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Metallizing plastic diffraction gratings


Q. I am working on plastic diffraction gratings.These gratings will consist of injection molded parts with grooves 5 microns deep. The material will be ABS or polycarbonate. I need to apply a reflective metallic coating to the part. The electroplating process needs to be very controlled because of the tiny groove depth.

Fernando Erismann
C&K Systems

A. Hi, Fernando. For low volumes, the easiest and most practical idea is "two-part silvering" where you simultaneously spray silver nitrate and a reducing agent onto the grating. The small grooves should be no problem at all. However, you may want to apply it on a spin table to insure full coverage and no air bubbles preventing wetting.


Ted Mooney, Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey


A. It never ceases to amaze me how this kind of plating is possible at all. The results are nothing short of specular(!). And yet, it is only one of the many challenging, exciting, and rewarding fields in platingdom.

You have to see an operation of this kind to believe it. Plating is the way to make a mold of a surface like this for mass reproduction.

tom pullizi signature
Tom Pullizzi
Falls Township, Pennsylvania


A. Fernando:
Sounds like the processing used to manufacture compact disks is something you should look in to.

CDs are molded from low molecular weight polycarbonate with pits on the order of 0.5um wide and 0.1um deep. These are produced from a photosensitive glass "master" disk from which a galvanic nickel negative "father" is made. A positive "father" is made from additional galvanic nickel deposits. From these "fathers", a "mother" and subsequent "sons" are made in a similar way.

ASM vol5
ASM Metals Handbook vol. 5

Surface Engineering

Electroplating Engineering Handbook
by Larry Durney
from Abe Books


The "sons" are used in an injection molding process to produce the disks. The moldings are then metallized (vacuum vapor deposition) and coated with varnish to complete the disk.

You may be able to take advantage of some of these techniques.

Brian Cardwell
Ford Motor Company


Q. Dear Sir,

can I use CD as a diffraction grating for the separating of the ultraviolet ? It is necessary for my greenhouse optimisation.

Best Regards

Rifat Tarik Yararbas
- Izmir TURKEY

sidebar (2004)


This is a little off-topic. My son has a science project where he has to grow a plant with light that passes through a plastic diffraction grating to break it into different colors. I have contacted numerous camera stores (as his teacher suggested), educational toy stores, and hobby shops with no luck. Any suggestions?

Thank you for your consideration,

PS I never even heard of diffraction grating plastic until now and I arrived here via a Google search.

Bruce Hirshfield
- Charlotte, North Carolina


Looking for source of diffraction gratings for art project.

William Martin
- Thomaston, Maine

Edmund Scientifics and Sargent-Welch have diffraction grating sheets. Good luck.

Ted Mooney,
Teds signature
Ted Mooney, P.E.
Pine Beach, New Jersey

September 5, 2008

I do artwork about Heaven and would be interested in finding out if I can add refraction gratings to my pictures on plastic sheets? As it is we have wonderful time with light coming into our windows in morning and giving us a free lightshow! Would imagines in refraction grating goes patterns to appear? Thanks for any info!

Lee Lipe
Heavenly Clowns - Paradise, California

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