Ultra-thin Windows with High Flatness

Femto-line lasers and associated applications have been evolving fast in recent years, some demanding components are needed to make Femto-line laser systems, one of them is the small thickness (such as 0.1mm, 0.2mm) windows or substrates with high flatness (Lambda/10 or Lambda/4 @633nm).

Classical single-surface polishing methods are often used to make high precision laser grade optics products, but it is difficult to make high-flatness optics with small thicknesses using the classical method. In the classical polishing procedure, the polished optics are often put on a pitch plate to be polished, even though you get a high-quality surface (which means high surface quality and high flatness) in polishing, when it is taken off the pitch plate, the flatness would be lowered. This is because there is stress in the optics when it is bonded to the pitch plate, when it is taken off the pitch plate, the stress is released, and the flatness would be lowered with the stress released, as the thicknesses of the optics are very small, proportionately, the flatness would become much lower. This is why manufacturing high flatness and ultra-thin windows using the classical polishing method is always challenging for manufacturers.

Hangzhou Shalom EO has developed a double surface polishing method to make high-precision optical windows or substrates, where two surfaces of the optic are polished simultaneously in one go, and the optics don’t need to be put on a pitch plate in the polishing procedure, so there is no stress releasing problem, resulting in no flatness change when it is taken from the tools. The double surface polishing method has not been incorporated in precise optics fabrication before because the finished optics produced by this method have the defect of low surface quality (that is, larger S/D). Hangzhou Shalom EO has overcome this obstacle by achieving a groundbreaking improvement in the polishing technique and completing a radical overhaul on our polishing machine, raising the surface quality to 10/5 S/D, while exploiting the benefits of the double surface polishing method of precise surface flatness. Furthermore, excellent parallelism(10 arcsec) is also realized on the UVFS Ultra-thin Windows or Substrates.

Using our improved double surface polishing machine, we can make the laser grade small thickness windows and substrate like the following (materials: BK7 or fused silica):

Ultra Thin Windows with High Flatness:

Product Features:

• Off-the-shelf and custom modules are available
• Made of BK7, UVFS, or Quartz Crystals
• Minute thickness and high surface flatness
• Surface quality 10/5 and parallelism 10”
• Minimum thickness: 0.03mm, minimum size: 0.5mm
• Uncoated mirror substrates and custom AR coating options are available

Product Modules:

If you are looking for  standard size products click here