In Europe, apart from Thorlabs, Newport or Radiant Dyes, would you recommend other providers of optical and optomechanical elements (lens mounts, breadboards, translation stages, piezo systems, ...) ?
I find Edmund optics are cheaper for the optics (mirrors, lenses, in particular filters and dichroics), with thor labs for better quality optomechanics.
We buy customed lenses and prisms from BFI Optilas and Korth Kristalle for applications that require specific dimensions, materials or focal lengths. Regarding interferometric optical filters, I only trust in AHF analysentechnik AG, especially when customed-dimension ultraflat components are required.
Guillaume, More than others' answers, I recommend you CVI laser optics (CVIlaseroptics.com) as a provider of high performance optical components in laser systems particularly in UV. Regards, Shigeo
In addition to the above I can also recommend LIOPtec for optomechanics. They make excellent kinematic mirror mounts with screws with a high TPI. They are on a par with the Thorlabs "Polaris" mounts, but much cheaper. Also, they come anodized in a range of colours - it might sounds frivolous, but it really helps on a busy optical table!
For optical elements I recommend Artifex Engineering (https://artifex-engineering.com/). They offer custom optics and do offer a nice trade off between price and fast delivery.