We’ve recently published an article in our newsletter about an increase in demand for our mirror reworking service. This isn’t just idle boasting, it is a result of OEMs dramatically cutting support for installed CO2 lasers, including a big reduction in stocks of spare parts.
This is probably because the bulk of current OEM production is now focused on fiber lasers, therefore support for existing CO2 laser users has been cut. So at LBP we’ve seen a corresponding increase in demand for laser mirror repairs, not just for truly obscure mirrors but for parts that were standard and widely available just 2 or 3 years ago.
We regularly repair, polish and coat a wide range of mirrors, including copper and molybdenum, to a ‘good as new’ condition, saving our customers time and money.
We have recently developed the gold coating of carefully roughened metal substrates to be used as diffuse reflectors. This particular example, based on Aluminium, has a consistent surface roughness of Ra=6um and would be useful in the near infra red.
The surface roughness needs to be random enough to allow the surface to function as an isotropic diffuse reflector for infra red wavelengths. Additionally the magnitude of the surface roughness needs to be high enough so the reflectance will be perfectly diffuse and have no enhanced reflectance in the specular direction. We are happy to coat customer supplied material and we can provide measurements of the surface texture.
We regularly make and repair mirrors for CO2 lasers that the Original Equipment Manufacturer has stopped supporting. This can be shortly after purchase if the OEM has ceased trading, or sometimes a cynical ploy by the OEM to force their customers into replacing perfectly serviceable systems before the end of their working life. There is a guide to reworking laser mirrors on our web site
Gas cell repair
It seems laboratory equipment is similarly affected and, we have had a rush in repairing mirrors for multi-pass gas cells used in environmental monitoring or for chemical analysis. We’ve seen that the original mirrors tend to be of very poor quality to begin with. One customer fitting a re-polished and freshly Gold coated mirror was amazed by the huge increase in signal output, so much so that it swamped the detector. For him it turned out to be more of an upgrade than a repair. Here is a nice animation that show the beam path in a “White Cell”
If you have any mirrors that need replacing or repairing and you’re not getting any support from the OEM. talk to us. If you send us as much information as you can about the part including original packaging, specifications and photos, or send us the original parts to inspect and we will let you know if we can help.
Trouble awaits anyone not realising that the term “CO₂ laser optics” is mostly understood to refer to optics designed for the common CW (Continuous Wave) CO2 laser types (fast axial flow, slab discharge etc). A customer with a high power TEA pulsed laser using mirrors they sourced form Germany found they completely failed within a few seconds due to the very high laser pulse energies. After waiting several months for the mirrors to be delivered, a few seconds of use was disappointing!
We have recently helped several customers using TEA (Transversely Excited Atmospheric) CO₂ lasers, which are a PULSED CO₂ laser type.
Pulsed Laser Damage
Our Gold coating works with both high power CW and Megawatt pulsed TEA lasers. For this customer we were able to take the used failed mirrors, remove the remains of the ablated dielectric coating, Gold coat them, and return them, taking just a few days.
Interestingly the first true high power TEA CO₂ laser was developed in Baldock, England, just 5 miles away from our factory here in Biggleswade.
Our Gold coated Copper mirrors have been independently certificated as having an LIDT of 46J/cm² in a 80ns pulse. Our competitors products with dielectric coatings were measured at less than 10J/cm2 so quite an advantage
Over the last year or two we’ve had an increasing number of requests from customers for mirrors that have extremely parallel front and back surfaces. This ‘extreme parallelism’ means that when customers are replacing a used mirror in laser system with a new one, there’s can be almost no adjustment needed.
Aligning optical systems is a tricky and time-consuming job, not to mention the exposure to the hazards of high power laser systems. So by using our electronic autocollimator, we can measure parallelism to an accuracy of 1 arc second, and make this job quicker and easier for customers. Our autocollimator gives a hard copy report of the results, including statistical analysis.
Another way in which we can make the assembly of new systems faster and simpler is by offering high angular accuracy and mirror to mirror repeatability on ‘lipstick’ type mirrors. This means that assembly needs less skilled staff or specialised production equipment.
An angular error of 1 arc minute on the mirror is doubled by the reflected beam, and results in a positional error of 5 mm for every 10 Metres of beam travel