Supersonic Wave Filter

The Supersonic Wave Filter ( SSWF ) is a system developed by Olympus dust reduction system. It prevents the negative effects of dust on the image sensor of digital SLR cameras. Dust and dirt particles can get into the camera body during lens changes, or by the aspiration of air during zooming. Even the smallest contaminants that adhere to the image sensor, can be seen as gray spots in the image. Olympus introduced its first digital SLR, the E-1, in 2003, the first dust protection system for D -SLRs, and has since provided all E-System cameras so. Panasonic and Leica use for their D-SLRs also the Olympus technology, other manufacturers have developed their own methods.

Protecting the sensor from dust

The hermetic seal of the space between the image sensor and SSWF prevents dust reaches the actual image sensor surface. These special rubber seals are fitted between both the image sensor and low-pass filters as well as between low-pass filter and SSWF.

Dust removal with ultrasound

Ultrasonic vibrations (35 kHz) loose on the surface of the SSWF adhering particles, which are then trapped by adhesive tape in the camera body. The SSWF is composed of a non-reflecting glass plate and a piezoelectric element. The vibrations of the SSWF caused by resonance. This is initiated by the application of an alternating voltage with a frequency of 35 KHz to the piezoelectric element. This results in bending vibration, which throw off the dust from the filter surface. Since the SSWF is completely encased in rubber, its vibrations are not transmitted to other parts of the camera.

Dust is invisible

The distance between the sensor surface and SSWF also prevents dust particles block the light incident on the sensor and are thus depicted as shadows.