Projection system having low astigmatism

A projection system, comprising:

• a light source to generate light;
• conditioning optics to condition the light from the light source;
• a telecentric imaging core to impose an image on conditioned light from the conditioning optics to form image light, the imaging core including a polarizing beamsplitter and at least one imager, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index, and the astigmatism arises at least partly in the polarizing beamsplitter, at least one element in the imaging core adapted to reduce astigmatism in the image light;
• and
• a projection lens system to project the astigmatism-reduced image light from the imaging core.

An optical device, comprising:

• a polarizing beamsplitter, a first path being defined through the polarizing beamsplitter for light in a first polarization state, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index;
• at least one imager disposed to reflect light back to the polarizing beamsplitter, portions of light received by the at least one imager being polarization rotated, polarization rotated light propagating along a second path from the imager and through the polarizing beamsplitter;
• and
• an astigmatism compensating element disposed on the second path to reduce astigmatism in the polarization rotated light caused by the polarizing beamsplitter, the astigmatism compensating element comprising a plate of high index material having a refractive index higher than a refractive index of the covers, the plate of high index material being disposed between the polarization sensitive reflective film and one of the covers.

An optical device, comprising:

• a polarizing beamsplitter, a first path being defined through the polarizing beamsplitter for light in a first polarization state, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index;
• at least one imager disposed to reflect light back to the polarizing beamsplitter, portions of light received by the at least one imager being polarization rotated, polarization rotated light propagating along a second path from the imager and through the polarizing beamsplitter;
• a color separating prism disposed to receive light output from the polarizing beamsplitter along the first path, the at least one imager comprising multiple imagers disposed proximate respective color output faces of the color separating prism, the color separating prism including at least first and second color separating elements, the first color separating element being closer to the polarizing beamsplitter than at least the second color separating element, the first and second color separating elements being separated by a first gap layer of material having a refractive index lower than a refractive index of the color separating elements, a thickness of the gap layer being selected to reduce astigmatism arising in the polarizing beamsplitter.

An optical device, comprising:

• a polarizing beamsplitter, a first path being defined through the polarizing beamsplitter for light in a first polarization state, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index;
• at least one imager disposed to reflect light back to the polarizing beamsplitter, portions of light received by the at least one imager being polarization rotated, polarization rotated light propagating along a second path from the imager and through the polarizing beamsplitter;
• a color separating prism disposed to receive light output from the polarizing beamsplitter along the first path, the at least one imager comprising multiple imagers disposed proximate respective color output faces of the color separating prism;
• and
• a wedge prism disposed between the color separating prism and the polarizing beamsplitter, a third gap layer, between the wedge prism and the color separating prism, having a thickness selected to reduce astigmatism arising in the polarizing beamsplitter.

An optical device, comprising:

• a polarizing beamsplitter, a first path being defined through the polarizing beamsplitter for light in a first polarization state, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index;
• at least one imager disposed to reflect light back to the polarizing beamsplitter, portions of light received by the at least one imager being polarization rotated, polarization rotated light propagating along a second path from the imager and through the polarizing beamsplitter;
• and
• a color separating prism disposed to receive light output from the polarizing beamsplitter along the first path, the at least one imager comprising multiple imagers disposed proximate respective color output faces of the color separating prism, the color separating prism comprising at least first and second color separating elements, the first color separating element being closer to the polarizing beamsplitter than at least the second color separating element, and a plate formed from a first material having a refractive index higher than a refractive index of at least one of the first and second color separating elements, being disposed between the first and second color separating elements.

An optical device, comprising:

• a polarizing beamsplitter, a first path being defined through the polarizing beamsplitter for light in a first polarization state, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index;
• at least one imager disposed to reflect light back to the polarizing beamsplitter, portions of light received by the at least one imager being polarization rotated, polarization rotated light propagating along a second path from the imager and through the polarizing beamsplitter;
• and
• a color separating element for separating the light into at least two color bands and an x-cube combining light in the at least two color bands, at least a respective reflective polarizing beamsplitter and a respective imager disposed between the color separating element and the x-cube combiner for each of the at least two color bands, the x-cube combiner including astigmatism-reducing slabs of material having a refractive index different from a refractive index of x-cube prisms forming the x-cube.

