{
  "format": "krakenos.lens_drawing_properties.v1",
  "version": 1,
  "surfaces": [
    {
      "surface_index": 1,
      "label": "1",
      "surface": "Standard",
      "name": "E1 front crown",
      "material": "N-BK7",
      "properties": {
        "clear_aperture_mm": 26.0,
        "radius_tolerance": "+/-0.035",
        "thickness_tolerance": "+/-0.05",
        "diameter_tolerance": "+0/-0.03",
        "form_error": "3/ 3 (0.5) lambda=632.8 nm",
        "irregularity": "4/ -",
        "scratch_dig": "5/ 40-20",
        "surface_note": "6/ -",
        "coating_note": "R(avg) < 0.75% from 450-650 nm",
        "material_note": "Melt data required",
        "centration_note": "14/ 1'",
        "edge_note": "0.2 mm protective chamfer"
      }
    },
    {
      "surface_index": 2,
      "label": "2",
      "surface": "Standard",
      "name": "E1/E2 cement interface",
      "material": "N-SF5",
      "properties": {
        "clear_aperture_mm": 25.5,
        "radius_tolerance": "+/-0.025",
        "form_error": "3/ 3 (0.5) lambda=632.8 nm",
        "scratch_dig": "5/ 40-20",
        "cement_note": "NOA 61 or equivalent",
        "coating_note": "No coating on cemented surface",
        "material_note": "High-index flint element"
      }
    },
    {
      "surface_index": 3,
      "label": "3",
      "surface": "Standard",
      "name": "E2/E3 cement interface",
      "material": "N-LAK22",
      "properties": {
        "clear_aperture_mm": 25.0,
        "radius_tolerance": "+/-0.030",
        "thickness_tolerance": "+/-0.05",
        "form_error": "3/ 3 (0.5) lambda=632.8 nm",
        "scratch_dig": "5/ 40-20",
        "cement_note": "NOA 61 or equivalent",
        "material_note": "Lanthanum crown element"
      }
    },
    {
      "surface_index": 4,
      "label": "4",
      "surface": "Standard",
      "name": "E3 rear surface",
      "material": "AIR",
      "properties": {
        "clear_aperture_mm": 24.5,
        "radius_tolerance": "+/-0.040",
        "diameter_tolerance": "+0/-0.03",
        "form_error": "3/ 3 (0.5) lambda=632.8 nm",
        "irregularity": "4/ -",
        "scratch_dig": "5/ 40-20",
        "coating_note": "R(avg) < 0.75% from 450-650 nm",
        "edge_note": "Edge blacken after coating",
        "other_requirement": "Inspect cement wedge after assembly"
      }
    }
  ]
}