Tuesday, November 18, 2014

Techy Tuesday - Printed Optics

Optics run the gamut from cheap plastic toys you get for kids to play with (and destroy), through eyeglass lenses and on to the most precise surfaces mankind knows how to make.  There's a world of difference in quality between small magnifiers and imaging optics from a camera or telescope.  In light of that range, you need to narrow down the range when someone tells you 3D printed optics are really here. 

Most eyeglasses and a large percentage of the low to mid-end optics on the market are injection molded.  Injection molding is process that forces heated plastic under pressure into a lens mold that forms the shape.  Molds are custom made and expensive, though, so it's really hard to tweak a mold if you need to improve your design.  This is a niche where quick-turnaround prototypes of printed optics might well grab some market. 

The Dutch manufacturing company LUXeXcel has announced a proprietary solution for 3D printing optics intended to compete with injection molding. They claim:
  • No investments in tooling or molds
  • Uncomparable manufacturing and delivery speed
  • Digital process, online ordering on demand
  • No inventory needed, so no obsolete's
  • Complete shape freedom
  • Customization for any specific optical solution
If you've seen anything that came off a 3D printer, you've probably noticed it's usually very easy to see the layers the printer laid down; that would destroy any image and probably any optical use.  So how does LUXeXcel get around that?  By printing a clear, UV-cured plastic.  Transparent droplets of the polymer are jetted and cured by powerful ultraviolet (UV) lamps integrated into the print head, according to a description on the company's blog. The 1,440 dpi print head is controlled by piezoelectricity.  Delaying the time elapsed between when the polymer droplets are jetted and when the UV light is applied gives the droplets enough time to lose their shape and flow together, resulting in a smooth surface.
You can see the smoothness in this sample of a total internal reflection lens.  It almost looks like polished glass in this picture. 

LUXeXceL has used their "Printopical" technology for making Fresnel lenses, window treatments and foils, digital art, and advertising graphics and even some eyeglasses. Its main focus has been making rapid prototypes, small batches, and some higher volumes of LED optical components, structures, and diffusers, mostly for the lighting industry.  All of these things are typically made by injection molding. 

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