An optical device, comprising:

• a polarizing beamsplitter, a first path being defined through the polarizing beamsplitter for light in a first polarization state, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index;
• at least one imager disposed to reflect light back to the polarizing beamsplitter, portions of light received by the at least one imager being polarization rotated, polarization rotated light propagating along a second path from the imager and through the polarizing beamsplitter;
• and
• a first film on the second path, the first film being disposed between first and second covers, the first and second covers having a refractive index higher than a refractive index of the first film, the first film reducing astigmatism in the polarization rotated light caused by the polarizing beamsplitter.

A projection system, comprising:

• a light source to generate light;
• conditioning optics to condition the light from the light source;
• an imaging core to impose an image on conditioned light from the conditioning optics to form image light, the imaging core including a polarizing beamsplitter and at least one imager, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index, and the astigmatism arises at least partly in the polarizing beamsplitter, the polarizing beamsplitter comprising a wedge disposed between the multilayer, polarization sensitive reflective film and one of the covers, the wedge having a refractive index less than the refractive index of the covers to reduce the astigmatism;
• and
• a projection lens system to project the astigmatism-reduced image light from the imaging core.

A projection system, comprising:

• a light source to generate light;
• conditioning optics to condition the light from the light source;
• an imaging core to impose an image on conditioned light from the conditioning optics to form image light, the imaging core including a polarizing beamsplitter and at least one imager, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index, and the astigmatism arises at least partly in the polarizing beamsplitter, the polarizing beamsplitter includes a plate disposed between the multilayer, polarization sensitive reflective film and one of the covers, the plate having a refractive index higher than the refractive index of the covers to reduce the astigmatism;
• and
• a projection lens system to project the astigmatism-reduced image light from the imaging core.

A projection system, comprising:

• a light source to generate light;
• conditioning optics to condition the light from the light source;
• an imaging core to impose an image on conditioned light from the conditioning optics to form image light, the imaging core including a polarizing beamsplitter and at least one imager, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index, and the astigmatism arises at least partly in the polarizing beamsplitter;
• a projection lens system to project image light from the imaging core;
• and
• an astigmatism-reducing cube disposed between the polarizing beamsplitter and the projection lens system, the astigmatism-reducing cube including a layer having a layer refractive index disposed between covers having a cover refractive index different from the layer refractive index, the layer being tilted relative to a propagation direction of the image light.

A projection system, comprising:

• a light source to generate light;
• conditioning optics to condition the light from the light source;
• an imaging core to impose an image on conditioned light from the conditioning optics to form image light, the imaging core including a polarizing beamsplitter and at least one imager, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index, and the astigmatism arises at least partly in the polarizing beamsplitter, at least one element in the imaging core adapted to reduce astigmatism in the image light;
• a color separator disposed between the polarization beamsplitter and the at least one imager, the color separator being a color separating prism having at least first and second color separating elements separated by a gap layer of material having a refractive index different from a refractive index of the first and second color separating elements, a thickness of the gap layer being selected to reduce astigmatism in the image light;
• and
• a projection lens system to project the image light from the imaging core.

A projection system, comprising:

• a light source to generate light;
• conditioning optics to condition the light from the light source;
• an imaging core to impose an image on conditioned light from the conditioning optics to form image light, the imaging core including a polarizing beamsplitter and at least two imagers, the polarizing beamsplitter including a multilayer, polarization sensitive reflective film having a relatively low refractive index and covers on either side of the polarization sensitive reflective film having a relatively high refractive index, and the astigmatism arises at least partly in the polarizing beamsplitter, and an x-cube to combine light from the at least two imagers in at least two color bands, the x-cube combiner including astigmatism-reducing slabs of material having a refractive index different from a refractive index of x-cube prisms forming the x-cube;
• and
• a projection lens system to project the astigmatism-reduced image light from the imaging core.