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High-reflection (HR) Dielectric Mirror Coatings
HR mirror coatings consist of layers of dielectric materials (i.e. not metals, which are used in mirrors for consumer goods) and are designed to achieve the highest possible reflectance, usually at specific wavelengths. Although engineered for best performance at normal (0) or 45 degrees angles-of-incidence, these coatings can be tailored for most any angle. 1. Laser line HR coating This type of multilayer dielectric coating is often employed in laser applications where low scattering is important. Typical reflectivity value for S-polarization is greater than 99.5% and P-polarization greater than 99%. Wavelength, nm | Reflection, % | AOI, deg | Polarization | Damage threshold,
J/cm2, 10 ns pulse
| 248 | >=99.5 | 0, 45 | S | 2 | >=99.0 | 45 | P, UNP(unpolarized) | 266 | >=99.5 | 0, 45 | S | 2 | >=99.0 | 45 | P, UNP | 308 | >=99.5 | 0, 45 | S | 2 | >=99.0 | 45 | P, UNP | 337 | >=99.5 | 0, 45 | S | 2.5 | >=99.0 | 45 | P, UNP | 355 | >=99.5 | 0, 45 | S | 2.5 | >=99.0 | 45 | P, UNP | 532 | >=99.5 | 0, 45 | S | 3.5 | >=99.0 | 45 | P, UNP | 633 | >=99.5 | 0, 45 | S | 4 | >=99.0 | 45 | P, UNP | 1064 | >=99.5 | 0, 45 | S | 5 | >=99.0 | 45 | P, UNP | 1550 | >=99.5 | 0, 45 | S | 3 | >=99.0 | 45 | P, UNP | 2100 | >=99.0 | 0, 45 | S | 2.5 | >=98.5 | 45 | P, UNP | 10600 | >99.0 | 0 | S, P, UNP | >1 kW/cm2, CW mode |
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Fig. 1-1 HR coating at 248 nm for S- and P-polarization, AOI=45°.
Fig. 1-2 HR coating at 1064 nm for S- and P-polarization, AOI=45°.
2. Dual-wavelength HR coating TYDEX has achieved considerable success in making dual-wavelength high-reflectors. Because YAG laser technology is very advanced in Russia, we are able to deliver very impressive YAG (and related) optics. TYDEX' dual-band mirrors for 1064 nm and 532 nm have proven to be just as good as those produced at the top US and European companies, at considerably lower cost. This impressive performance is achieved using highly resourceful Tydex' coating engineers who have pushed e-beam technology to its limits. Wavelength, nm | R, % | AOI, deg | Polarization | Damage threshold,
J/cm2, 10 ns pulse
| 355 and 532 | >=99.0 and >=99.5 respectively | 0 | any | 3 | 532 and 1064 | >=99.5 at each wavelength | 0 | any | 4 |
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Fig. 2-1 Reflection vs. wavelength for HR coating R>99% at 335 nm and R>99.5 at 532 nm, AOI=0°.
Fig. 2-2 Reflection vs. wavelength for HR (R>99.5%) coating at 532 nm and 1064 nm, AOI=0°.
3. Broadband HR coating Although broadband HR coatings can be metallic or dielectric, the dielectric versions are specified here. See section VI for metallic coatings. Wavelength range, nm | Reflection per surface, % | AOI, deg | Damage threshold,
J/cm2, 10 ns pulse
| 260-340 | >=99.0 | 0 | 2 | 350-450 | >=99.0 | 0 | 2 | 700-900 | >=99.0 | 0 | 4 | 900-1100 | >=99.0 | 0 | 4 |
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Fig. 3-1 HR coating at 260-340 nm, AOI=0°.
Fig. 3-2 HR coating at 720-900 nm, AOI=0°.
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