An Introduction to Zygo Metrology Solutions for improving product quality and reducing cost
The Zygo Metrology Group at Lambda Photometrics delivers precision industrial metrology solutions for QA and Statistical Process Control in manufacturing to help reduce the cost of defects and ensure your customers receive the best possible engineered components. Non-contact metrology from Zygo for manufacturing and R&D provides you with the tools to do the job quickly and effectively whilst providing the flexibility to adapt to your needs as your customers demands change. At Lambda Photometrics we recognise that our customers are faced with growing pressure to improve the surface form, finish and performance of components they manufacture and we have developed leading edge metrology solutions to help deliver such capabilities to you. Our high speed and precision metrology tools are capable of measuring: 3D surface profiles, roughness, texture and machining marks, step height, features, cone angles, wear volume, flatness, surface form, radius of curvature and many other parameters associated with precision engineered components, optics and MEMS (micro-electro-mechanical systems).
A wide range of industry sectors including automotive, medical, optics, IT, semiconductor, aerospace and precision engineering have benefited from working with Lambda Photometrics:
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If you have a pressing metrology issue and would like to know if we can help, try us out and send us a component sample to be measured, for more details see our sample measurement programme
What we measure
Precision metrology for a wide range of surfaces and in some cases films encountered in engineering and science. Our solutions allow surface profiles, form, flatness, waviness, texture, roughness, machining marks, material features and finish to be measured using high speed non-contact imaging technology. This delivers:
- Non-contact measurement of complete surfaces in 3D not just point samples or a line profile but height information across a whole 2D image so you do not miss a thing
- Powerful process software with easy to use interface allows you to extract familiar data such as 2D profiles at will and in any orientation
- Capture data at far higher speeds than can be achieved with contact methods such as CMM or stylus profilers. Up to a million data points can be captured in seconds
- To rapidly take the 3D data captured and allow comparison with conventional contact metrology
- Offer far higher precision particularly in the height dimension than can be achieved with conventional metrology tools, typically down to 0.1nm
- Allow complex image processing of data to perform sophisticated QA measurements or extract specific quantitative data from the measurement e.g wear volume
- Automate the process to reduce or eliminate operator intervention
- Provide rapid measurement of serial components for factory floor 100% inspection
Typical measurements:
- Surface form and profile
- Departure from spherical and planar form
- Flatness
- Radius of curvature measurement for concave and convex surfaces
- Volumetric wear
- Surface features and machining marks
- Roughness and a wide range of texture measurements for surfaces including Ra, Rpm, Rz (conforms to new ISO standards). For a full list of measurements download this document Texture
- Waviness and a wide range of parameters user selectable through filters
- Cone angle and recessed features
- Step height and multiple surfaces
- Thin and thick films
Traceability to certified standards
Our metrology tools provide unrivalled performance that is traceable to certified standards to ensure you achieve the highest accuracy, reproductibility and repeatability in your application. For more details download this document standards measurement.
| Industry | Typical Application |
| Automotive | Test inspection of diesel injectors & valve seats |
| Data Storage | Measurement of magnetic read/write heads for hard disk drives |
| Dynamic MEMS | Measure motion, displacement & key device parameters |
| Medical | Measure surface roughness and wear patterns of orthopedic implants |
| Optics | Flatness measurement of ultra-precision optics |
| Pharmaceutical | QA of pill & capsual surfaces |
| Semiconductor | Measurement of semiconductor package interconnects, solder bumps and micro vias |
Other typical applications include:
Orthopaedic implants
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Contact Lenses
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Diesel Injectors
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MEMS - Micro Electro Mechanical Systems
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Data storage
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The tools we use
The GPI, is a Fizeau type interferometer system coupled to an electronic camera and computer system for control and image processing.
