Vacuum news

which receives the materials to be coated and contains the evaporator, is approxi- mately 1500 mm long. High vacuum pump- ing is by a 1200 litre/sec diffusion pump and this is part of a fully automatic pump- ing system which, including the high vacuum valve (NW 500), is controlled by the recently developed Vacumatic 2P pump- set controller. Cycle time is reduced by a cold trap, requiring 15 litres of liquid nitrogen as coolant. The cooling may also be performed by a 3-stage refrigerator (- 110°C) after fitting a suitable low tem- perature trap. Rapidity and simplicity of the recharging and changing operations is ensured by mounting the evaporator on a sliding carrier. Total pressures of 2x IO-” torr are measured by a combination gauge system covering the range 100 to 5x IO-* torr and having an automatic range switch. All control equipment is located in a separate cabinet of dimensions 550 x 1760 x 505 mm. Facilities are provided for the fitment of accessories such as glow dis- charge devices, dosing valves and radiation heaters. Easy access to all components is an inherent design feature, simplifying maintenance and operation. Leybold-Heraeus Ltd, UK Circle number 49 on Reader Enquiry Service card

Nude Bayard-Alpert ion gauge bead Vacuum Generators Ltd have introduced a new ion gauge head, the VIGIO. The nude type of gauge head is essential for accurate pressure measurement at a site near the experimental region. The VIGIO is of com- pact design and combines a low X-ray limit with high sensitivity. It is available on FC 38 or ocher I J-inch- (38 mm) nominal bore flanges. Risk of gauge failure during an experiment is virtually eliminated by the provision of two tungsten filaments as a standard fitting. The filaments are easily Bir- Vat TIM5 control head

TIM5 control unit

Torr Plan film thickness monitor Bir-Vat Ltd have announced the avail- ability of their new TIM5 film thickness monitor based on measurement of the change in inductance of an encapsulated coil due to the coating of a sample sub- strate with an evaporant. The sample sub- strate is a standard glass microscope slide which clips over the sensing head. Advan- tages claimed for this system over conven- tional resistance monitors include: ease of cleaning and replacement of the sample substrate; protection of the sensing head

from the evaporant eliminating costly cleaning procedures; and there is no prob- lem of connection to the evaporated film. Accuracy is within _t3 per cent full scale. In operation, the required film thickness is set by a control knob. When the indicator needle of the meter reaches the required position a relay operates to cut off the evaporation supply or to operate a shutter. The meter may then be zeroed and succes- sive films evaporated. The glass slide need only be replaced when the maximum thick- ness range of the instrument is reached. This depends on the resistivity of the evapo- rant and some typical thickness ranges are: copper, 500-8000 A; gold, 75s20,000 A; aluminium, lOO-30,000 A; and chromium, 150&100,000 A. The TIM5 control unit is a compact transistorized oscillator receiver which reacts to signals from the tuned in- ductive coil in the water-cooled sensing head. Bir-Vat Ltd, UK Circle number 48 on Reader Enquiry Service card

High vacuum coating plant The Leybold-Heraeus A.8OOH high vacuum coating plant is designed to cater for all types of coating processes on industrial scale operation. The vacuum chamber,

VIG IO ion gauge head

285