It is a fact of life: cameras that use interchangeable lenses are
susceptible to dust contamination because airborne dust particles
can enter the camera whenever lenses are changed.
With film-based SLR cameras,
photographers got a clean slate each time the film was advanced.
But with digital SLR cameras,
images are captured by the same sensor, over and over.
So you need to protect the image sensor -
and the low pass filter in front of it - from airborne dust.
Because even a speck of dust can ruin a photo,
and if left unattended, it can become permanently baked onto
the sensor's surface.
Professional experience and technique are
helpless in the face of physical contamination of the image sensor.
So it was with a sense of mission - and a desire to realize
the full potential of interchangeable-lens
digital SLR photography - that Olympus engineers
set out to solve the dust contamination problem.

Sumio Kawai led the team that developed the pioneering
Olympus Dust Reduction System,
and his enthusiasm for the project is evident in every word.

“In developing the Dust Reduction System,
we tested systems with all kinds of dust and
airborne particulates, including yellow dust from Central Asia,
sand from the Sahara Desert,and even ordinary table salt.
We found that particles measuring only a few hundredths of
a milimeter were most likely to affect image quality,
and although we tested a variety of approaches
that used blowers and/or wipers, none performed
the job as well as the Super Sonic Wave Filter (SSWF)
we ultimately developed.
“The SSWF system uses piezoelectric actuators to vibrate
a circular glass filter at supersonic speed,
and the round shape of the filter ensures even transmission of
vibration for more thorough cleaning action.
As the first such application of supersonic technology,
the Olympus Dust Reduction System marked
a significant breakthrough in SLR photography.
“But it wasn't an easy feat to achieve.
It's not enough for the filter to simply vibrate at
supersonic speeds - it's the speed of acceleration that is key.
And to achieve high acceleration speed requires both
high vibration frequency and a large range of movement.
So there were a lot of hurdles that had to be cleared before
the world's first Super Sonic Wave Filter could be born.”