Similarly to the previous setup, two parallel beams with a variable delay are generated, then focused into a second-harmonic-generation crystal ( see nonlinear optics ) to obtain a signal proportional to ( E ( t ) + E ( t-\ tau ) ) ^ 2.
42.
Aimed straight up from Battery Park City and visible _ the designers hope _ for miles around, two parallel beams created by 88 powerful searchlights will glow every night from dusk to 11 p . m ., cloud cover, helicopter traffic and bird migration permitting.
43.
In Russia, Finland, and a few nearby countries, a "'sokha "'( ) is a light wooden ard, consisting of two body ards, with their parallel beams forming the two shafts for a single horse-drawn tillage implement with two socket shares ( @ 0AA > E0 ).
44.
:: If I had to do this, I'd make a long, stiff pole about the same length as the depth I intended to dig . . . and mount a visible light laser at right angles at each end, both carefully aligned to project perfectly parallel beams.
45.
The incoming elementary parallel beams ( illustrated by the colors blue, green and red ) are converging in the back focal plane of the lens with the distance of their focal point from the optical axis being a ( monotonous ) function of the angle of beam inclination.
46.
Perhaps the most widespread use of Fresnel lenses, for a time, occurred in automobile headlamps, where they can shape the roughly parallel beam from the parabolic reflector to meet requirements for dipped and main-beam patterns, often both in the same headlamp unit ( such as the European H4 design ).
47.
Primary beam radiation passes through the radiolucent strips as it travels roughly parallel to them, but scattered radiation which has, almost by definition, deviated from the parallel beam, cannot easily pass through the grid as it encounters the lead strips at an angle, and is attenuated, or lost, from the beam.
48.
Cross sections can be computed for any sort of process, such as capture scattering, production of neutrons, etc . In many cases, the number of particles emitted or scattered in nuclear processes is not measured directly; one merely measures the attenuation produced in a parallel beam of incident particles by the interposition of a known thickness of a particular material.
49.
NOTE that the circular disc at the end of the prism will act as a'point source'of light with diameter ( blurry-ness ) similar to the diameter of the disc-therfore placing a lens with the disc at the focal length of the lens should produce a roughly parallel beam . ( thin cylinders and short focal length lens help here to reduce the width of the beam .)
