Wollaston prism

Figure Bl.18.8. Differential interferenee eontrast the light beam is split into two beams by a Wollaston prism. The two beams pass the objeet at elosely spaeed positions and give, after interferenee, a eontrast due to the phase differenee.

Noise correlation function, 22 113 Noise equivalent power (NEP), 19 133 Noise spectral density, 19 134-135 Nomarski, Georges, 16 480 Nomarski-modified Wollaston prism, 16 481... 

PC Hobbins and I had in 1950 begun to work on the polarized ultraviolet absorption spectrum of anthracene. We had by that time the use of a quartz Wollaston prism, designed by Dr HG Poole and made by Adam Hilger. It was an important advance, because measurements could be made, one polarized beam at a time, down to a short wavelength limit of about 190 nm. The anthracene solution spectrum shows two absorptions, near 380 nm and near 250 nm. Both are affected by intermolecular forces in the crystal, but could be unravelled to show that the second, very intense, absorption was polarized along the long in-plane molecular axis, in agreement with MO theory. 

DIC means the lens includes a Wollaston prism for differential interference contrast (Section 1.4.4) ... 

Nomarski microscopy is an examination mode using differential interference contrast (DIC). The images that DIC produces are deceptively three-dimensional with apparent shadows and a relief-like appearance. Nomarski microscopy also uses polarized light with the polarizer and the analyzer arranged as in the polarized light mode. In addition, double quartz prisms ( Wollaston prisms or DIC prisms) are used to split polarized light and generate a phase difference. 

Figure 8. Polarization towards Sgr A IRS7 [52]. The data points are compared with the prediction (curve) for aligned silicate core/organic mantle grains. The gap in the data arises from absorption in the cement used in the Wollaston prism.

Figure 17. The optical lay-out of the spectropolarimeter with a deformed Wollaston prism.

Using a Wollaston prism as a polarizer, the light after the polarized modulator becomes partially elliptically polarized. In this case it is necessary to use depolarizers. 

Wollaston prism A type of quartz prism for producing plane-polarized light It deviates the otdin and extraordinary rays in opposite directions by approximately the same amount The Wollaston prism, like the Rochon prism, can be used with ultraviolet radiation. It is named after the inventor William Wollaston (1766-1828). 

Figure 2 shows the differential interferometer used to make video pictures of the jet flow. By extracting the Wollaston prisms and the polarization filters from the set-up a shadowgraph of the jet could be made. Both techniques used together permit a clear picture of the two-phase flow. The typical exposure times were around 10 microseconds. 

In the angle deviation method shown in Fig. 13, light from each port is still collimated first and the circulator is still placed in the collimated beam. However, instead of physically displacing a beam by using a birefringent crystal as in the conventional circulator design, a Wollaston prism is used to introduce different angles for different po-... 

In spectral polarimeters. another monochromator is introduced in front of the polarizer. In this type of ORD equipment, the Wollaston prism and polarizer are often combined by pivoting the polarizer to and from in a defined angle. CD equipment is often provided as an additional device for classical absorption spectrometry. With these devices, absorption of left and right circular-polarized light can be measured independently. For this, combinations of Rochon prisms (as polarizers) and Fresnel quartz rhombic prisms (for production of circular-polarized light) are used [34]. Equipment of this type is shown in Figure 22. 

Nomarski Differential Interference Contrast (DIC). In 1955 the physicist George Nomarski simplified the two-beam interference microscope in a way that it became available for routine microscopy [11 (Fig, 6), DIC uses modified Wollaston prisms (Fig. 6B). lying outside the focal... 

Figure 6. A) Image path of a Iwo-beam interference microscope B) Nomarski prism with direction of optical axes and position of interference plane indicated a) Polarizer (45°) b) First Wollaston prism c) Condenser d) Specimen e) Objective f) Second Wollaston prism g) Analyzer (135°) h) Intermediate image Contrast is generated by a phase shift of the polarized and prism-split illuminating beam.s, which are combined by the second prism...

The other method uses an interferometer. In Figure 2.52b, a beam linearly polarized at 45° from vertical is split into two beams by a Wollaston prism. One of the two beams passes a sample ceU, and the other beam passes a reference cell. When there is a difference in the refractive index between the two fluids, one of the beams is delayed compared with the other, resulting in a phase shift. When the two beams are coupled by another prism, they form a circularly polarized light. A quarterwave plate converts it into a linearly polarized beam. With the analyzer (another polarizer) adjusted to be extinct when there is no phase shift, the intensity of light though the analyzer is proportional to the phase shift. The latter is proportional to An. 

F, optical filter P., P- polarizers W, 1 2 wollaston prisms A, analyzing directions PM, photomultiplier T, temperature chamber... 

It can be assumed that each of the beams focused on the Wollaston prism consists of two such perpendicular beams which, after the quarter-wave plate, result in two circularly polarized beams of opposite rotation. These beams will interfere with each other to yield the original linearly polarized beam. A second polarizer is placed at an angle (90-b) to the first one, allowing 35% of the signal to reach the photomulitiplier. A filter transmitting light at 546 nm precedes the photomultiplier. 

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