Tech Briefs Magazine - May 2023 - PIT-13

convex, or cylindrical. They can be made
from several hundred common glasses or
from complex materials such as fused silica
or calcium fluoride.
Flat, or plano optics, involve a range of
optical components with flat, parallel surfaces
with very little wedge. A plane mirror
used to redirect light along an optical
path, for example, is critical for applications
involving images or large beam sizes
because variations can alter the reflected
wavefront and increase image distortion.
For many laser applications, the optical
components must be flat and parallel,
with a polished finish devoid of
surface damage to avoid misdirecting or
scattering the light.
To achieve the precise wedge or parallelism,
the components must be precisely
ground and finished to extremely
tight dimensional tolerances.
Fortunately, advanced, automated
rotary surface grinders offer advanced
sensors and controls that can precisely
direct the grinding process to achieve
the required specifications in much
less time, to ensure optimal component
quality and performance. The advanced
grinding equipment may also significantly
reduce intermediate lapping steps and
the risk of breakage of high-value optical
components, further reducing costs.
Advanced Rotary Surface
Grinders
According to a principal optical manufacturing
engineer in the photonics
industry, grinding is the first step toward
creating optical glass with the required
size and surface for high-quality,
photonics parts.
To achieve this, photonics materials are
ground down from stock material of varying
size, shape, and thickness. After optical
components are initially ground to
remove significant amounts of material to
get close to the specified size, each component
is further refined. Finer grinding
and polishing is performed to reach precise
dimensions, tight tolerances, and a final
finish - which can be challenging with
older conventional grinders.
" In optics, you start with a surface
grinder to get down to microns; when
you finish lapping and polishing the optics,
you are in the range of nanometers.
At that point, the photonics parts should
perform optically and interferometrically,
allowing measurement using the
phenomenon of light wave interference
as expected, " says the photonics industry
optical manufacturing engineer.
Photonics & Imaging Technology, May 2023
With advanced sensors and controls, an automated surface grinder can remove material down to
within one ten-thousandth of an inch of the final thickness. (Image: DCM Tech)
Advanced automated rotary surface grinders may significantly reduce intermediate lapping steps and
the risk of breakage of high-value optical components. (Image: DCM Tech)
With rotary table surface grinders, the
table rotates with the workpiece held
firmly in place underneath a vertical
spindle. With this approach, the grinding
is not performed by the peripheral
edge of the wheel, but rather by the entire
diameter of the abrasive surface.
Traditional rotary surface grinders
can lack accuracy and reliability in the
hands of less experienced operators.
With limited control of spindle speeds
as well as manual controls, the older
equipment requires sophisticated operators
with a subtle touch, who can
also make complex calculations. Considerable
expertise and experience are
required, which can be a challenge as
skilled operators retire.
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Tech Briefs Magazine - May 2023

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