Mirrors for CO₂ lasers

Coated copper and silicon substrates are mainly used as mirrors in CO₂ lasers. Additional materials such as molybdenum and aluminum are also available.

One of the quality features of bending mirrors is a small scattering loss combined with a long life expectancy. With our special production technology we can offer the highest quality products. The metal mirrors are normally nickel-plated, which prevents contamination with laser gas or coolant. The galvanic coating increases the damage threshold up to 40 kW (cw) at a Ø of 10 mm for gold-plated copper mirrors.

Copper mirrors are used when and where particularly high power levels produce heat in mirror substrates. Copper has the ability to conduct heat very well and exhibits better mechanical stability than other substrate materials when heat is adequately dissipated.

The mirrors are available with the folllowing types of coatings: hard gold coating, dielectric coating.

All copper mirrors of ample thickness are available with feedthroughs for water cooling.

The following are available:

• Radii from 8 mm to 60 m (concave/convex)
• Diameter from 5 mm to 150 mm
• Round/rectangular/cylindrical shapes
• Mirrors with water cooling (minimum thickness required)
• Atypical dimensions and shapes can be produced upon request

Specifications:

• Diameter: + 0 mm; - 0.12 mm
• Thickness: ± 0.15 mm
• Surface figure: Plano: L/20 (10.6 µm) up to Ø 75 mm
  Concave: L/20 (10.6 µm) up to Ø 50 mm
• Surface roughness: = 5 Å rms
• Wedge: < 3 arc min
• Clear aperture: 90?% of diameter
• Laser damage threshold:
  Gold mirror: typ. 40 kW (cw) for Ø 10 mm (4000 W/mm)
  MaxR-mirror: typ. 20 kW (cw) für Ø 10 mm (2000 W/mm)

• Polished nickel-plated copper coated with hard gold
• Reflectivity: R > 98.8?% for 2 – 20 µm
• Angle independent
• Lowest possible phase shift: < 1°

• Polished nickel-plated copper with dielectric coating
• Reflectivity: R > 99.8 % for 9 – 11 µm, 45°
• Phase shift: < 2°

Silicon mirrors are lighter than copper mirrors and lend themselves to lightweight applications with small to medium power output. Silicon mirrors are generally coated with silver and/or dielectric coatings.

The following are available

• Diameter from 5 mm to 150 mm
• Radii from 1 to 60 m (concave, convex)
• Round/rectangular shapes

Specifications

• Diameter: + 0 mm; - 0.125 mm
• Thickness: ± 0.1 mm
• Surface figure: L at 633 nm
• Wedge: < 3 arc min
• Laser damage threshold: typ. 4 kW for Ø 10 mm

Molybdenum mirrors are uncoated and used in applications in which coated mirrors would normally become damaged by the high output power or harsh environmental conditions.

The following are available:

• Diameter from 15 mm to 100 mm
• Radii from 1 m to 30 m (concave, convex)
• Round/rectangular shapes

Specifications:

• Reflectivity: R = 98.5?% (10.6 µm)
• Diameter: + 0 mm; - 0.1 mm
• Thickness: ± 0.1mm
• Wedge: < 3 arc min
• Surface figure: L/20 (10.6 µm) over Ø 50 mm
• Surface quality: 60-40 per MIL-O-1380A
• Clear Aperture: 90 % of diameter
• Laser damage threshold: typ. 60 kW for Ø 10 mm (6000 W/mm)