Optical axis

If the translation Xt is transversal to optical axis (for example parallel to axis x) (Figure lb) ... 

Figure 1. shows the measured phase differenee derived using equation (6). A close match between the three sets of data points can be seen. Small jumps in the phase delay at 5tt, 3tt and most noticeably at tt are the result of the mathematical analysis used. As the cell is rotated such that tlie optical axis of the crystal structure runs parallel to the angle of polarisation, the cell acts as a phase-only modulator, and the voltage induced refractive index change no longer provides rotation of polarisation. This is desirable as ultimately the device is to be introduced to an interferometer, and any differing polarisations induced in the beams of such a device results in lower intensity modulation. 

The extension of the voxel in a radial direction gives infomiation on the lateral resolution. Since the lateral resolution has so far not been discussed in temis of the point spread function for the conventional microscope, it will be dealt with here for both conventional and confocal arrangements [13]. The radial intensity distribution in the focal plane (perpendicular to the optical axis) in the case of a conventional microscope is given by... 

Figure 9.22 illustrates how a CARS experiment might be carried out. In order to vary (vj — V2) in Equation (9.18) one laser wavenumber, Vj, is fixed and V2 is varied. Here, Vj is frequency-doubled Nd YAG laser radiation at 532 nm, and the V2 radiation is that of a dye laser which is pumped by the same Nd YAG laser. The two laser beams are focused with a lens L into the sample cell C making a small angle 2a with each other. The collimated CARS radiation emerges at an angle 3 a to the optic axis, is spatially filtered from Vj and V2... 

Unstretched PPX films exhibit an inherent negative birefringence, the optical axis of which is perpendicular to the plane of the film. The refractive index along the optical axis is lower than the refractive index observed in the plane of the film, the difference being = —0.075 0.001 (42). Where... 

Radiation Effects. Alpha sihcon carbide exhibits a small degree of anisotropy in radiation-induced expansions along the optical axis and perpendicular to it (58). When diodes of sihcon carbide were compared with sihcon diodes in exposure to kradiation with fast neutrons (59), an increase in forward resistance was noted only at a flux about 10 times that at which the increase occurs in a sihcon diode. In general, it appears that sihcon carbide, having the more tightly bound lattice, is less damaged by radiation than sihcon. 

Spindle stages and universal stages allow a sample to be placed in any orientation relative to the microscope s optical axis. 

Because the laser beam is focused on the sample surface the laser power is dissipated in a very smaU area which may cause sample heating if the sample is absorbing and may cause break-down if the sample is susceptible to photodecomposition. This problem sometimes may be avoided simply by using the minimum laser power needed to observe the spectrum. If that fails, the sample can be mounted on a motor shaft and spun so that the power is dissipated over a larger area. Spinners must be adjusted carefully to avoid defocusing the laser or shifting the focal spot off the optic axis of the monochromator system. 

An example of a serial-recording EEL spectrometer is shown in Eig. 2.33 it features a magnetic prism system which was constructed for a TEM/STEM of the type JEOL JEM lOOS [2.199, 2.200]. Its second-order aberrations are corrected by curved pole-piece boundaries, an additional field clamp, and two extra hexapoles acting as stig-mators. The electron beam can be adjusted relative to the optical axis by use of several deflection coils. A magnetic round lens is positioned just in front of the prism to... 

The length of the instrument from the slit to the end of the plate holder is about 1.2 metres, and it is supported on a massive base which raises the optical parts about 30 cm above bench level. An optical bar of steel is attached to the base of the instrument, from which it projects about 90 cm it is parallel with the optical axis. The bar serves to carry lenses, an arc and spark stand (Gramont stand) for holding samples, and other ancillary equipment. 

Figure 5. Spherical aberration rays corresponding to different aperture angles focus at different locations along the optical axis.

If the angles are small i.e. close to the optical axis, then the paraxial approximation can be made ... 

For a spherical surface such as a lens or mirror, we are able to determine the angle of refraction, or reflection from the ray height at that surface. The angle the surface normal makes relative to the ray as a function of height h above the optical axis is given by... 

Our coordinate system has z parallel to the optical axis, y is vertical and x comes out of the page. 

All conics can be expressed via one equation, which describes the position parallel to the optical axis, z as a function of the normalized height above the optical axis r. 

At an 8m telescope in a good site, ro 0.15m and a wind velocity of V 30m/s, To,tilt 0.12 s at A = 0.5/xm to 1.2 s at A = 5/rm. It scales as A. To,tilt is 10 times larger than the wavefront coherence time. Thus both deflections to and from the mesosphere approximately cancel each other and the LGS apparent location is fixed with respect to the optical axis. The principle of inverse return of light applies one does not know the LGS location in the sky, and the tilt cannot be measured. 

We have applied FCS to the measurement of local temperature in a small area in solution under laser trapping conditions. The translational diffusion coefficient of a solute molecule is dependent on the temperature of the solution. The diffusion coefficient determined by FCS can provide the temperature in the small area. This method needs no contact of the solution and the extremely dilute concentration of dye does not disturb the sample. In addition, the FCS optical set-up allows spatial resolution less than 400 nm in a plane orthogonal to the optical axis. In the following, we will present the experimental set-up, principle of the measurement, and one of the applications of this method to the quantitative evaluation of temperature elevation accompanying optical tweezers. 

By considering only elastic scattering events, the interaction of the specimen with the electron beam can be described through a complex transmission function (object wave-function) 0(f) which represents the ratio between the outgoing and the incoming electron wave-functions f = (x, y) is a two-dimensional vector lying on a plane perpendicular to the optic axis z which is parallel, and in the same direction, to the electron beam. In the standard phase object approximation ... 

The integral is taken along a trajectory I parallel to the optical axis, passing inside and outside the specimen, and which must include stray fields V(f, z) and Az(r, z) are the electrostatic potential and the z component of the magnetic vector potential A(f,z), respectively E a factor that becomes the accelerating voltage in the non-relativistic... 

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