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Cylindrical Optics - 12567 Cylindrical Optics

Multielement Lenses Cylindrical lenses are used in applications requiring magnifica-tion in a single dimension. The same theory and formulas that apply to spherical lenses also apply to cylindrical lenses, although theyimage in only one dimension, not two. Cylindrical lenses are usedto transform a point image into a line image and to change image height without changing width, or vice versa.Melles Griot offers two families of cylindrical lenses: stan-dard-grade glass and precision-grade synthetic fused silica.
APPLICATION NOTE

Using Cylindrical Lenses toCollimate Nonsymmetrical Beams

Cylindrical Optics $ Standard-grade glass lenses, manufactured from Schott BK7glass, are an excellent compromise between cost and perfor-mance. Typical applications include slit and line detector arrayillumination, laser line generators, and asymmetrical laser beam expanders. Cylindrical lenses follow the same theories andformulas as spherical lenses, although they image inone dimension, not two. For example, to collimate the output of a diode laser whose beam divergenceis $ Precision-grade synthetic fused-silica lenses are manufacturedto tighter tolerances than standard-grade glass lenses, withmuch less wedge and exceptional surface accuracy. In addi-tion, they have several distinct advantages over BK7 includingawider spectral range (180–2100 nm), low disper- sion, low thermal-expansion coefficient, and better resistanceto thermal shock and scratches. These lenses can be usedforapplications such as bar-code scanning, holography, opti- cal information processing and computing, and laser projec-tion, where the higher cost is offset by the superior wavefrontquality.Two shapes are available in each family: plano-convex andplano-concave. Plano-convex lenses have a positive focal length andthey focus, or converge, light to a line; plano-concave lenses have a negative focal length and diverge light away from a line. The optics,as listed, are uncoated; however, antireflection and reflective coat-ings may be ordered by appending the appropriate coating suffix from Chapter 5, v
2 # v
1 , we first collimate the beam in onedimension with the first cylindrical lens and then collimate the orthogonal dimension with a second cylindrical lens. The ratio of the two focal lengthsshould be approximately equal to the ratio of thetwo beam divergences: The lenses should be positioned at their respectivefocal lengths from the diode laser to create a collimated beam.The principal planes of the two lenses should beseparated at a distance equal to the difference of their focal lengths,
Mirrors Optical Coatings .
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2 w 1 2121 =
Prisms andRetroreflectors f
dimensions in mm 2 4 f
1 . The actual spacingbetween the plano surfaces is
Beamsplitters,Windows, Optical Flats f
b2 4 f
b1 . The convexsurfaces should face the collimated rays to minimizeaberrations.Care must be taken to ensure that the beamwidth ateach lens does not exceed the lens clear aperture.Since each lens is placed one focal length from thediode laser, maximum beam diameter at each lens can be determined from
Polarization Components 1 == 2 and
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Filters 8.2

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Cylindrical Optics

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