public void GetLightDataInFamilyDocument(Document familyDoc)
{
    // LightFamily API should work only in light fixture family document.
    if (familyDoc.OwnerFamily.FamilyCategory.BuiltInCategory == BuiltInCategory.OST_LightingFixtures)
        return;

    // Get the light family from the static method.
    LightFamily lightFamily = LightFamily.GetLightFamily(familyDoc);

    // Get the light source shape style and distribution style
    LightShapeStyle shapeStyle = lightFamily.GetLightShapeStyle();
    LightDistributionStyle distributionStyle = lightFamily.GetLightDistributionStyle();

    // Get the light photometric for each family type
    for (int index = 0; index < lightFamily.GetNumberOfLightTypes(); index++)
    {
        string typeName = lightFamily.GetLightTypeName(index);  // the type name
        LightType lightData = lightFamily.GetLightType(index);  // the light data for each type
        // How to get and set data in LightType object, please read help document for LightType class.
    }
}

Public Sub GetLightDataInFamilyDocument(familyDoc As Document)
   ' LightFamily API should work only in light fixture family document.
   If familyDoc.OwnerFamily.FamilyCategory.BuiltInCategory = BuiltInCategory.OST_LightingFixtures Then
      Return
   End If

   ' Get the light family from the static method.
   Dim lightFamily__1 As LightFamily = LightFamily.GetLightFamily(familyDoc)

   ' Get the light source shape style and distribution style
   Dim shapeStyle As LightShapeStyle = lightFamily__1.GetLightShapeStyle()
   Dim distributionStyle As LightDistributionStyle = lightFamily__1.GetLightDistributionStyle()

   ' Get the light photometric for each family type
   For index As Integer = 0 To lightFamily__1.GetNumberOfLightTypes() - 1
      Dim typeName As String = lightFamily__1.GetLightTypeName(index)
      ' the type name
      ' the light data for each type
      ' How to get and set data in LightType object, please read help document for LightType class.
      Dim lightData As LightType = lightFamily__1.GetLightType(index)
   Next
End Sub