Je viens d'acheter un nouveau miroir pour ma salle de bain mais je remarque que mon reflet est déformé. Je me trouve plus gros que je ne suis vraiment. Est-ce que tous les miroirs peuvent déformer l'image ? Comment savoir si un miroir est plat et donne une image correcte ?
A mirror, also known as a looking glass, is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminium are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very hard surface.

A mirror is a wave reflector. Light consists of waves, and when light waves reflect from the flat surface of a mirror, those waves retain the same degree of curvature and vergence, in an equal yet opposite direction, as the original waves. This allows the waves to form an image when they are focused through a lens, just as if the waves had originated from the direction of the mirror. The light can also be pictured as rays (imaginary lines radiating from the light source, that are always perpendicular to the waves). These rays are reflected at an equal yet opposite angle from which they strike the mirror (incident light). This property, called specular reflection, distinguishes a mirror from objects that diffuse light, breaking up the wave and scattering it in many directions (such as flat-white paint). Thus, a mirror can be any surface in which the texture or roughness of the surface is smaller (smoother) than the wavelength of the waves.

When looking at a mirror, one will see a mirror image or reflected image of objects in the environment, formed by light emitted or scattered by them and reflected by the mirror towards one's eyes. This effect gives the illusion that those objects are behind the mirror, or (sometimes) in front of it. When the surface is not flat, a mirror may behave like a reflecting lens. A plane mirror yields a real-looking undistorted image, while a curved mirror may distort, magnify, or reduce the image in various ways, while keeping the lines, contrast, sharpness, colors, and other image properties intact.

A mirror is commonly used for inspecting oneself, such as during personal grooming; hence the old-fashioned name "looking glass". This use, which dates from prehistory, overlaps with uses in decoration and architecture. Mirrors are also used to view other items that are not directly visible because of obstructions; examples include rear-view mirrors in vehicles, security mirrors in or around buildings, and dentist's mirrors. Mirrors are also used in optical and scientific apparatus such as telescopes, lasers, cameras, periscopes, and industrial machinery.

According to superstitions breaking a mirror is said to bring seven years of bad luck.

The terms "mirror" and "reflector" can be used for objects that reflect any other types of waves. An acoustic mirror reflects sound waves. Objects such as walls, ceilings, or natural rock-formations may produce echos, and this tendency often becomes a problem in acoustical engineering when designing houses, auditoriums, or recording studios. Acoustic mirrors may be used for applications such as parabolic microphones, atmospheric studies, sonar, and seafloor mapping. An atomic mirror reflects matter waves and can be used for atomic interferometry and atomic holography.
Un miroir courbé est un miroir dont la surface réfléchissante est incurvée. Cette surface peut être soit convexe, soit concave. La plupart des miroirs courbés ont des surfaces façonnées comme une partie d'une sphère, mais d'autres formes sont parfois utilisées dans les dispositifs optiques. Le type non sphérique le plus courant est le réflecteur parabolique, que l'on retrouve dans les dispositifs optiques tels que les télescopes réflecteurs qui doivent imager des objets lointains, car les systèmes de miroirs sphériques, comme les lentilles sphériques, souffrent d'aberration sphérique. Les miroirs déformants sont utilisés pour le divertissement. Ils présentent des régions convexes et concaves qui produisent des images déformées de manière délibérée. Ils fournissent également des images très agrandies ou très réduites (plus petites) lorsque l'objet est placé à certaines distances.
### Query ###
Je viens d'acheter un nouveau miroir pour ma salle de bain mais je remarque que mon reflet est déformé. Je me trouve plus gros que je ne suis vraiment. Est-ce que tous les miroirs peuvent déformer l'image ? Comment savoir si un miroir est plat et donne une image correcte ?

### Main Text ###
A mirror, also known as a looking glass, is an object that reflects an image. Light that bounces off a mirror will show an image of whatever is in front of it, when focused through the lens of the eye or a camera. Mirrors reverse the direction of the image in an equal yet opposite angle from which the light shines upon it. This allows the viewer to see themselves or objects behind them, or even objects that are at an angle from them but out of their field of view, such as around a corner. Natural mirrors have existed since prehistoric times, such as the surface of water, but people have been manufacturing mirrors out of a variety of materials for thousands of years, like stone, metals, and glass. In modern mirrors, metals like silver or aluminium are often used due to their high reflectivity, applied as a thin coating on glass because of its naturally smooth and very hard surface.

A mirror is a wave reflector. Light consists of waves, and when light waves reflect from the flat surface of a mirror, those waves retain the same degree of curvature and vergence, in an equal yet opposite direction, as the original waves. This allows the waves to form an image when they are focused through a lens, just as if the waves had originated from the direction of the mirror. The light can also be pictured as rays (imaginary lines radiating from the light source, that are always perpendicular to the waves). These rays are reflected at an equal yet opposite angle from which they strike the mirror (incident light). This property, called specular reflection, distinguishes a mirror from objects that diffuse light, breaking up the wave and scattering it in many directions (such as flat-white paint). Thus, a mirror can be any surface in which the texture or roughness of the surface is smaller (smoother) than the wavelength of the waves.

When looking at a mirror, one will see a mirror image or reflected image of objects in the environment, formed by light emitted or scattered by them and reflected by the mirror towards one's eyes. This effect gives the illusion that those objects are behind the mirror, or (sometimes) in front of it. When the surface is not flat, a mirror may behave like a reflecting lens. A plane mirror yields a real-looking undistorted image, while a curved mirror may distort, magnify, or reduce the image in various ways, while keeping the lines, contrast, sharpness, colors, and other image properties intact.

