21. This is required by the reversibility ( or unitarity ) of the quantum evolution of the beam splitter . 22. Beam splitters with single mode fiber for PON networks use the single mode behavior to split the beam.23. For example, a variation in reflectivity ( and thus also in transmittance ) of a beam splitter , where 24. Customarily the Hong Ou Mandel effect is observed using two photodetectors monitoring the output modes of the beam splitter . 25. An additional photomultiplier system viewed a beam splitter in the optical path and was used as a star mapper. 26. When a photon enters a beam splitter , there are two possibilities : it will either be reflected or transmitted. 27. These then hit a beam splitter , which sends photons back to the barium borate crystal with 50 % probability. 28. Adding a beam splitter allows the viewer to see the reticle and the field of view, making a reflector sight. 29. On steadicam and remote head or crane operation, the viewfinder and beam splitter is often removed because its not needed. 30. A beam splitter divides the laser light into two paths, one of which has a phase modulator as described above.
