AVT Services Newsletter

Dear Viewers,

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The AVT Team

(MAPS) UHV Multi-Axis Positioning System

MDC's Multi-Axes Positioning System (MAPS) is an integrated UHV positioner combined with substrate heating. MAPS feature tilt, rotation and sample heating capability for a wide variety of substrates.

Sample tilt angle is adjustable from -180° to +180° and rotation about the sample normal is continuous. Resolution of both axes of rotation is <1.0° and speed can vary from 0.2° to 60° per second. Accuracy of positioning is provided with gear reduction in each axis.

Heating from room temperature up to 400°C is standard with an option that can heat samples to 900°C. Maps can be operated in any orientation and can be either manually driven or motorized to include motor options on either or both axes of motion with communications link for computer control. Heater controllers with PID feedback and RS232 communication are available.

Optical Coating through Solid Material Evaporation or Sputtering

By Dr. Adil Adamjee

Almost 85% of today’s optical coatings are produced using Physical Vapour Deposition (PVD) techniques such as evaporating or sputtering a solid material in vacuum onto a substrate. Assisting the deposition process by supplying additional energy through various kinds of ion-beam assisted deposition greatly improves the stability of the coatings. Sophisticated substrate rotation and control of material flow on to the substrate, as by shutters and shaped apertures, allows controlling deviations from the thin-film uniformity well below 1%. In situ monitoring of film growth via techniques such as laser endpoint detection or quartz crystal monitors, control the film thickness within a few percent of the total layer thickness.

Progress has been made in the reduction of thin-film stress or light absorption or scattering of light as well as in the control of the film-film or film-substrate interfaces by lowering the base pressures in the coating systems as well as by gaining a better understanding of the role of impurities in or additives to the material used for the coating and finally by the introduction of energy treatments of the optical films in situ or following the coating step.

As a result of continuous improvements of the PVD technologies made over the past 50 years, advanced interference coatings with an overall film thickness of up to 10µm, covering the wavelength range from UV to the far IR, are routinely achieved in production today. On the other hand equipment has become more and more sophisticated as ion sources, substrate and source temperature control, substrate movement, deposition rate monitoring, and improved vacuum systems have been added to achieve the desired process performance. Today about 50% of the cost to coat is due to the capital cost of equipment, which has risen continuously along with the quality improvements.

The only way to economically scale up production capacity is to scale the volume of the coating chamber. E.g. coaters used in the production of cold light reflectors handle more than 1000 pieces of 50mm diameter reflectors per run.

New developing markets require low cost, high quality optical coatings. For example, more than 50 years of unchanged performance is required for optical filters for use by the telecommunications market. Another example is IR-reflecting coatings for the light industry, where a high transmission of the interference stack in the visible spectrum and stable performance cycling from room temperature up to 1100°C are required. Such coatings are used in consumer products, and therefore the successful application is heavily influenced by the cost to coat.

For further information and advice on thin film coating techniques and applications please contact Dr Adil Adamjee, Thin Film Specialist, AVT Services Pty Ltd, phone: 03 9761 4318 or email: adamjee@avtservices.com.au

Watch this space for future promotions

With every newsletter AVT publishes we will be running a small promotion. November's promotion was free oil with the purchase of a new vacuum pump. This promotion is now over.