diff --git a/data/contributors.json b/data/contributors.json
index 93906e35..9e0a07c1 100644
--- a/data/contributors.json
+++ b/data/contributors.json
@@ -420,5 +420,12 @@
       ]
     },
     "firstCommit": "2025-01-21"
+  },
+  {
+    "name": "Leon Seidel",
+    "contributions": {
+      "gallery": true
+    },
+    "firstCommit": "2025-01-23"
   }
 ]
\ No newline at end of file
diff --git a/data/galleryList.json b/data/galleryList.json
index d0f78488..9a5be33b 100644
--- a/data/galleryList.json
+++ b/data/galleryList.json
@@ -286,6 +286,12 @@
         "contributors": [
           "Peter Becher"
         ]
+      },
+      {
+        "id": "koehler-illumination",
+        "contributors": [
+          "Leon Seidel"
+        ]
       }
     ]
   },
diff --git a/data/galleryScenes/koehler-illumination.json b/data/galleryScenes/koehler-illumination.json
new file mode 100644
index 00000000..0b0023ed
--- /dev/null
+++ b/data/galleryScenes/koehler-illumination.json
@@ -0,0 +1,357 @@
+{
+  "version": 5,
+  "objs": [
+    {
+      "type": "AngleSource",
+      "p1": {
+        "x": 260,
+        "y": 440
+      },
+      "p2": {
+        "x": 280,
+        "y": 440
+      }
+    },
+    {
+      "type": "AngleSource",
+      "p1": {
+        "x": 260,
+        "y": 480
+      },
+      "p2": {
+        "x": 280,
+        "y": 480
+      }
+    },
+    {
+      "type": "AngleSource",
+      "p1": {
+        "x": 260,
+        "y": 520
+      },
+      "p2": {
+        "x": 280,
+        "y": 520
+      }
+    },
+    {
+      "type": "IdealLens",
+      "p1": {
+        "x": 440,
+        "y": 260
+      },
+      "p2": {
+        "x": 440,
+        "y": 700
+      }
+    },
+    {
+      "type": "IdealLens",
+      "p1": {
+        "x": 765.25,
+        "y": 240
+      },
+      "p2": {
+        "x": 765.25,
+        "y": 720
+      }
+    },
+    {
+      "type": "IdealLens",
+      "p1": {
+        "x": 1060,
+        "y": 240
+      },
+      "p2": {
+        "x": 1060,
+        "y": 720
+      },
+      "focalLength": 195
+    },
+    {
+      "type": "IdealLens",
+      "p1": {
+        "x": 1353.5,
+        "y": 180
+      },
+      "p2": {
+        "x": 1353.5,
+        "y": 780
+      }
+    },
+    {
+      "type": "AngleSource",
+      "p1": {
+        "x": 260,
+        "y": 400
+      },
+      "p2": {
+        "x": 280,
+        "y": 400
+      }
+    },
+    {
+      "type": "AngleSource",
+      "p1": {
+        "x": 260,
+        "y": 560
+      },
+      "p2": {
+        "x": 280,
+        "y": 560
+      }
+    },
+    {
+      "type": "TextLabel",
+      "x": 381,
+      "y": 248,
+      "text": "{{collectorlens}}",
+      "font": "Times New Roman"
+    },
+    {
+      "type": "TextLabel",
+      "x": 726.5,
+      "y": 226.5,
+      "text": "{{fieldlens}}",
+      "font": "Times New Roman"
+    },
+    {
+      "type": "TextLabel",
+      "x": 656,
+      "y": 260,
+      "text": "{{aperture1changesinte}}",
+      "font": "Times New Roman",
+      "alignment": "center"
+    },
+    {
+      "type": "TextLabel",
+      "x": 942.75,
+      "y": 278.25,
+      "text": "{{aperture2changesfiel}}",
+      "font": "Times New Roman",
+      "alignment": "center"
+    },
+    {
+      "type": "TextLabel",
+      "x": 993.5,
+      "y": 226,
+      "text": "{{condensorlens}}",
+      "font": "Times New Roman"
+    },
+    {
+      "type": "TextLabel",
+      "x": 1290,
+      "y": 168,
+      "text": "{{objectivelens}}",
+      "font": "Times New Roman"
+    },
+    {
+      "type": "TextLabel",
+      "x": 1594.5,
+      "y": 480,
+      "text": "{{sampleisnowilluminat}}",
