Lap dissolve slide projector

Claim 2

A lap dissolve slide projector, comprising: means defining first and second projecting stations each for receiving and supporting a slide or the like to be projected; means for forming a first unpolarized visible illuminating light beam and a second unpolarized visible illuminating light beam, said light beam forming means being positioned to illuminate a slide supported at said first projecting station with said first illuminating beam and tO illuminate a slide supported at said second projecting station with said second illuminating beam; polarizing beam splitter means having first and second light entrance paths and a first light exit path, said beam splitter means being operable to generate from an unpolarized visible input light beam received along said first entrance path a first plane polarized output light beam directed along said first exit path, said beam splitter means being operable to generate from an unpolarized visible input light beam received along said second entrance path a second plane polarized output light beam directed along said first exit path which is polarized 90* apart from said first output beam; light directing means positioned with respect to said projecting stations and beam splitter means for directing said first illuminating beam as an input along said first entrance path and said second illuminating beam as an input along said second entrance path; projection lens means for projecting slide images on a selected viewing area, said projection lens means being positioned to receive and project output beams from said beam splitter first exit path; and first plane polarizing means positioned to intercept output beams from said beam splitter first exit path, the polarization orientation of said first plane polarizing means being selectively changeable between one position aligned with the polarization of said first output beam and another position 90* out of alignment therewith whereby a lap dissolve transition may be made on a selected viewing area from the projection of the image of a slide supported at one of said projecting stations to the image of a slide supported at the other of said projecting stations by rotating said first polarizing means between said one and other positions.

Claim 3

The invention defined in claim 1, wherein said polarizing beam splitter is a compound prism made up of two prisms having flat base surfaces with a multilayer material of substantially uniform thickness interposed between said base surfaces, the indices of refraction of said prisms and the layers of said multilayer material having preselected valves to define a selected Brewster''s angle at the interfaces of said prisms and multilayer material.

Claim 4

The invention defined in claim 2, wherein: the indices of refraction of said prisms and of the layers of said multilayer material are preselected to define a Brewster''s angle of 45*; and said first exit path is substantially perpendicular to said first entrance path and in alignment with said second entrance path, each of said entrance and exit paths intersecting the plane defined by said multilayer material at approximately a 45* angle.

Claim 5

The invention defined in claim 1, wherein: said beam splitter means also has a second light exit path, said beam splitter means being operable to divide an unpolarized visible input light beam received along said first entrance path into said first plane polarized output light beam directed along said first exit path and a third plane polarized output light beam directed along said second exit path which is polarized 90* apart from said first output beam, said beam splitter means further being operable to divide an unpolarized visible input light beam received along said second entrance path into said second plane polarized output light beam directed along said first exit path and a fourth plane polarized output light beam directed along said second exit path which is plane polarized 90* apart from said second output beam and hence polarized 90* apart from said third output beam; and including: means for previewing the image of slide to be projected, said preview means being positioned to receive output beams from said beam splitter second exit path and being operable to form the image of a slide supported in said first or second projecting station; and second plane polarizing means posiTioned between said beam splitter preview means to intercept output beams from said beam splitter second exit path, the polarization orientation of said second plane polarizing means being selectively changeable between one position aligned with the polarization of said fourth output beam and another position 90* out of alignment therewith whereby the previewing of the image of a slide supported at one or the other of said projecting stations may be selectively controlled by the orientation of said second plane polarizing means.

Claim 6

The invention defined in claim 4, including control means for maintaining the orientations of said first and second polarizing means in phase and coordinately rotating said polarizing means together selectively between their one and other positions so that when the image of a slide in one of said projecting stations is being projected the image of a slide in the other of said projecting stations is being previewed.

Claim 7

The invention defined in claim 5, wherein said polarizing beam splitter is a compound prism made up of two prisms having flat base surfaces with a multilayer material of substantially uniform thickness interposed between said base surfaces, the indices of refraction of said prisms and the layers of said multilayer material having preselected valves to define a selected Brewster''s angle at the interfaces of said prisms and multilayer material.

Claim 8

The invention defined in claim 6, wherein: the indices of refraction of said prisms and of the layers of said multilayer material are preselected to define a Brewster''s angle of 45*; and said entrance paths are substantially perpendicular to each other and said exit paths are substantially perpendicular to each other, said second exit path being aligned with said first entrance path and said first exit path being aligned with said second entrance path, each of said entrance and exit paths intersecting the plane defined by said multilayer material at approximately a 45* angle.

Claim 9

In a lap dissolve slide projector wherein slides in first and second projecting stations are, respectively, illuminated by first and second light beams, said first and second light beams being each divided into a first beam portion which is projected from said slide projector by a projection lens and a second beam portion which is not projected from said slide projector, the first portions of said first and second light beams being plane polarized 90* apart and said slide projector having a first plane polarizing means for controlling the plane of polarization of light projected from said projection lens so that a slide supported in one or the other of said projecting stations may be selectively projected on a viewing screen by selectively changing the polarization orientation of said first polarizing means, the improvement in combination therewith comprising: means for plane polarizing the second portions of said first and second light beams 90* apart; means positioned to receive the second portions of said first and second light beams for previewing the images of slides supported at said first and second projecting stations; and second plane polarizing means positioned to control the plane of polarization of light received by said preview means, the polarization orientation of said second plane polarizing means being selectively changeable between one position whereat a slide supported in said first projecting station is previewed to another position whereat a slide supported in said second projecting station is previewed.