A mirror is commonly used for inspecting oneself, such as during personal grooming; hence the old-fashioned name "looking glass". This use, which dates from prehistory, overlaps with uses in decoration and architecture. Mirrors are also used to view other items that are not directly visible because of obstructions; examples include rear-view mirrors in vehicles, security mirrors in or around buildings, and dentist's mirrors. Mirrors are also used in optical and scientific apparatus such as telescopes, lasers, cameras, periscopes, and industrial machinery.

According to superstitions breaking a mirror is said to bring seven years of bad luck.

The terms "mirror" and "reflector" can be used for objects that reflect any other types of waves. An acoustic mirror reflects sound waves. Objects such as walls, ceilings, or natural rock-formations may produce echos, and this tendency often becomes a problem in acoustical engineering when designing houses, auditoriums, or recording studios. Acoustic mirrors may be used for applications such as parabolic microphones, atmospheric studies, sonar, and seafloor mapping. An atomic mirror reflects matter waves and can be used for atomic interferometry and atomic holography.

### Supplementary Text ###
Un miroir courbé est un miroir dont la surface réfléchissante est incurvée. Cette surface peut être soit convexe, soit concave. La plupart des miroirs courbés ont des surfaces façonnées comme une partie d'une sphère, mais d'autres formes sont parfois utilisées dans les dispositifs optiques. Le type non sphérique le plus courant est le réflecteur parabolique, que l'on retrouve dans les dispositifs optiques tels que les télescopes réflecteurs qui doivent imager des objets lointains, car les systèmes de miroirs sphériques, comme les lentilles sphériques, souffrent d'aberration sphérique. Les miroirs déformants sont utilisés pour le divertissement. Ils présentent des régions convexes et concaves qui produisent des images déformées de manière délibérée. Ils fournissent également des images très agrandies ou très réduites (plus petites) lorsque l'objet est placé à certaines distances.

### Draft ###

### 1. Query Decomposition

User states: "nouveau miroir... déformé... me trouve plus gros"
→ New bathroom mirror, distorted reflection, appears larger than reality

Key semantic: "plat" = flat/planar. User wants confirmation of basic optical principle.

Simple information retrieval. ● High confidence domain.

### 2. Optical Physics Foundation

Flat mirrors: specular reflection only
- Angle of incidence = angle of reflection
- Light rays preserve direction, only reverse propagation
- Normal image formation when object in front of mirror plane

Distortion sources:
- Surface curvature (convex/concave)  
- Angular positioning errors
- Manufacturing defects in glass surface

### 3. Mirror Analysis

True distortion mechanisms:
1. **Curvature-induced**: spherical/parabolic deviations from flat
2. **Installation angle**: tilted surfaces create perspective distortion
3. **Surface roughness**: micro-scale texture scattering light

User's "bigger reflection" → likely installation angle issue or minor surface texture.

### 4. Verification Methods

Quick tests for flatness:
- Straight edge visual alignment
- Level tool confirmation
- Grid pattern distortion check
- Ruler-based measurements from various angles

◐ Partial solution: basic visual inspection sufficient for most cases.

### 5. Manufacturing Reality

Modern mirrors: precision-ground glass with silver/aluminum backing
- Mass production standards typically high
- Defective units possible but rare
- Installation issues more common than manufacturing defects

∴ User likely has installation/positioning problem rather than defective mirror.

### 6. Response Structure

Address directly: oui, tous les miroirs peuvent déformer
→ Explain flat mirror principle  
→ Distinguish from curved mirrors (entertainment mirrors)
→ Practical test methods
→ Reassurance about manufacturing quality
→ Installation focus rather than replacement

Concise, authoritative, practical. ● High confidence in optical principles. Some uncertainty in specific user situation, but framework solid.

### Answer###
Oui, tous les miroirs peuvent théoriquement déformer l'image, mais cela dépend du type de miroir et de sa qualité de fabrication.

Les miroirs véritables et corrects sont ceux qui ont une surface plane et réfléchissante uniforme. Ces miroirs, comme les miroirs plans conventionnels, produisent des images réalistes et non déformées lorsque l'objet observé se trouve directement en face d'eux. Ils respectent le principe de réflexion spéculaire, où les rayons lumineux se réfléchissent selon des angles égaux mais opposés à l'angle d'incidence, formant ainsi une image claire et naturelle.

Les miroirs courbés, qu'ils soient convexes ou concaves, sont spécifiquement conçus pour déformer les images. Ils peuvent magnifier, réduire ou altérer l'image de manière variée selon la courbure de leur surface et la distance de l'objet observé. Ces miroirs déformants sont souvent utilisés à des fins de divertissement ou d'amusement.

Pour vérifier si votre miroir est effectivement plat et produit une image correcte, vous pouvez observer s'il reflète votre image de manière naturelle et proportionnelle. Un miroir défectueux ou mal installé pourrait présenter des distorsions dues à une courbure légère de la surface, à une mauvaise orientation, ou à des imperfections dans le traitement réfléchissant.

Les miroirs modernes utilisent généralement des revêtements métalliques comme l'argent ou l'aluminium appliqués sur du verre pour leur surface réfléchissante, ce qui assure normalement une grande qualité de réflexion lorsqu'ils sont correctement fabriqués.