+      "font": "Times New Roman"
+    },
+    {
+      "type": "Aperture",
+      "p1": {
+        "x": 664.625,
+        "y": 360.25
+      },
+      "p2": {
+        "x": 664.625,
+        "y": 640.25
+      },
+      "p3": {
+        "x": 664.625,
+        "y": 360.5
+      },
+      "p4": {
+        "x": 664.625,
+        "y": 640
+      }
+    },
+    {
+      "type": "Aperture",
+      "p1": {
+        "x": 945.25,
+        "y": 340.125
+      },
+      "p2": {
+        "x": 945.25,
+        "y": 620.125
+      },
+      "p3": {
+        "x": 945.25,
+        "y": 433.75
+      },
+      "p4": {
+        "x": 945.25,
+        "y": 526.5
+      }
+    },
+    {
+      "type": "LineArrow",
+      "p1": {
+        "x": 664.75,
+        "y": 740
+      },
+      "p2": {
+        "x": 764.125,
+        "y": 740
+      },
+      "arrow": true,
+      "backArrow": true
+    },
+    {
+      "type": "LineArrow",
+      "p1": {
+        "x": 765.5,
+        "y": 740
+      },
+      "p2": {
+        "x": 866,
+        "y": 740
+      },
+      "arrow": true,
+      "backArrow": true
+    },
+    {
+      "type": "LineArrow",
+      "p1": {
+        "x": 868.25,
+        "y": 740
+      },
+      "p2": {
+        "x": 1059,
+        "y": 740
+      },
+      "arrow": true,
+      "backArrow": true
+    },
+    {
+      "type": "LineArrow",
+      "p1": {
+        "x": 1061,
+        "y": 740
+      },
+      "p2": {
+        "x": 1256.25,
+        "y": 740
+      },
+      "arrow": true,
+      "backArrow": true
+    },
+    {
+      "type": "TextLabel",
+      "x": 707,
+      "y": 771,
+      "text": "f₁"
+    },
+    {
+      "type": "TextLabel",
+      "x": 955.75,
+      "y": 771.5,
+      "text": "f₂"
+    },
+    {
+      "type": "TextLabel",
+      "x": 1153.625,
+      "y": 771.625,
+      "text": "f₂"
+    },
+    {
+      "type": "TextLabel",
+      "x": 811.125,
+      "y": 771.25,
+      "text": "f₁"
+    },
+    {
+      "type": "Detector",
+      "p1": {
+        "x": 1474.75,
+        "y": 440.625
+      },
+      "p2": {
+        "x": 1474.75,
+        "y": 520.625
+      },
+      "irradMap": true,
+      "binSize": 2.62
+    },
+    {
+      "type": "Aperture",
+      "p1": {
+        "x": 665.125,
+        "y": 327.5
+      },
+      "p2": {
+        "x": 665.125,
+        "y": 633
+      },
+      "p3": {
+        "x": 665.125,
+        "y": 367
+      },
+      "p4": {
+        "x": 665.125,
+        "y": 593.5
+      }
+    },
+    {
+      "type": "TextLabel",
+      "x": 236.5,
+      "y": 473.5,
+      "text": "{{spatiallyextendedand}}",
+      "alignment": "right"
+    },
+    {
+      "type": "TextLabel",
+      "x": 1463,
+      "y": 409.25,
+      "text": "{{sample}}",
+      "font": "Times New Roman"
+    },
+    {
+      "type": "Blocker",
+      "p1": {
+        "x": 1476,
+        "y": 421.75
+      },
+      "p2": {
+        "x": 1476,
+        "y": 541.75
+      }
+    },
+    {
+      "type": "CropBox",
+      "p1": {
+        "x": -230,
+        "y": 63
+      },
+      "p4": {
+        "x": 1977,
+        "y": 884
+      }
+    },
+    {
+      "type": "CropBox",
+      "p1": {
+        "x": 245,
+        "y": -185
+      },
+      "p4": {
+        "x": 1580,
+        "y": 1150
+      }
+    }
+  ],
+  "width": 1500,
+  "height": 800,
+  "rayModeDensity": 2.4833290030907684,
+  "origin": {
+    "x": 202.95520587050032,
+    "y": 171.61797271677003
+  },
+  "scale": 0.5252204436432255
+}
\ No newline at end of file
diff --git a/locales/en/gallery.json b/locales/en/gallery.json
index e9d5e3dd..e2c93569 100644
