From 79404902163796977d21248fb047eb01ed981b4b Mon Sep 17 00:00:00 2001 From: Claude Meny Date: Sun, 6 Oct 2019 16:24:39 +0200 Subject: [PATCH] Update cheatsheet.en.md --- .../02.plane-refracting-surface-overview/cheatsheet.en.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/01.curriculum/01.physics-chemistry-biology/02.Niv2/04.optics/04.use-of-basic-optical-elements/01.plane-refracting-surface/02.plane-refracting-surface-overview/cheatsheet.en.md b/01.curriculum/01.physics-chemistry-biology/02.Niv2/04.optics/04.use-of-basic-optical-elements/01.plane-refracting-surface/02.plane-refracting-surface-overview/cheatsheet.en.md index 57c54c267..3fa90f525 100644 --- a/01.curriculum/01.physics-chemistry-biology/02.Niv2/04.optics/04.use-of-basic-optical-elements/01.plane-refracting-surface/02.plane-refracting-surface-overview/cheatsheet.en.md +++ b/01.curriculum/01.physics-chemistry-biology/02.Niv2/04.optics/04.use-of-basic-optical-elements/01.plane-refracting-surface/02.plane-refracting-surface-overview/cheatsheet.en.md @@ -104,8 +104,8 @@ defined, and therefore the spherical refracting surface becomes *quasi-stigmatic #### Gauss conditions / paraxial approximation and quasi-stigmatism When spherical refracting surfaces are used under the following conditions, named **Gauss conditions** :
-\- All *incident rays lie close to the optical axis*
\- The *angles of incidence and refraction are small*
+(the rays are slightly inclined on the optical axis, and intercept the spherical surface in the vicinity of its vertex)
Then *the spherical refracting surfaces* can be considered *quasi-stigmatic*, and therefore they can be used to build optical images. Mathematically, when an angle $`\alpha`$ is small $`\alpha < or \approx 10 ^\circ`$, the following approximations can be made :