Reflective apertures, stops and shutters

Sometimes a high power infra red laser needs to have its power attenuated, or have strongly diverging modes removed from the beam. At Laser Beam Products we manufacture mirrors with precision through holes or with sharp knife edges that are very cost effective, even when made to your design as a one-off prototype.

We usually advise customers that the length of the hole is no more than the hole diameter, to avoid having a “tunnel” with an aperture at either end. We can make tapered holes to avoid this problem. Because our Gold coating is applied electrochemically the internal bore of any hole is also Gold coated.GoldPrismHoleFlippedIf an acousto-optic modulator (AOM) is being used, a reflective aperture can be used to manipulate one of the beam orders to be reflected and the other to be transmitted. We can make through holes as small as 1 mm diameter very accurately.

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Automotive customer saves $15,000

Some of our aerospace and automotive customers insist we offer a RTV (Return To Vendor) repair programme to reduce the overall cost of ownership of laser equipment. It saves time, money and valuable materials, and is well worth doing.  The reworked mirrors are as good as new so there is no loss of quality or productivity. It can also contribute to ISO 14001 Environmental Management Here’s a great case study…

One of our customers, a European automotive manufacturer, sent us a collection of used mirrors from their production line that had accumulated minor burns and scratches, and had been swapped out.  They were large, complex water cooled beam delivery mirrors which we repolished and recoated to a condition that was as good as new. The mirrors were repaired and returned in under 3 weeks.

The customer was delighted and told us the mirrors were working perfectly, and had saved them $15,000 on the cost of new mirrors!. They have since had them reworked three more times.

Here’s an example of another customer’s mirrors that we reworked to a ‘good as new’ condition. These were from a gas sensing cell made by a company who stopped supporting their equipment. You can find out more on our website.

Reworked Mirror

Laser Beam Products at Photonics West 2015

?????? It’s that time of year again and we’re preparing for our next trip to San Francisco for the Photonics West exhibition from 10-12 February 2015. If you’re planning to visit, pop by and see us at the British Pavilion, Booth 5117.

As well as exhibiting our core range of metal mirrors, we will also be looking to talk to customers who want to make their own coatings on our low scatter metal substrates. Although we offer our mirrors with a range of coatings for use with soft UV, visible, IR and even THz wavelengths, there are times when our customers want to make their own coatings.

We will provide the mirror substrates super polished, cleaned and ready for further coating. Most of our mirrors use an amorphous layer of electroless nickel much favoured by coaters, as there are no issues with oxidation, staining or complex vacuum packing restrictions. It’s not just optical coating either, we have customers specifying functional coatings chosen for their hardness, magnetic or electrical properties.

 

Gold coating for metal mirrors

Did you know that our chemically deposited Gold coating has a reflectivity that is almost invariant with small changes in angle of incidence? This means for scanning applications, where the mirror operates at a varying angle of incidence, the reflected power is quite consistent across all scan angles. Dielectric mirror coatings can change reflectivity with incident angle dramatically, and have to be specified carefully

The Gold coating also has consistent reflectivity from face to face for multi faceted mirrors, reducing variations in power during scanning.

No tooling or batch charges are made for our Gold coating, even when coating a single mirror. We offer Gold coating on mirrors made from Copper, Aluminium, Nickel, Brass, Beryllium/Copper, Stainless Steel and other metals and alloys.

See our web page laser gold mirror

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Pyramidal mirror

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Lightweight Aluminium Mirror 

 

Polished laser mirrors – simply better surfaces

Following on from a blog article we published in December 2012, we now have more data about why our chemically polished mirrors perform better than those made by diamond machining.

diamond_machined_newsWe had a number of visitors to our stand at the Laser World of Photonics Show in Munich last year talking about this very subject.  This photo shows you clearly the surface roughness of a diamond machined mirror that results in scatter and diffraction.

The surface roughness of such a mirror may well be measured as quite good, in this case we were told Ra = 5nm. A single descriptor for surface roughness (e.g., Ra, Rq, Rz,) can be misleading in evaluating surface roughness though. Two surfaces, one polished and one diamond turned, can yield near identical roughness values, yet behave entirely differently.

The repetitive nature of diamond tool marks can make a diamond turned surface with a specified surface roughness value unacceptable for visible, and certainly UV &  X-ray wavelengths. A polished surface (with ‘random’ surface imperfections, but an identical roughness value) would be perfectly adequate. Hence many diamond turned or SPDT optics for visible and UV applications are often post-polished.

If coated, these SPDT artefacts will cause rapid changes in coating thickness. With high power lasers, the sharp edges or “cusps” on the diamond turned surface will add a shear stress to the coating and the coating may fail. Our proprietary polishing technique is very effective in removing the mid spatial frequency surface roughness and this is a significant improvement for visible optics.

If you want more information our newsletter of June 2014 has the surface roughness values and can be found on our website. You can also visit our web page that tells you more about our custom lapping and polishing services for laser and non-laser applications.