Classifications

• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/10—Beam splitting or combining systems
  • G02B27/14—Beam splitting or combining systems operating by reflection only
  • G02B27/145—Beam splitting or combining systems operating by reflection only having sequential partially reflecting surfaces
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
  • G02B27/283—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising used for beam splitting or combining

Definitions

• This invention relates to an optical light beam splitting device, and more particularly, to an optical beam splitting device for use in an optical data storage device. Even more particularly, the invention relates to an improved optical beam splitting device, wherein improved component alignment is achieved by special selection of optical component shapes and special optical coatings.
• beam splitter devices for separating discrete beams of light within optical systems is well known in the prior art due to the need to conveniently combine and/or separate two discrete light beams having different wavelengths traveling the same optical path. This is basically accomplished through use of selective thin film coatings and cube or plate beam splitter components.
• one such device is the cube cluster in which six identical prisms have optical thin film coatings applied to the prism hypotenuses. These prisms are bonded together to form three separate optical cubes, which in turn are then bonded onto -a planar surface carrier plate in precise alignment with respect to each other, forming the desired beam splitting device assembly.
• the present invention addresses this problem by providing a low cost, simple beam splitter design, wherein an accurate, reliable, easily assembled device is disclosed.
• the present invention is a simplified dichroic optical beam splitter wherein all component elements are securely bonded together to form a single unit device. This allows for the physical reduction in size of the device and, further, diminishes light beam intensity losses by reducing the total number of interfaces through which the light beam must travel.
• the present invention is also a multi-function device.
• the optional path provides for combining discrete light beams which exit the device in a coaxial parallel fashion, and discrete light beams entering said exit point are separated and transmitted along selective discrete paths.
• the entire device consists of four optical prism elements securely bonded together to form a single unit.
• the three junctions created by bonding the four elements together contain a discriminating coating substance, for selection of either polarization or wavelength of the incident light beams, thereby having either transmitting or reflecting characteristics with respect to the planar polarization or the wavelength of said incident light beams.
• the present invention requires fewer component elements for assembly, as all elements are bonded into a single unit. This also eliminates the air-to-glass interfaces, and therefore minimizes light intensity losses within the device.
• FIGURE 1 is a schematic representation of a .prior art cube-cluster dichroic beam ' splitter showing the combining of two discrete light beams having different wavelengths, and further, depicting the separation of two light beams entering the cluster in a coaxial fashion, exiting in opposite directions.
• FIGURE 2 is a representative schematic diagram of the present invention, a single unit dichroic beam splitting device, with light beam combining and separating functions.
• FIGURE 1 shows a prior art light beam splitter 1 which is an optical cube cluster.
• the three optical cubes 2-4 shown are spatially separated a dimension convenient for assembly and alignment.
• the three said cubes 2-4 are assembled from identical right triangular prisms securely bonded together to form discriminating interfaces A, B and C.
• discriminating interfaces A ⁇ B are planar polarized such that each interface reflects planar S-Polarized light beams and transmits planar P-Polarized light beams.
• Discriminating interface C comprises a dichroic coating substance having sensitivity for transmitting light beams of a first wavelength (e.g., 835 nanometers) and reflecting light beams of a second wavelength (e.g., 633 nanometers).
• the above described beam splitter 1 constitutes a convenient device for combining or separating two discrete beams of light sharing the same optical path.
• a first S-Polarized light beam 5 impinging upon optical cube 4 is transmitted to interface B and reflected toward cube 3.
• Said first beam 5 upon impinging optical cube 3 is transmitted through to interface C and reflected, by interface C to exit cube 3 passing through quarter wave plate 9, which circularly polarizes the beam 5.
• Beam 5 is then reflected off planar reflector 10.
• a second P-Polarized light beam 6 impinging upon optical cube 2 is transmitted through the discriminating interface A without deviation toward optical cube 3.
• Said second beam 6 upon impinging upon optical cube 3 is transmitted through the dichroic interface C, and exits the optical cube 3 coaxial with first light beam 5, also passing through quarter wave plate 9 and impinging reflector 10, thus completing the beam combining function of the
• the circularly polarized beams 7 and 8 are again linerly polarized but now changed from P- to S- or S- to P- polarization respectively.
• the reflected beam 7 is still reflected off surface C but passes through surface B, while beam 8 still passes through surface C and is also reflected by surface A. This separates the reflected beam from the incident, which is part of the intended purpose of the invention.
• the three component optical cubes 2-4 are not only spatially separated, but also separately mounted on a flat planar carrier plate 12. Each optical cube is securely bonded into its respective position on the plate 12 in order to form the single-unit device 1.
• FIGURE 2 is a schematic diagram of a dichroic beam splitter 13 configured according to the present invention.
• the current invention comprises a total of four discrete elements 14-17 securely bonded together forming a single unit.
• Elements 14 and 17 are identical right triangular prisms while elements 15, a parallelogram shape, and 16, a trapezoidal shape, are geometrically unique prisms having 45° interfaces with respect to the device.
• the interfaces A, B and C formed by securely bonding the four discrete • components 14-17 into a single unit replicate the interfaces previously described in FIGURE 1.
• the light beam combining and separating functions are repetitive of those previously described.
• the reduction to four discrete elements for the present invention can reduce the size of the assembled device 13. Bonding of the four discrete elements 14-17 into a single unit 13 fixedly -5-
• optical prism 14 is securely bonded to prism 15 to form interface A oriented to create a polarizing beamsplitter surface. Additionally, interface A establishes the positioning, as well as the alignment, of the two prisms with respect to each other.
• the dichroic light beam discriminating interface B is formed by the bonding of prisms 15 and 16, again establishing alignment and positioning of said elements.
• the fourth element, prism 17 in contact with prism 16 establish the polarizing interface C as well as providing alignment in order to complete the dichroic beam splitter device 13.
• the flat planar carrier plate 12 of prior art is eliminated as a component of the device assembly 13, thereby further reducing of the weight and bulk of the device. Also, elimination of air gaps within the optical path of the present invention reduces transmission losses.
• two discrete light beams 5 and 6 are combined as previously described and exit the device 13 passing through external • quarter wave plate 9 onto reflecting surface 10.
• the two combined light beams 7 and 8 are then reflected back through the quarter wave plate 9, and finally exit the device after reflecting off surfaces C and A, respectively.

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Optical Elements Other Than Lenses (AREA)

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• 1984
  • 1984-10-03 EP EP19840903742 patent/EP0156901A1/de not_active Withdrawn
  • 1984-10-03 WO PCT/US1984/001590 patent/WO1985001590A1/en not_active Ceased

Non-Patent Citations (1)

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