Optics components such as filters, windows and lenses are often cemented into protective metal rings, usually made of aluminum. Rings can be one or two part (one close-fitting inside the other). They can be black anodized for non-reflectivity.
Select from the drawings below. Special variations are easily machined. We stock some sizes in small quantities. Rings can also be manufactured in custom sizes with threaded outside and inside configurations (for use with retaining rings).