diff --git a/main.c b/main.c
index fa3ba32..9adb634 100644
--- a/main.c
+++ b/main.c
@@ -16,6 +16,8 @@ typedef struct {
     float lambda;
     float angleM1;
     Vector2 center;
+    bool gaz;
+    float nGaz;
 } Michelson;
 
 Color WavelengthToColor(float lambda) {
@@ -47,9 +49,9 @@ bool GuiButtonRepeat(Rectangle bounds, const char* text, bool shouldRepeat) {
     return clicked || held;
 }
 
+/*
 void DrawInterferenceViewCPU(Michelson *mic, Rectangle rec) {
     DrawRectangleRec((Rectangle){rec.x - 4, rec.y - 30, rec.width + 8, rec.height + 34}, COLOR_PANEL);
-    //DrawText("ECRAN", rec.x, rec.y - 30, 20, WHITE);
     DrawText("ECRAN", rec.x, rec.y - 26, 20, COLOR_TEXT_DIM);
 
     DrawRectangleRec(rec, BLACK);
@@ -57,8 +59,14 @@ void DrawInterferenceViewCPU(Michelson *mic, Rectangle rec) {
     
     Color baseColor = WavelengthToColor(mic->lambda);
    
+    float extraPath = 0.0f;
+    if (mic->gaz)
+        extraPath = 2.0f * 100.0f * (mic->nGaz - 1.0f);
+
+    float d2_effective = mic->d2 + (extraPath / 2.0f);
+
     // Diff de marche du à l'axe (2 * e) + micro -> nano
-    float deltaLnm = 2.0f * (mic->d1 - mic->d2) * 1000.0f; 
+    float deltaLnm = 2.0f * (mic->d1 - d2_effective) * 1000.0f; 
     
     int cx = rec.x + rec.width / 2;
     int cy = rec.y + rec.height / 2;
@@ -98,6 +106,7 @@ void DrawInterferenceViewCPU(Michelson *mic, Rectangle rec) {
     DrawLine(cx - 10, cy, cx + 10, cy, Fade(WHITE, 0.5f));
     DrawLine(cx, cy - 10, cx, cy + 10, Fade(WHITE, 0.5f));
 }
+*/
 
 void DrawInterferenceViewGPU(Michelson *mic, Rectangle rec, Shader shader, bool *isFullscreen) {
     
@@ -119,12 +128,17 @@ void DrawInterferenceViewGPU(Michelson *mic, Rectangle rec, Shader shader, bool
     float scrHeight = (float)GetScreenHeight();
     float zoom = *isFullscreen ? 0.7 : 1; 
 
-    //
+    float addedOpticalPathOneWay = 0.0f;
+    if (mic->gaz) {
+        addedOpticalPathOneWay = 100.0f * (mic->nGaz - 1.0f);
+    }
+    float d2_effective = mic->d2 + addedOpticalPathOneWay;
+    
     SetShaderValue(shader, GetShaderLocation(shader, "center"), center, SHADER_UNIFORM_VEC2);
     SetShaderValue(shader, GetShaderLocation(shader, "screenHeight"), &scrHeight, SHADER_UNIFORM_FLOAT);
     
     SetShaderValue(shader, GetShaderLocation(shader, "d1"), &mic->d1, SHADER_UNIFORM_FLOAT);
-    SetShaderValue(shader, GetShaderLocation(shader, "d2"), &mic->d2, SHADER_UNIFORM_FLOAT);
+    SetShaderValue(shader, GetShaderLocation(shader, "d2"), &d2_effective, SHADER_UNIFORM_FLOAT);
     SetShaderValue(shader, GetShaderLocation(shader, "lambda"), &mic->lambda, SHADER_UNIFORM_FLOAT);
     SetShaderValue(shader, GetShaderLocation(shader, "angleM1"), &mic->angleM1, SHADER_UNIFORM_FLOAT);
     SetShaderValue(shader, GetShaderLocation(shader, "zoom"), &zoom, SHADER_UNIFORM_FLOAT);
@@ -183,6 +197,18 @@ void DrawMichelsonSchema (Michelson *mic) {
     DrawRectangleLines(startSource.x - 30, startSource.y - 20, 30, 40, GRAY);
     DrawText("Source", startSource.x - 50, startSource.y - 50, 20, LIGHTGRAY);
 