--- a/locales/en/gallery.json
+++ b/locales/en/gallery.json
@@ -318,6 +318,19 @@
       "title": "Pair of Axicons making a Rainbow Ring",
       "whitelightsource": "White\nLight\nSource"
     },
+    "koehlerIllumination": {
+      "title": "Köhler Illumination",
+      "description": "This setup, invented in 1893 by August Köhler, is very useful if you are dealing with any type of microscopy. It provides a homogeneous illumination on a sample, from any inhomogeneous light source. The image of the illumination source (e.g. lamp filament) is therefore not visible on the sample. The two apertures can be used to either change the intensity and numerical aperture (NA) or the field of view of your illumination. The second aperture is particularly advantageous, as you can close it to focus your sample. If the edges of the aperture are in focus, then the sample is focused too. It is also referred to as a 4f-setup, since it uses four focal lengths in distance.",
+      "collectorlens": "collector lens",
+      "fieldlens": "field lens",
+      "aperture1changesinte": "aperture 1\nchanges\nintensity, NA",
+      "aperture2changesfiel": "aperture 2\nchanges\nfield of view",
+      "condensorlens": "condensor lens",
+      "objectivelens": "objective lens",
+      "sampleisnowilluminat": "sample is now \nilluminated homogeneously",
+      "spatiallyextendedand": "spatially extended and\ninhomogeneous light source",
+      "sample": "sample"
+    },
     "parabolicMirror": {
       "description": "This simulation demonstrates the focusing property of the parabolic mirror.",
       "title": "Parabolic Mirror"
@@ -488,4 +501,4 @@
     "openInSimulator": "Open in Simulator",
     "title": "The Ray Optics Gallery"
   }
-}
+}
\ No newline at end of file
diff --git a/locales/zh-CN/gallery.json b/locales/zh-CN/gallery.json
index 5990621c..5ce4a83b 100644
--- a/locales/zh-CN/gallery.json
+++ b/locales/zh-CN/gallery.json
@@ -470,6 +470,19 @@
       "dragtomovethelens": "拖拽此处可移动透镜",
       "title": "变焦镜头",
       "zoom": "← 变焦 →"
+    },
+    "koehlerIllumination": {
+      "title": "科勒照明",
+      "aperture1changesinte": "光圈 1\n改变强度、NA",
+      "aperture2changesfiel": "光圈 2\n改变视野",
+      "sample": "样本",
+      "sampleisnowilluminat": "样本被\n均匀地照明",
+      "spatiallyextendedand": "空间上延展\n且不均匀的光源",
+      "objectivelens": "物镜",
+      "collectorlens": "集光透镜",
+      "condensorlens": "聚光镜",
+      "fieldlens": "场透镜",
+      "description": "这种设置由奥古斯特·克勒 (August Köhler) 于 1893 年发明，非常适合任何类型的显微镜使用。它可以从任何不均匀的光源提供样本的均匀照明，因此光源（例如灯丝）的影像不会出现在样本上。这两个光圈可以用来调节照明的强度和数值孔径（NA），或改变视野范围。第二个光圈特别有用，因为您可以关闭它来对焦样本。如果光圈的边缘清晰聚焦，那么样本也会处于聚焦状态。这种设置将四个焦距排列在一起，因此也被称为 4f 设置。"
     }
   },
   "galleryPage": {
diff --git a/locales/zh-TW/gallery.json b/locales/zh-TW/gallery.json
index 4d426454..64d7dbe8 100644
--- a/locales/zh-TW/gallery.json
+++ b/locales/zh-TW/gallery.json
@@ -470,6 +470,19 @@
       "dragtomovethelens": "拖曳此處可移動透鏡",
       "title": "變焦鏡頭",
       "zoom": "← 變焦 →"
+    },
+    "koehlerIllumination": {
+      "title": "科勒照明",
+      "aperture1changesinte": "光圈 1\n改變強度、NA",
+      "aperture2changesfiel": "光圈 2\n改變視野",
+      "sample": "樣本",
+      "sampleisnowilluminat": "樣本被\n均勻地照明",
+      "spatiallyextendedand": "空間上延展\n且不均勻的光源",
+      "objectivelens": "物鏡",
+      "collectorlens": "集光透鏡",
+      "condensorlens": "聚光鏡",
+      "fieldlens": "場透鏡",
+      "description": "這種設置由奧古斯特·克勒 (August Köhler) 於 1893 年發明，非常適合任何類型的顯微鏡使用。它可以從任何不均勻的光源提供樣本的均勻照明，因此光源（例如燈絲）的影像不會出現在樣本上。這兩個光圈可以用來調節照明的強度和數值孔徑（NA），或改變視野範圍。第二個光圈特別有用，因為您可以關閉它來對焦樣本。如果光圈的邊緣清晰聚焦，那麼樣本也會處於聚焦狀態。這種設置將四個焦距排列在一起，因此也被稱為 4f 設置。"
     }
   },
   "galleryPage": {