Update data.json

Added example "vanishing-point", and added "description" field in examples - "rochester-cloak" and "aplanatic-points".

gallery/data.json

@@ -160,6 +160,7 @@
           "Stas Fainer"
         ],
         "title": "Aplanatic points"
+        "description": "Aplanatic points of an optical system are special points on its optical axis, such that \"rays proceeding from one of them will all converge to, or seen to diverge from the other point\".<br><br>Ellipse: the two foci of the elliptical lens/mirror are aplanatic points, since light emitted from one focus will converge towards the other.<br><br>Sphere: a spherical lens has two aplanatic points, inside and outside the sphere - for more details see the simulation.<br><br>Hyperbola: the two foci of the <a href=\"https://phydemo.app/ray-optics/gallery/hyperbolic-mirror\" target=\"_blank\">Hyperbolic mirror</a> simulation are also aplanatic points.<br><br><br>Given two points with horizontal coordinates \\(x_1\\) and \\(x_2\\), and given the refractive index outside and inside our optical element as \\(n_1\\) and \\(n_2\\) (respectively), for this two points to be aplanatic points - the boundary of our optical element must fulfill the following equation:<br>\\(k_1 n_1 \\sqrt{ (x - x_1)^2 + y^2} + k_2 n_2 \\sqrt{  (x - x_2)^2 + y^2} = n_1 |x_1| + n_2 |x_2|\\)<br>such that \\(k_i=1\\) or \\(-1\\) if the ray connecting \\(x_i\\) and the boundary of our optical element is real or imaginary, respectively.<br>This is an equation of a Cartesian oval, of which the conic sections are special cases."
       }
     ]
   },
@@ -198,6 +199,14 @@
         ],
         "title": "Transverse and longitudinal magnification"
       },
+      {
+        "id": "vanishing-point",
+        "contributors": [
+          "Stas Fainer"
+        ],
+        "title": "Vanishing point"
+        "description": "Some optical systems map infinite parallel lines, to lines on the image plane which meet at a single point, making an illusion that the parallel lines meet \"at infinity\". This single point is called the vanishing point.<br><br> For an optical system comprising an ideal lens with focal length \\(f\\), located on the \\(XY\\) plane, such that it’s optical axis coincides with the \\(X\\)(horizontal) axis and the lens coincides with the \\(Y\\) axis, the vanishing point for a line with a slope \\(m\\), located at \\(x<0\\), is given by the \\((x,y)\\) coordinates \\((f,m f)\\) ."
+      },
       {
         "id": "monochromatic-aberrations",
         "contributors": [
@@ -291,6 +300,7 @@
           "Stas Fainer"
         ],
         "title": "Rochester cloak"
+        "description": "Rochester cloak is a type of cloaking device, which uses only 4 lenses. In the version presented in this simulation, the focal length of the two external lenses is \\(f_1\\), and of the two mid lenses is \\(f_2\\), such that the distance between consecutive lenses of focal lengths \\(f_1\\) and \\(f_2\\) equals \\(t_1=f_1+f_2\\), and the distance between the mid lenses is \\(t_2=2f_2\\frac{f1+f2}{f1-f2}\\)."
       }
     ]
   },