution distance (mm) Optimum crystal to plate distance (mm) No. of RLPs free from energy or spatial overlaps % of RLPs intercepted and free from overlaps... 

R Resolution distance between the peaks, which is really what interests the normal" user. The resolution is influenced by the above three factors, which again means that a separation optimization can be reached exclusively through change of k, a and N. The most effective way to reach an improvement of the resolution is through a change of the selectivity (see Tips Nos. 40 and 41). 

Altenbach C, Kusnetzow AK, Ernst OP, Hofmann KP, Hubbell WL (2008) High-resolution distance mapping in rhodopsin reveals the pattern of helix movement due to activation. Proc Natl Acad Sci USA 105(21) 7439-7444... 

Spatial resolution Distance over which a signal from some abruptly appearing interface climbs from 16% of its maximum intensity to 84% (2 standard deviations)... 

Consequently, measurements of rates and efficiencies of energy transfer in non-diffusing systems can determine the distances between groups. If A and Q are attached to specific sites in polymers, important high resolution distance information can be obtained. 

The divergent shape of the beam provides facilities for magnification in the distances of the source to detector and of the sources to the axis of rotation, which used in conjunction with a microfocus x-ray source opens the way to high resolution. 

The geometrical resolution or the resulting unsharpness in the radioscopic image is adjusted by the workpiece-detector distance. The relation between the focus-... 

It is shown how phase contrast X-ray microtomography can be realised with a (commercial) polychromatic X-ray microfocus tomograph provided the source size and the resolution of the detector are sufficiently small and the distance between source and detector is sufficiently large. The technique opens perspectives for high resolution tomography of light objects... 

For this experiment, as well as for the microtomography ( 3.2) we used the commercial desktop microtomography system Skyscan 1072 [5], the setup of which is sketched in Figure 1. For this instrument, which is designed to study relatively large objects with a diameter up to 50 mm, the source size is 8 pm, the distance source-detector is about 50 cm and the effective resolution of the detector is about 80 pm. For this system and this object, the global effective resolution a is estimated to be of the order of 50 to 100 pm [6]. 

This corresponds to the physician s stethoscope case mentioned above, and has been realized [208] by bringing one leg of a resonatmg 33 kHz quartz tiinmg fork close to the surface of a sample, which is being rastered in the x-y plane. As the fork-leg nears the sample, the fork s resonant frequency and therefore its amplitude is changed by interaction with the surface. Since the behaviour of the system appears to be dependent on the gas pressure, it may be assumed that the coupling is due to hydrodynamic mteractions within the fork-air-sample gap. Since the fork tip-sample distance is approximately 200 pm -1.120), tire teclmique is sensitive to the near-field component of the scattered acoustic signal. 1 pm lateral and 10 mn vertical resolutions have been obtained by the SNAM. 

This method relies on the simple principle that the flow of ions into an electrolyte-filled micropipette as it nears a surface is dependent on the distance between the sample and the mouth of the pipette [211] (figure B 1.19.40). The probe height can then be used to maintain a constant current flow (of ions) into the micropipette, and the technique fiinctions as a non-contact imaging method. Alternatively, the height can be held constant and the measured ion current used to generate the image. This latter approach has, for example, been used to probe ion flows tlirough chaimels in membranes. The lateral resolution obtainable by this method depends on the diameter of the micropipette. Values of 200 nm have been reported. 

Compared witii other direct force measurement teclmiques, a unique aspect of the surface forces apparatus (SFA) is to allow quantitative measurement of surface forces and intermolecular potentials. This is made possible by essentially tliree measures (i) well defined contact geometry, (ii) high-resolution interferometric distance measurement and (iii) precise mechanics to control the separation between the surfaces. 

The preparation of the reflecting silver layers for MBI deserves special attention, since it affects the optical properties of the mirrors. Another important issue is the optical phase change [ ] at the mica/silver interface, which is responsible for a wavelength-dependent shift of all FECOs. The phase change is a fimction of silver layer thickness, T, especially for T < 40 mn [54]. The roughness of the silver layers can also have an effect on the resolution of the distance measurement [59, 60]. 

Frantz P, Agrait N and Salmeron M 1996 Use of capacitance to measure surface forces. 1. Measuring distance of separation with enhanced spacial and time resolution Langmuir 12 3289-94... 

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