What's the average and maximum Reflectance variation from lot to lot? As described on the previous tab, LIDT values in the nanosecond pulse regime scale with the square root of the laser pulse duration: This adjustment factor results in LIDT values of 0.45 J/cm2 for the BB1-E01 broadband mirror and 1.6 J/cm2 for the Nd:YAG laser line mirror, which are to be compared with the 0.7 J/cm2 maximum energy density of the beam. Stash it away! Now compare the maximum power density to that which is specified as the LIDT for the optic. 4**: Protected aluminum spectral reflectivity Enhanced aluminum is similar to protected aluminum except that it consists of multiple layers of dielectric coatings to improve mirror reflectivity at certain spectral regions. It provides an average reflection of approximately 97% in the visible wavelength range. S1: Flatness 1-3 waves per Dia 25.4mm(Up to lambda/4 by request), Material: Optical grade glass, Fused Silica or Silicon, S1: Flatness 1-3 waves per Dia25.4mm (Up to lambda/4), Material: Optical grade glass, Fused Silica, Silicon. Protected Aluminum is the most commonly used metal coating for less demanding, … Jeff. Regards, Response from Chris at Thorlabs: Thank you for your feedback. I need by one mirror for laser reflection to make grating. Durability:  Meets specifications of MIL-M-13508 and various other military specifications. Etay, 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. Do you by chance have data on the tolerable ambient temperature range of these mirrors? 91, 127402 (2003). You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. If the optic was tested at a wavelength other than your operating wavelength, the damage threshold must be scaled appropriately [3]. Response from Bweh at Thorlabs USA: Sorry we don't have this data at this time. Hello, Zaki Ahmad, in Principles of Corrosion Engineering and Corrosion Control, 2006. 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. EMF offers a broad range of aluminum metallic mirror coatings for first surface mirrors and second surface mirrors across a wide wavelength range. In this case, the absorptive filter is the best choice in order to avoid optical damage. Reflective Coating: Protected Aluminum • Typically coated with either disilicon trioxide or magnesium fluoride depending on incident light spectrum • Improved corruption resistance and rugged enough to withstand ordinary handling and cleaning • Some sensitivity to light polarization and angle of incidence • Lowerd average reflectance Features. Xavier. For applications which require extremely low thermal expansion, Thorlabs also offers UV-enhanced and protected aluminum Zerodur mirrors. We do have unpolarized data for our UV-Enhanced Aluminum mirrors down to 200 nm. From these curves, I really do not see how you can have the nerve to call that mirror a "UV enhanced Aluminum mirror"!!!!!! Lett. The average energy density of each pulse is found by dividing the pulse energy by the beam area: As described above, the maximum energy density of a Gaussian beam is about twice the average energy density. 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 formation of an Al 2 O 3 layer affords protection to the base metals. 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. Aluminum coatings are more resistant to corrosion in the atmosphere than zinc coatings. Aluminum coated mirrors are an excellent option for many general broadband applications. If your power density is less than the adjusted LIDT of the optic, then the optic should work for your application. Hello, thank you for your feedback. Please add products before saving :). Thanks! However your responses to earlier inquiries indicates that you have some data for shorter wavelengths. Protected Aluminum coated mirrors are a good option for many general broadband applications. While the test results are only representative of one coating run, Thorlabs specifies damage threshold values that account for coating variances. So, in many cases, an aluminum metallic mirror coating is preferred over a protected silver coating. For a Gaussian output, these specifications result in a maximum energy density of 0.1 J/cm2. A Tech Support representative will contact you directly with more information. Keep in mind that this calculation is only used for pulses between 10-9 s and 10-7 s. For pulses between 10-7 s and 10-4 s, the CW LIDT must also be checked before deeming the optic appropriate for your application.