Applied optics.
3,843,835; 3,858,979; 3,858,981; 3,862,423; 3,884,552; 3,885,143; 3,890,034; 3,891,303; 3,934,153; 3,935,493; 3,937,942; 3,938,881; 3,939,347; 3,940,201; 3,941,923; 3,942,891; 3,944,323; 3,944,324; 3,944,337; 3,944,339; 3,944,341; 3,944,347; 3,944,730; 3,945,023; 3,945,025; 3,946,264; 3,947,094; 3,947,128; 3,947,717; 3,948,584; 3,949,223; 3,949,315; 3,949,318; 3,949,323; 3,950,082; 3,951,523; 3,952,311; 3,952,321; 3,952,323; 3,953,111; 3,953,112; 3,957,340; 3,958,864; 3,958,866; 3,960,442; 3,961,844; 3,961,845.