Prescription Optical Visor for the M50 Air Purifying Respirator

Full facepiece air-purifying respirators (APRs) provide a critical safeguard for warfighters against chemical, biological, radiological, and nuclear (CBRN) threats. Additionally, most full facepiece APRs, such as the Avon Protection M50, currently provide prescription vision correction using a lens insert assembly that is mounted inside the respirator, close to the user’s eyes. While these lens inserts offer vision correction functionality to the respirator, their size and placement between the eyes and the M50 visor (i.e., the “primary lens” of the M50) requires an eye relief to the visor greater than approximately 30 mm. This large eye relief, and inability to reduce it without eliminating the prescription optical correction, negatively impacts compatibility of the M50 with external sighting systems. U.S. warfighters urgently need a full facepiece APR solution that includes prescription optical correction integrated into the visor itself. This would eliminate the need for the lens insert and thus enable a reduction in eye relief. Smaller eye relief would improve compatibility with external sighting systems as the sighting system could then be brought closer to the eye, thereby improving the warfighter’s effectiveness. Further, U.S. warfighters require such an APR visor with integrated prescription lenses to be made-to-order with specified diopter strengths available on either half of the lens. The ability to fully customize the optical prescription is critical in addressing each user’s specific needs such as anisometropia which requires a different prescription in each eye. The integrated visor must also be resistant to threat agents as required by the NIOSH Statement of Standard for CBRN Full Facepiece APR. Finally, durability and optical performance of the visor should be on par with or exceed that of existing military respirator materials and comply with the requirements set forth in MIL-STD 810G. To address this need, Holochip Corporation is developing the Prescription Optical Visor for the M50 Air Purifying Respirator (POV). The POV is a replacement visor for full facepiece APRs with an integrated left-eye/right-eye pair of thin, printable gradient index (GRIN) Fresnel lenses embedded in polyurethane (PU). The POV will support a different optical prescription for each eye with customizable made-to-order prescription strengths ranging from -10.00 to +8.00 Diopters. The POV will maintain the shape and size of the primary lens (i.e., the visor) of the Avon Protection M50 CBRN full facepiece APR. The PU encapsulation of the GRIN Fresnel lenses will provide the POV with threat agent permeation resistance characteristics required by the NIOSH Statement of Standard for Chemical, Biological, Radiological, and Nuclear (CBRN) Full Facepiece APR. Further, the optical clarity of cast PU and integrated one-piece design will provide the POV with durability and optical performance demanded by warfighters and required by MIL-STD 810G.