Mirror is a smooth,highly polished surface covered a thin coating.Mirror is usually a thin coating of metal or dielectrics.    
VY Optics designs and manufactures a great choice of various high and partially reflecting mirrors for the spectral range:UV,visible,near infrared,and infrared regions.Metallic coatings are more broadband while dielectric coatings are more efficient. 
Selecting the proper mirror for your application requires making a number of choices.A few of the many considerations include:Reflectivity,Laser Damage Resistance, Coating Durability,Thermal Expansion of the substrate,Wavefront Distortion,Scattered Light,and certainly Cost. 

Specifications of our mirror as follow: 
*Material:BK7 A glass, Quartz, CaF2,crystals or others
*Clear Apenture:90%
*Squares/Rectangles:1mm to110mm+/-0.2mm 
*Center thickness tolerance:+/-0.1mm 
*Surface quality:60-40 to 20/10 Scratch/Dig
*Surface flatness:lambda/10 at 632.8nm
*Parallelism:1 Arc min