MWIR polarizing beamsplitter cube and method of making the same

A method of fabricating an infrared beamsplitter from first and second prismatic elements, comprising the steps of:

• applying a polarization coating to the first prismatic element;
• placing a liquid coating on one of said polarization coating and said second prismatic element, including forming said liquid coating with a refractive index range between 1.705 to 1.800 and with a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared, said thickness being less than 600 nm;
• placing said second prismatic element over said first prismatic element so that said liquid coating is contained between said polarization coating and said second prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to beamsplit infrared;
• and
• sealing the edges of said assembly to maintain said liquid coating between said first prismatic element and said second prismatic element,
• wherein said step of applying a polarization coating further includes applying an adhesion layer between said second prismatic element and said polarization coating to increase adhesion of the polarization coating to the first prismatic element, and
• wherein said adhesion layer comprises chromium and thorium fluoride.

A method of fabricating an infrared beamsplitter from first and second prismatic elements, comprising the steps of:

• applying a polarization coating to the first prismatic element;
• placing a liquid coating on one of said polarization coating and said second prismatic element;
• placing said second prismatic element over said first prismatic element so that said liquid coating is contained between said polarization coating and said second prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to beamsplit infrared;
• and
• sealing the edges of said assembly to maintain said liquid coating between said first prismatic element and said second prismatic element,
• wherein said liquid coating is a refractive index liquid having a refractive index range between 1.705 to 1.800 and a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared, said thickness being less than 600 nm.

A method of fabricating an infrared beamsplitter from first and second prismatic elements, comprising the steps of:

• applying a polarization coating to the first prismatic element;
• placing a liquid coating on one of said polarization coating and said second prismatic element;
• forming said liquid coating with a refractive index range between 1.705 to 1.800 and with a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared, said thickness being less than 600 nm;
• placing said second prismatic element over said first prismatic element so that said liquid coating is contained between said polarization coating and said second prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to beamsplit infrared;
• and
• sealing the edges of said assembly to maintain said liquid coating between said first prismatic element and said second prismatic element,
• wherein said step of applying a polarization coating further includes applying an adhesion layer between said second prismatic element and said polarization coating to increase adhesion of the polarization coating to the first prismatic element, and
• wherein said adhesion layer includes chromium and thorium fluoride.

An infrared beamsplitter comprising:

• a first prismatic element having a surface;
• a polarization coating on said surface of said first prismatic element;
• a second prismatic element having a surface aligned with said surface of said first prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to beamsplit infrared;
• a refractive index liquid layer occupying space between said surface of said first prismatic element and said surface of said second prismatic element said refractive index liquid layer having a refractive index range between 1.705 to 1.800 and a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared, said thickness being less than 600 nm;
• and
• a seal maintaining said refractive index liquid layer between said first prismatic element and said second prismatic element.

An infrared beamsplitter comprising:

• a first prismatic element having a surface;
• a polarization coating on said surface of said first prismatic element;
• a second prismatic element having a surface aligned with said surface of said first prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to bean split infrared:,
• a liquid coating occupying space between said surface of said first prismatic element and said surface of said second prismatic element;
• and
• a seal maintaining said liquid coating between said first prismatic element and said second prismatic element,
• wherein said liquid coating is a refractive index liquid having a refractive index range between 1.705 to 1.800 and a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared, said thickness being less than 600 nm.

An infrared beamsplitter comprising:

• a first prismatic element having a surface;
• a polarization coating on said surface of said first prismatic element;
• a second prismatic element having a surface aligned with said surface of said first prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to beamsplit infrared;
• a liquid coating occupying space between said surface of said first prismatic element and said surface of said second prismatic element said refractive index liquid layer having a refractive index range between 1.705 to 1.800 and a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared, said thickness being less than 600 nm;
• and
• a seal maintaining said liquid coating between said first prismatic element and said second prismatic element,
• wherein said seal is a urethane adhesive seal compatible with said refractive index liquid.

An infrared beamsplitter comprising:

• a first prismatic element having a surface;
• a polarization coating on said surface of said first prismatic element;
• a second prismatic element having a surface aligned with said surface of said first prismatic element, wherein said first and second prismatic elements have matching refractive indexes so as to beamsplit infrared;
• an adhesion layer between said first prismatic element and said polarization coating for increasing adhesion of said first prismatic element and said polarization coating;
• a liquid coating occupying space between said surface of said first prismatic element and said surface of said second prismatic element said refractive index liquid layer having a refractive index range between 1.705 to 1.800 and a thickness in combination with the flatness of said polarization coating and the viscosity of said refractive index liquid layer so as to beamsplit infrared said thickness being less than 600 nm;
• and
• a seal maintaining said liquid coating between said first prismatic element and said second prismatic element.