APPLICATION OF SURFACE-RELIEF DIFFRACTIVE OPTICS TO HELMET MOUNTED DISPLAYS

RECENT ADVANCES IN BINARY OPTICS TECHNOLOGY STRONGLY SUGGEST THAT DIFFRACTIVE OPTICS MAY PROVIDE A REVOLUTIONARY SOLUTION TO THE PROBLEM OF DEVELOPING COMPACT, LIGHTWEIGHT OPTICAL ASSEMSLIES FOR HELMET MOUNTED DISPLAYS. SURFACE-RELIEF DIFFRACTIVE LENSES PROVIDE THE OPTICAL DESIGNER WITH ENOUGH DEGREES OF FREEDOM TO ELIMINATE, IN MANY CASES, THE THIRD-ORDER COMA, ASTIGMATISM, AND FIELD CURVATURE. FABRICATION TECHNIQUES ALSO EXIST TO "BLAZE" OR TAILOR THE PHASE PROFILE OF EACH ZONE; THIS PROVIDES A DIFFRACTIVE LENS THAT EXHIBITS HIGH DIFFRACTION EFFICIENCY, THAT IS, NEARLY ALL OF THE INCIDENT LIGHT GOES TO THE PRINCIPAL FOCUS. FOR MANY CASES OF PRACTICAL INTEREST, WE HAVE SHOWN THAT A SINGLE DIFFRACTIVE LENS ACTUALLY PERFORMS BETTER THAN CONVENTIONAL LENS SYSTEMS CONSISTING OF SEVERAL AIR-SPACED GLASS ELEMENTS. THE OBJECTIE OF THE PROPOSED RESEARCH IS TO DEMONSTRATE THE FEASIBILITY OF UTILIZING DIFFRACTIVE OPTICS TECHNOLOGY TO ANSWER HEAD-BORN WEIGHT AND CENTER OF GRAVITY CONSTRAINTS IN HELMET MOUNTED DISPLAY DESIGNS. WE PROPOSE TO IDENTIFY INNOVATIVE DESIGNS THAT EMPLOY SIMPLE COMBINERS AND A MINIMUM OF OPTICAL ELEMENTS WITHOUT SACRIFICING PERFORMANCE OR LIGHT EFFICIENCY. BOTH MONOCHROMATIC AND POLYCHROMATIC CONDITIONS WILL BE ADDRESSED. A SIGNIFICANT PORTION OF THE RESEARCH WILL BE CONCERNED WITH COLOR CORRECTION OF THE OPTICAL ASSEMBLY. ONE GOAL IS TO ELIMINATE THE NEED FOR A NOTCH FILTER ON THE CRT PHOSPHOR. THE EFFECTS ON THE SEE-THROUGH TRANSMISSION CHARACTERISTICS OF THE COMBINER WILL ALSO BE INVESTIGATED. THE MANUFACTURABILITY OF THE DIFFRACTIVE COMPONENTS INCLUDING THE COMBINER WILL BE STUDIED. A FIRST-ORDER TOLERANCE ANALYSIS WILL BE UNDERTAKEN FOR THE MOST PROMISING DESIGNS. PHASE II RESEARCH AND DEVELOPMENT WILL CONCENTRATE ON FABRICATING PROTOTYPES OF A DESIGN USEFUL TO THE DOD COMPONENT. IT IS EXPECTED THAT THE PHASE II DEVELOPMENT WILL LEAD TO FLYABLE HARDWARE EARLY IN PHASE III.