Challenge: Moisture Resilient Optical Equipment

Certain Laser & Visual systems for Man-portable, vehicle-mounted or airborne equipment that Thales manufactures consist of optical components.

These systems are used in arctic (cold) or desert (hot) or jungle (humid) environments and can be subject to large temperature fluctuations, e.g. mounted on aircraft changing altitude; desert high diurnal temperature fluctuation.

When the equipment is temperature cycled, particularly when transitioned from low temperatures to higher temperatures, water vapour condenses out onto the lenses of the optical components. 

This is due to the poor thermal conductivity of the glass relative to the surrounding equipment (which heats up faster and holds the temperature of the optics lower than the ambient temperature). This in turn results in making the glass attractive for moisture to condense onto. 

To resolve this, the standard practice is for the equipment to be sealed (using aluminium housing and covers; viton, nitrile or flourosilicone o-ring seals), filled with dry air and a desiccator included to maintain the low moisture content inside.

However, desiccators have a finite lifetime, and an imperfect box sealing can often cause some fogging on the optics with time, as the equipment ages. 

Submissions to this Challenge must be received by May 24, 2023.

Source: NineSights