Remember, anyone who has the unique link to your cart will be able to retrieve it. [2] Roger M. Wood, Laser-Induced Damage of Optical Materials (Institute of Physics Publishing, Philadelphia, PA, 2003). Our UV-Enhanced Aluminum mirrors are a cost effective solution for UV applications. According to the test, the damage threshold of the mirror was 2.00 J/cm2 (532 nm, 10 ns pulse, 10 Hz, Ø0.803 mm). The spreadsheet will then calculate a linear power density for CW and pulsed systems, as well as an energy density value for pulsed systems. The pulse length must now be compensated for. Pulsed lasers, on the other hand, often strip electrons from the lattice structure of an optic before causing thermal damage. Economy Front Surface Mirrors with Protected Metallic Coatings, Ultrafast-Enhanced Silver Mirrors, 750 - 1000 nm, Round and Square Versions Available From Stock, Packages of 10 Rounds at a Discounted Price, Surface Flatness: λ/10 (λ/8 for 2" x 2" Squares), 10 Packs of Round Mirrors Available at a Discount, This variation of our protected silver coating is only found on the. LIDT in linear power density vs. pulse length and spot size. This means that both CW and pulsed damage thresholds must be compared to the laser beam to determine whether the optic is suitable for your application. Unfortunately, this is highly dependent on factors such as absorption and thermal diffusivity, so there is no reliable method for determining when a high PRF laser will damage an optic due to thermal effects. You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. If your maximum energy density is less than this adjusted LIDT maximum energy density, then the optic should be suitable for your application. In order to use the specified CW damage threshold of an optic, it is necessary to know the following: Thorlabs expresses LIDT for CW lasers as a linear power density measured in W/cm. For long pulses to CW, linear power density becomes a constant with spot size. The calculation above assumes a uniform beam intensity profile. Please add products before saving :). Absorption is either due to an intrinsic property of the optic or due to surface irregularities; thus LIDT values are only valid for optics meeting or exceeding the surface quality specifications given by a manufacturer. CW damage threshold values typically scale directly with the wavelength of the laser source, so this yields an adjusted LIDT value: The adjusted LIDT value of 350 W/cm x (1319 nm / 1550 nm) = 298 W/cm is significantly higher than the calculated maximum linear power density of the laser system, so it would be safe to use this doublet lens for this application. Such common coatings for these applications include Enhanced Aluminum and Protected Gold Coatings. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately. A protected or enhanced aluminum coating has less chance of tarnishing than protected silver in a high humidity environment while providing good reflectance. EMF optical design engineers can help you design a custom metallic mirror coating to meet your exact specifications and performance requirements. In this ultra-short-pulse regime various mechanics, such as multiphoton-avalanche ionization, take over as the predominate damage mechanism [2]. They are as durable and reliable as protected aluminum mirrors. For applications which require extremely low thermal expansion, Thorlabs also offers UV-enhanced and protected aluminum Zerodur mirrors. Approximate intensity profile of your beam (e.g., Gaussian), Linear power density of your beam (total power divided by 1/e, Energy density of your beam (total energy divided by 1/e, Pulse repetition frequency (prf) of your laser, The power density of your beam should be calculated in terms of W/cm. 29, 517 (1998). This can be compared to the LIDT values for a WPQ10E-980 polymer zero-order quarter-wave plate, which are 5 W/cm for CW radiation at 810 nm and 5 J/cm2 for a 10 ns pulse at 810 nm. The number of locations that are damaged at a particular power/energy level is recorded. Page 1 of 2 - Enhanced Mirror Coatings? A histogram such as that below represents the testing of one BB1-E02 mirror. Peak reflectance in the visible is > 93%, while average reflectivity is > 95%. Contact Tech Support for more information. This graph was obtained from [1]. These aluminum mirrors are enhanced with a high quality multilayer dielectric coating to both protect the aluminum coating and increase reflectivity at mid-visible wavelengths. Custom designed solutions are also available. For pulse widths between 1 - 100 ns, an approximation is as follows: Use this formula to calculate the Adjusted LIDT for an optic based on your pulse length. On the other hand, the pulsed LIDT scales with the square root of the laser wavelength and the square root of the pulse duration, resulting in an adjusted value of 55 J/cm2 for a 1 µs pulse at 980 nm. [1] R. M. Wood, Optics and Laser Tech. Pulses shorter than 10-9 s cannot be compared to our specified LIDT values with much reliability. However, the large average linear power density of the laser system may cause thermal damage to the optic, much like a high-power CW beam. The following is a general overview of how laser induced damage thresholds are measured and how the values may be utilized in determining the appropriateness of an optic for a given application. There are multiple regimes in which a pulsed laser can damage an optic and this is based on the laser's pulse length. As a result, both CW and pulsed LIDT values must be compared to the properties of the laser system to ensure safe operation. This diameter provides a larger clear aperture than Ø1/2" optics while allowing the mounts to maintain a Ø1" footprint. Ø7 mm mirrors are compatible with our MK7 (MK7/M) Mini-Series kinematic mirror mount or our LMR7 (LMR7/M) fixed optic mount. This addition to the coating provides an abrasion-resistant surface while maintaining the performance of aluminum mirror. To receive more information or inquire about a custom order, please contact Tech Support. Are you? This process is repeated until damage is observed. Opt. As before, the CW LIDT of the optic scales linearly with the laser wavelength, resulting in an adjusted CW value of 6 W/cm at 980 nm. Remember that absorption by optics or coatings can significantly reduce LIDT in some spectral regions. A good rule of thumb is that the damage threshold has an inverse square root relationship with wavelength such that as you move to shorter wavelengths, the damage threshold decreases (i.e., a LIDT of 1 J/cm2 at 1064 nm scales to 0.7 J/cm2 at 532 nm): You now have a wavelength-adjusted energy density, which you will use in the following step. The shaded regions in the graphs denote the ranges over which we guarantee the specified reflectance. We're ready! So far I have found:Protected Aluminum/Silicon Monoxide 89% reflectanceSimi-Enhanced Aluminum…