Fabrication method and use of F40 mm large-size and high-contrast

A method for preparing a Φ40 mm sized fiber optic image inverter, comprising the following steps:

• (1) mono fibers and light-absorbing glass fibers preparing:
• matching core glass rods with a high refractive index and cladding glass tubes with a low refractive index, followed by drawing to obtain mono fibers, wherein each of the mono fibers has a diameter of 3.20-4.20 mm;
• drawing light-absorbing glass into light-absorbing glass fibers, wherein each of the light-absorbing glass fibers has a diameter of 0.49-0.64 mm;
• (2) multi fiber assemblies drawing:
• arranging the mono fibers to form a mono fiber hexagonal prism with a hexagonal cross section, and inserting the light-absorbing glass fibers into gaps among the mono fibers drawn to obtain multi fiber assemblies, wherein in the mono fiber hexagonal prism, there are 4 mono fibers at each side of the hexagonal cross section of the mono fiber hexagonal prism with the total number of the mono fibers to be 37, and the number of the light-absorbing glass fibers inserted is 24-60;
• then drawing the multi fiber assemblies into multi fibers, wherein each of the multi fibers has a hexagonal cross section corresponding to that of the multi fiber assembly, and a distance between opposite sides of the hexagonal cross section of the multi fiber is 0.78-0.98 mm;
• (3) multi-multi assemblies drawing:
• arranging the multi fibers to form a multi fiber hexagonal prism with a hexagonal cross section to obtain multi-multi assemblies, wherein in the multi-multi assemblies arranged by the multi fibers, there are 17 multi fibers at each side of the hexagonal cross section of the multi fiber hexagonal prism with the total number of the multi fibers to be 817;
• then drawing the multi-multi assemblies into multi-multi fibers, wherein each of the multi-multi fibers has a hexagonal cross section corresponding to that of the multi-multi assembly, and a distance between opposite sides of the hexagonal cross section of the multi-multi fiber is 0.87-0.89 mm;
• and
• (4) heat press fusing and twisting:
• cutting the multi-multi fibers into a fixed length and arranging into a fiber assembly bundle, followed by subjecting to heat press fusion according to a designed compression ratio before and after heat press fusion of the fiber assembly bundle to obtain a fiber optic faceplate block of the Φ40 mm sized fiber optic image inverter with a fiber pitch of no more than 4.0 μm;
• then subjecting both ends of the fiber optic faceplate block to a twisting operation at an angle of 180° to obtain the Φ40 mm sized fiber optic image inverter with an effective area of more than Φ40 mm,
• wherein the light-absorbing glass consists of the following components in molar percentage:
• SiO2
• 60.0-69.9%
• Al2O3
• 1.0-10.0%
• B2O3
• 10.1-15.0%
• Na2O
• 1.0-8.0%
• K2O
• 3.0-10.0%
• MgO
• 0.1-1.0%
• CaO
• 0.5-5.0%
• ZnO
• 0-0.1%
• TiO2
• 0-0.1%
• ZrO2
• 0.1-1.0%
• Fe2O3
• 3.0-6.5%
• Co2O3
• 0.1-0.5%
• V2O5
• 0.51-1.5%
• MoO3
• 0.1-1.0%.
• the fiber optic image inverter has an optical crosstalk of less than 1.0% at 0.1 mm from a cutting edge;
• the fiber optic image inverter has a resolution of more than 140 lp/mm;
• the fiber optic image inverter has a light spectrum transmittance of more than 70% within a wavelength range of 400-700 nm.