Case Study 9

Standard Versus Non-Browning: what should you consider before selecting a lens for an application subject to radiation

Selecting a Lens
With the exception of fused silica or quartz all standard ‘lower cost’ UV-visible glasses react to gamma, neutron and x-ray radiation by turning dark. This means that if you are using a standard lens in areas where there is radiation in weeks or a few months you will lose your image. As a consequence – you will have regular camera / sensor downtime, lens replacement costs, irradiated lens disposal costs and the need to enter the radiation zone to make the lens replacement.

The widely-accepted solution to this is to use non-browning glasses that have Cerium Oxide added which retards the darkening of the glass when exposed to radiation. However, be aware, in highly radioactive environments, even non-browning glass types will darken slightly over time.

Compared to the considerable global requirement for UV-visible lenses the market for lenses that will withstand radiation is comparatively small. As a consequence – non-browning lenses are typically manufactured in smaller batches to order and compared to standard ‘off-the-shelf’ UV-visible optics are more expensive to initially purchase.

However, before making your choice of lens factor in the cost of the manpower required to regularly change standard lenses, the cost of the plant shut down and the cost of dealing with the old lenses which may now be considered to be radioactive waste.

A non-browning lens will continue to work until it has exceeded its accumulative dose of radiation. In the case of Resolve Optics non-browning lenses they are rated for 100,000,000 rads so depending on the level of radiation they are exposed to daily you could expect the lens to have a life of around 10 years.

While Resolve Optics is renowned worldwide for supplying fixed focus and zoom non-browning lenses for applications in nuclear reprocessing and power generation – today our expertise is helping organisations operating in a growing number of different and interesting applications subject to gamma, neutron and x-ray radiation.

In medical research – Resolve Optics radiation resistant lenses form the targeting elements in synchrotron radiation therapy machines and also in commercial x-ray instrumentation. In outer space all instrumentation, sensors and cameras are subject to constant bombardment by radiation that will quickly degrade and make inoperative standard optical components. Space borne applications present a challenging environment, subject to radiation, where camera lens servicing or replacement is highly undesirable. Recently a major space agency selected Resolve Optics to supply them with a selection of high performance, radiation tolerant zoom lenses because of our expertise in this area and willingness to work with them on adapting our standard 3x and 6x non- browning zoom lens designs to be ‘space ready’.

To discuss your application subject to radiation please contact us on +44-1494-777100 or sales@resolveoptics.com.