I will send you the newest data for our silver coating directly. Reflectance is denoted by ρ (or p). Community Forum Software by IP.BoardLicensed to: Cloudy Nights, This is not recommended for shared computers, binoculars vs a telescope of higher aperture and faster speed, Harmonic Reed Starmaster "Giant" Telescope, starting to love this automation stuff - sleeping on a horsehead. 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. Dear Sir or Madam,
I have seen comments before that coaters sometimes find that simply cleaning mirrors sent to them has a substantial impact (with numbers quoted), even though they will be recoated anyway. Hello Jale, thank you for contacting Thorlabs. While the LIDT, when expressed in units of J/cm², scales independently of spot size; large beam sizes are more likely to illuminate a larger number of defects which can lead to greater variances in the LIDT . For beams with a high PRF both the average and peak powers must be compared to the equivalent CW power. I am wary of having a camera that is reliable and reproducible over at least a decade probably more like two decades. Thank you for contacting Thorlabs. looking for VNIR mirror I did not see
to integrate on a shutter blade, I need a custom sized protected silver mirror (ideally P-02) with a size of 17 x 24x 1.1 mm.
Note the Thorlabs beam profiler can have a exposure as short as 20us far shorter than most DSLR's. Because dust or other particles on the surface of an optic can cause damage at lower thresholds, we recommend keeping surfaces clean and free of debris. The shaded regions in the graphs denote the ranges over which we guarantee the specified reflectance. Response from Javier at Thorlabs to mbrodeur: Thank you for submitting your request. The graph to the right shows why expressing the LIDT as an energy density provides the best metric for short pulse sources. See also: cavities, Fabry–Pérot interferometers, supermirrors, reference cavities, bandwidth, Q factor, free spectral rangeand other articles in the category optical resonators. If there is some off the shelf meter I can use for this, that would be ideal. A naive calculation of the average linear power density of this beam would yield a value of 0.5 W/cm, given by the total power divided by the beam diameter: However, the maximum power density of a Gaussian beam is about twice the maximum power density of a uniform beam, as shown in the graph to the right. This calculator assumes a Gaussian beam profile, so a correction factor must be introduced for other beam shapes (uniform, etc.). You must now adjust this energy density to account for hotspots or other nonuniform intensity profiles and roughly calculate a maximum energy density. Hello there. Various basic properties characterize a mirror: Figure 1: Reflection of light on a mirror. Is this damage caused by average or by peak power? I am using the PFSQ10-03-P01 mirror. If the laser beam diameter is increased by 10x a filter with an attenuation of around 1 million or so should suffice. Measuring its reflectance directly by using reflectance spectrophotometry showed that Mirror 2 has much worse performance and a trailing reflectance that drops to 0.5% less than that of Mirror 1 due to absorption and scattering (Figure 3). your website, social media, a discussion forum, Wikipedia), you can get the required code here. You know that the image is real if it is described as being upright. for both p and s polarization? The microscan probe appears to resemble a miniature integrating sphere. The following NIST paper illustrates the geometry and setup for measuring specular reflectance with an integrating sphere; Although this is for the infrared the setup is the same (apart from the detector) for the visible. An applications engineer from our team in China will reach out to you directly. Let's say we have a 1070nm, 1kW-10ms-10Hz pulsed laser with 10mm diameter. 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. Tax Certificates, High reflectivity laser mirrors are critical components for beam steering, The industry standard method of measuring reflectivity does not tell the whole story, Reflectivity may seem simple but is actually a difficult value to measure, Cavity ring down spectroscopy (CRDS) measures total loss in order to determine reflectivity. where the approximation holds for low round-trip losses (e.g., <10%), i.e., only for high finesse values. The reflected laser light oscillates in the resonant cavity and a small amount of light is lost with each reflection. Reflection and the Ray Model of Light - Lesson 3 - Concave Mirrors. TECHSPEC® Laser Line Mirrors offer >99.98% reflectivity at 1064nm and high damage thresholds of up to 6 J/cm2 @ 355nm. Response from Tim at Thorlabs: Thank you for contacting us. 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. For reference a Gaussian beam typically has a maximum energy density that is twice that of the 1/e2 beam. One could probably construct something equivalent to the micro scan. × LightMachinery Etalon Model Review. Next, the power/energy is either increased or decreased and the optic is exposed at 10 new locations. 2) Measure the power of the beam specularly reflected by the mirror. Determine the image distance and image height for a 5.00-cm tall object placed 10.0 cm from a concave mirror having a focal length of 15.0 cm. The results of this calculation … Kind regards,
You must now consider hotspots in the beam or other non-uniform intensity profiles and roughly calculate a maximum power density. Maria. For our full selection of optics for ultrafast applications, please see the Ultrafast Optics tab. Response from Javier at Thorlabs to cdurfee: Thank you for your feedback. Since this contribution is proportional to the square and higher powers of the reflection coefficient, it can often be neglected. As described on the previous tab, the LIDT value of an optic scales with the square root of the wavelength in the nanosecond pulse regime: This scaling gives adjusted LIDT values of 0.08 J/cm2 for the reflective filter and 14 J/cm2 for the absorptive filter. But this would likely require to integrate the signal strength over the pixels illuminated, assuredly if the spots direct and after reflection differ in size. While many optics can handle high power CW lasers, cemented (e.g., achromatic doublets) or highly absorptive (e.g., ND filters) optics tend to have lower CW damage thresholds. However, this false assumption does not consider scatter or absorption, leading to overly optimistic reflectivity values. The total loss of the mirrors is determined by the decay time, or “ring down”, of the reflected light. I have contacted you with phase shift data. Hello, which mount can I use with the mirror PF30-03-P01 ? While the above procedure provides a good rule of thumb for LIDT values, please contact Tech Support if your wavelength is different from the specified LIDT wavelength. Ask RP Photonics for advice on optical cavities, including dispersion effects, the use for laser stabilization, etc. Reflectance can be categorized into two types. TECHSPEC® Laser Line λ/20 High Tolerance Right Angle Mirrors feature >99.5% reflectivity at Nd:YAG wavelengths. Ray diagrams provide useful information about object-image relationships, yet fail to provide the information in a quantitative form. Response from Buki at Thorlabs:
Continuous wave (CW) lasers typically cause damage from thermal effects (absorption either in the coating or in the substrate). Could you send me the data of phase shift for protected silver coated mirror? (Please enter the sum of thirteen and three in the form of digits!). The optical cavity thus obtained is called a Fabry-Perot cavity and is shown below. For long pulses to CW, linear power density becomes a constant with spot size. Unfortunately, it can be very difficult to compare the LIDT specification of an optic to your laser. I would guess many visitors would have the requirements. I have reached out to you directly to troubleshoot this. You have the raw data for the gold mirror reflectivity at 0 deg and 45 degrees, but you dont have the data for silver or aluminium listed. Maria, Dear Sir or Madam,
When choosing optics, it is important to understand the Laser Induced Damage Threshold (LIDT) of the optics being used. Is there any specification regarding the surface roughness of your mirrors? The idea here is to isolate to only the light being tested, AND to present a consistent angular diameter for all incoming light and thereby eliminate the variable of differing extraneous, outer field illumination that could result in differing veiling glare superimposed upon the test aperture. For data presented here, a <1 mm beam size was used to measure the LIDT.