Claim 10

In a lap dissolve slide projector wherein slides in first and second projecting stations are, respectively, illuminated by first and second light beams, said first and second light beams being each divided into a first beam portion which is projected from said slide projector by a projection lens and a second beam portion which is not projected from said slide projector, the first portions of said first and second light beams being plane polarized 90* apart and said slide projector having a first plane polarizing means for controlling the plane of polarization of light projected from said projection lens so that a slide supported in one or the other of said projecting stations may be selectively projected on a viewing screen by selectively changing the polarization orientation of said first polarizing means, the improvement in combination therewith comprising: means for plane polarizing the second portions of said first and second light beams 90* apart; means positioned to receive the second portions of said first and second light beams for previewing the images of slides supported at said first and second projecting stations; and second plane polarizing means positioned to control the plane of polarization of light received by said preview means, the polarization orientation of said second plane polarizing means being selectively changeable between one position whereat a slide supported in said first projecting station is previewed to another position whereat a slide supported in said second projecting station is previewed.

Claim 11

The invention defined in claim 8, including means for simultaneously changing the polarization orientations of said first and second polarizing means, said second polarizing means being orientated with respect to said first polarizing means to transmit to said preview means the second portion of the one of said light beams not being projected so that the slide in the one of said projectinG stations which is not being projected is previewed.

Claim 12

A slide projector, comprising: means defining first and second projecting stations each for receiving and supporting a slide or the like to be projected; means for forming a first unpolarized visible illuminating light beam and a second unpolarized visible illuminating light beam, said light beam forming means being positioned to illuminate a slide supported at said first projecting station with said first illuminating beam and to illuminate a slide supported at said second projecting station with said second illuminating beam; polarizing beam splitter means having first and second light entrance paths and first and second light exit paths, said beam splitter means being operable. to direct visible light received along said first input path polarized in a determined plane of orientation out said first exit path and polarized in a plane 90* apart from said determined orientation out said second exit path, said beam splitter means further being operable to direct visible light received along said second input path plane polarized 90* apart from said determined orientation out said first exit path and plane polarized in said determined orientation out said second exit path; light directing means positioned with respect to said projecting stations and beam splitter means for directing said first illuminating beam as an input along said first entrance path and said second illuminating beam as an input along said second entrance path; projection lens means for projecting slide images on a selected viewing area, said projection lens means being positioned to receive and project output beams from said beam splitter first exit path; and means for plane polarizing light positioned to intercept the component of said first light beam made up of light polarized at said determined orientation and the component of said second light beam made up of light polarized 90* apart from said determined orientation, the polarization orientation of said plane polarizing means being changeable between alignment with said determined plane of polarization orientation and 90* out of alignment therewith whereby transition may be made on a selected viewing area from the projection of the image of a slide supported at one of said projecting stations to the image of a slide supported at the other by so changing the polarization orientation of said plane polarizing means.

Claim 13

A slide projector, comprising: means defining first and second projecting stations each for receiving and supporting a slide or the like to be projected; means for forming a first unpolarized visible illuminating light beam and a second unpolarized visible illuminating light beam, said light beam forming means being positioned to illuminate a slide supported at said first projecting station with said first illuminating beam and to illuminate a slide supported at said second projecting station with said second illuminating beam; polarizing beam splitter means having first and second light entrance paths and first and second light exit paths, said beam splitter means being operable. to direct visible light received along said first input path polarized in a determined plane of orientation out said first exit path and polarized in a plane 90* apart from said determined orientation out said second exit path, said beam splitter means further being operable to direct visible light received along said second input path plane polarized 90* apart from said determined orientation out said first exit path and plane polarized in said determined orientation out said second exit path; light directing means positioned with respect to said projecting stations and beam splitter means for directing said first illuminating beam as an input along said first entrance path and said second illuminating beam as an input along said second entrance path; projection lens means for projecting slide images on a selected viewing area, said projection lens means being positioned to receive and project output beams from said beam splitter first exit path; and means for plane polarizing light positioned to intercept the component of said first light beam made up of light polarized at said determined orientation and the component of said second light beam made up of light polarized 90* apart from said determined orientation, the polarization orientation of said plane polarizing means being changeable between alignment with said determined plane of polarization orientation and 90* out of alignment therewith whereby transition may be made on a selected viewing area from the projection of the image of a slide supported at one of said projecting stations to the image of a slide supported at the other by so changing the polarization orientation of said plane polarizing means.

Claim 14

The invention defined in claim 10, including: means for previewing the image of a slide to be projected, said preview means being positioned to receive output beams from said beam splitter second exit path and being operable to form the image of a slide supported in said first or second projecting station; and wherein: said means for plane polarizing light also intercepts the component of said first light beam made up of light polarized 90* apart from said determined orientation and the component of said second light beam made up of light polarized at said determined orientation whereby change of the polarization orientation of said plane polarizing means between alignment with said determined orientation and 90* out of alignment therewith causes the image of the one of the slides in said projecting stations not being projected to be previewed.

Claim 15

The invention defined in claim 11, wherein said polarizing beam splitter means is a compound prism made up of two prisms having flat base surfaces with a multilayer material of substantially uniform thickness interposed between said base surfaces and defines a selected Brewster''s angle for the visible light spectrum at the interfaces of said prisms and multilayer material.

Claim 16

The invention defined in claim 12 wherein: said polarizing beam splitter means defines a Brewster''s angle of approximately 45* for the visible light spectrum; and each of said entrance and exit paths intersect the plane defineD by said multilayer material at approximately a 45* angle.