TECHNOLOGY


METROLOGY


mobile phone market, ‘this measurement is done on the laboratory level but also in high-volume production. You can imagine, with the mobile phone industry, you get millions of lenses in one day in Asia – and we have a lot of instruments there because they have 100 per cent testing there.’ In Erichsen’s view, measuring imaging quality means measuring the system as it is. ‘We have systems to measure positioning errors of single elements in these optical systems. So we measure it from the centre and check if they are in the right position in terms of distance to the next lens, and these sorts of things, because if you are measuring imaging quality and you find it is bad, you want to know why it is bad. We have the instruments to tell what element is wrong in your complete system.’


The R&D manager points out that, with


Trioptics technology, the complete fixed system does not have to be disassembled to make these checks. The checks can also be made when an optical system is being set up in a manufacturing environment. ‘We have a lot of instruments to measure angle. It is a very robust system; it is very precise, depending on the application; and you can get lab versions. We usually do customised systems.


We also have basic instruments, but there is almost no instrument that is not adapted to customers’ needs,’ explains Erichsen. ‘We do a lot of development with a view to what the customer wants.’


What the customer wants is leading to more and


more complex and smaller optics for that mobile phone industry. Erichsen points to the increasing resolution, with phones now having eight- to 12-megapixel resolution cameras.


We do a lot of


development with a view to what the customer wants


Cameras are equally important for metrology in Ian Johnstone’s markets. Johnstone works for Armstrong Optical, and his customers use thermography cameras for examining composite structures – complex parts made of carbon fibres, set in a resin. Johnstone is applying the photonic technology of thermography cameras to quality assurance. ‘We use pulse phase lock-in, or active thermography, we input energy to the structure and then we look at the heat flow through the


material.’ Defects show up as variations in heat flow.


The user has to synchronise the image capture with the excitation energy pulse. For composites and materials of similar slow heat behaviour uncooled thermography cameras with resolution of 1,024 x 768 pixels can be used for image collection. Such systems have frame rates of several hundred hertz and are used for low-heat flow rates. For a similar analysis with ceramics and metals, which have better heat flow, the energy input travels through the structure more quickly so the frame rate has to increase, perhaps up to a 3kHz line scan rate at reduced resolution. For high frame-rate operations, thermography cameras with cooled sensors of up to 1,280 x 1,024 resolution sensors are available. Whether the material is carbon fibre or ceramic, image analysis and controller software allows the synchronisation of the energy input sequence with the collection of the sequence of thermal images and the subsequent deconvolution of the data presentation of the results. ‘Big areas can be measured fairly quickly with active thermography, and it will show you where the defects are. Depending on the structure thickness and size of the defect, it may also


➤


Photomultipliers from ET Enterprises and ADIT Electron Tubes


Need to detect light down to single photon level? Need dark counts as low as a few cps without cooling? Need a detection area of up to 200cm2 or more?


If the answer is yes to any of these questions, then ET Enterprises, and sister company ADIT Electron Tubes in the US, may have the answer with their range of photomultipliers and associated electronics and hardware.


Photomultipliers have always offered significant performance advantages over other types of low-level light detection devices and this is as true today as ever before. But what has changed is that photomultipliers are now much easier to use due to the wide range of ready-to-use associated electronics and HV supplies, and modular analogue and photon counting systems, in many cases operating from low voltage.


ET Enterprises Limited, Riverside Way, Uxbridge, UB8 2YF, UK Phone: +44 (0)1895 200880 Fax: +44 (0)1895 270873 sales@et-enterprises.com www.et-enterprises.com


www.electrooptics.com


compact, and low power integral HV bases And, of course, we can also supply the photomultipliers for


.


ADIT Electron Tubes, 300 Crane Street, Sweetwater, Texas 79556, USA Phone: (325) 235 1418 Fax: (325) 235 2872 sales@electrontubes.com www.electrontubes.com


....


your application. We offer a very wide range, including alternatives to many Photonis types.


Visit us at Photonics West, February 2-7, 2013 San Francisco, Booth 1738


FEBRUARY 2013 l ELECTRO OPTICS 23 catch the light


Examples of how we can make using photomultipliers easier:


Sockets and voltage dividers for almost any photomultiplier type and application


Magnetic shields


Modular signal processing electronics, analogue HV power supplies, including bench-top and Light-tight housings including cooling.


or digital


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