+    if (mic->gaz) {
+        float cellDist = 80.0f;
+        float cellW = 60.0f;
+        float cellH = 40.0f;
+        Rectangle cellRect = {c.x + cellDist, c.y - cellH / 2, cellW, cellH};
+        
+        DrawRectangleRec(cellRect, Fade(BLUE, 0.15f + (mic->nGaz - 1.0f) * 2.0f));
+        DrawRectangleLinesEx(cellRect, 2, SKYBLUE);
+        
+        DrawText(TextFormat("n=%.3f", mic->nGaz), c.x + cellDist, c.y + 25, 10, SKYBLUE);
+    }
+
     // M2
     DrawRectangle(posM2.x, posM2.y - (mirrorSize / 2), 12, mirrorSize, LIGHTGRAY);
     DrawRectangle(posM2.x, posM2.y - (mirrorSize / 2) + 2, 4, mirrorSize - 4, WHITE);
@@ -269,27 +295,40 @@ void DrawControlPanel(Michelson *mic) {
     // Angle M1
     startY += 90;
     DrawText(TextFormat("Inclinaison M1: %.3f deg", mic->angleM1), startX, startY, 20, ORANGE);
-    
     float stepAngle = speedMode ? 0.05f : 0.001f;
-
     if (GuiButtonRepeat((Rectangle){startX, startY + 30, btnSize, 25}, "-", shouldRepeat)) mic->angleM1 -= stepAngle;
     GuiSlider((Rectangle){startX + btnSize + 5, startY + 30, sliderWidth - 75, 25}, 0, 0, &mic->angleM1, -1.0f, 1.0f);
     if (GuiButtonRepeat((Rectangle){startX + btnSize + sliderWidth - 65, startY + 30, btnSize, 25}, "+", shouldRepeat)) mic->angleM1 += stepAngle;
     if (GuiButton((Rectangle){startX + contentWidth - 60, startY + 30, 60, 25}, "Zero")) mic->angleM1 = 0.0f;
-    
-    
+
     // Status 
+    startY += 70;
     bool isLameAir = (fabs(mic->angleM1) < 0.001f);
-    const char* modeTxt = isLameAir ? "MODE: LAME D'AIR" : "MODE: COIN D'AIR";
+    const char* modeTxt = isLameAir ? "LAME D'AIR" : "COIN D'AIR";
     Color modeColor = isLameAir ? SKYBLUE : GREEN;
-    
-    DrawRectangle(startX, startY + 70, contentWidth, 30, Fade(modeColor, 0.2f));
-    DrawRectangleLines(startX, startY + 70, contentWidth, 30, modeColor);
-    DrawText(modeTxt, startX + 10, startY + 78, 18, modeColor);
+
+    DrawRectangle(startX, startY, contentWidth, 30, Fade(modeColor, 0.2f));
+    DrawRectangleLines(startX, startY, contentWidth, 30, modeColor);
+    DrawText(modeTxt, startX + 10, startY + 8, 20, modeColor);
+
+    // Cuve de gaz
+    startY += 50;
+    DrawLine(startX, startY - 10, startX + contentWidth, startY - 10, Fade(GRAY, 0.3f));
+    DrawText("Cuve de Gaz (Indice n)", startX, startY, 20, SKYBLUE);
+    GuiCheckBox((Rectangle){startX, startY + 30, 20, 20}, "Cuve", &mic->gaz);
+    if (mic->gaz) {
+        DrawText(TextFormat("n = %.4f", mic->nGaz), startX + 150, startY + 30, 20, WHITE);
+        float stepN = speedMode ? 0.001f : 0.0001f;
+        if (GuiButtonRepeat((Rectangle){startX, startY + 55, btnSize, 25}, "-", shouldRepeat)) mic->nGaz -= stepN;
+        GuiSlider((Rectangle){startX + btnSize + 5, startY + 55, sliderWidth - 10, 25}, NULL, NULL, &mic->nGaz, 1.000f, 1.100f);
+        if (GuiButtonRepeat((Rectangle){startX + btnSize + sliderWidth, startY + 55, btnSize, 25}, "+", shouldRepeat)) mic->nGaz += stepN;
+        if (mic->nGaz < 1.0f) mic->nGaz = 1.0f;
+        //startY += 90; 
+    }
 
     // Données 
-    startY += 150;
-    DrawLine(startX, startY - 20, startX + contentWidth, startY - 20, GRAY);
+    startY += 100;
+    DrawLine(startX, startY - 10, startX + contentWidth, startY - 10, GRAY);
     DrawText("DONNEES TEMPS REEL", startX, startY, 20, GRAY);
     
     float delta = 2 * (mic->d1 - mic->d2);
diff --git a/michelson b/michelson
index 537eb3b..1d80071 100755
Binary files a/michelson and b/michelson differ