- Non-contact high speed imaging metrology tool
- Surface form, flatness and measurement of spherical components (both convex and concave)
- Measures deviation from form of a complete surface area typically from several sq cm to hundreds of sq cm in seconds
- Measurement is guaranteed to better than λ/10 (63nm) across the whole viewing aperture of the instrument, the resolution of the instrument is far higher. Higher performance to better than λ/100 (6.3nm)has been demonstrated in some applications
- Radius of curvature of both convex and concave components to several microns
- Simple user interface for fast and easy measurement even by unskilled operators
- Can be automated and placed in protective housing for production and shop floor environments
- Built in environmental noise monitoring
The NewView, a scanning white light interferometer system incorporating a microscope objective lens, led light source, electronic camera and computer system for control and image processing
- Non-contact imaging metrology tool, captures up to a million 3D surface data points at high speed
- Measures roughness, texture, flatness, surface height, feature dimensions and thin films with unprecedented performance over conventional metrology tools
- Wide range of built in Roughness parameters from Ra to Rz and other texture parameters
- Typically measures sub sq mm to several sq cm
- Repeatable surface height measurement to 0.1nm
- Ability to measure film thickness, typically from 1 to 75 microns
- Wide range of accessories that also allow measurement of difficult recessed or concave components and features (using super long working distance objectives)
- Simple user interface embedded with powerful metrology applications for rapid and easy measurement
- Can be automated and placed in dedicated protective enclosure for application on factory and shop floor environments
- Built in environmental noise monitoring
How they work
There are two components to the metrology tools we provide, the hardware, comprising the instrument with PC and frame grabber and the software that controls and processes the data from the system. The combination of hardware and software provides fast and powerful metrology tools that deliver automated measurement solutions for QA and R&D in a fast and flexible way.
We use and supply two key instruments, the GPI and the NewView, for surface and profile measurement both driven by a common software package known as MetroPro. Both instruments are non-contact interferometric imagers that provide a 3D image of a surface to a very high degree of precision and with very high speed compared with conventional mechanical systems. Both provide a snap shot of the surface which when processed by the software allows you to extract a wide variety of parameters about a surface including making comparison with conventional measurement techniques. In the case of manufacturing this allows for automation and 100% inspection of components. For R&D the fast turnaround coupled to an easy to use interface makes productivity and metrology fast and accurate and with a precision far above mechanical methods this allows you to explore future capabilities and options.
The GPI interferometer comprises a laser light source, optics for focussing, expanding and collimating the beam and a camera for recording interference fringes. The GPI can be used for measuring flatness using a precision Transmission Flat or spherical surfaces using a Transmission Sphere, in this particular example we shall consider the measurement of a spherical surface. The Transmission Sphere used for this measurement is a focussing lens taking the collimated (flat wavefront) laser beam and focussing it into spherical waves that converge onto the part to be measured. The transmission sphere is a precisely formed system of optics that for most applications can be considered to generate a perfect spherical light wave converging on the part under measurement.
GPI Basic Operation
Some of the collimated light on striking the curved surface of the transmission sphere (a glass/air interface) is reflected back into the instrument to create a reference beam of light. In this example a spherical sample has been placed in proximity to the Transmission Sphere such that the spherical wavefronts impinging on the surface strike the surface at a normal and hence the light is reflected back along its original path and into the instrument. The reflected light from the part under measurement and the reference beam are combined to create an interference pattern that is detected by the camera.
During a measurement the Transmission Sphere is translated linearly along the optical axis with a piezo electric device to create a moving fringe pattern that is interpreted by the computer system to show the deviation of the part under test from an almost perfect sphere. The system displays these departures from spherical form using a colour coded image plot and also an oblique surface form plot, click here for examples of a spherical hip socket. The same principles can also be applied to the measurement of flat surfaces using a Transmission Flat as the reference.
The NewView scanning white light interferometer has similar elements and operation to the GPI. It employs optics in the form of a modified microscope objective, a light source, in this case an incoherent broadband LED light source is split at the objective so that some of the light passes to a reference mirror and some is focussed onto the surface of the sample under measurement. Light from the mirror and the sample surface are reflected back into the instrument and imaged onto a camera. If the distance from the light splitter to the mirror and from the splitter to the surface are equidistant so that there is no optical path difference (OPD) then the camera will observe an interference pattern. This occurs when the objective is held so that the focal plane of the objective lies in the same plane as the surface.
NewView Basic Operation
In order to perform a measurement of the surface observed by the field of view of the objective, the objective lens is translated vertically and linearly so that the focal plane moves through the entire height range of the surface being measured. As it does so the interference fringes will move and follow the height profile of the surface and this information is processed by the instrument to calculate the height profile to a very high precision. If we take the simple example of a spherical surface and the objective moving downwards then the interference fringes will appear as a small set of concentric circles emanating from the top of the sphere as the focal plane of the objective intersects it.
The concentric fringes will then grow larger as the focal plane moves and intersects the sphere lower down. The NewView is able to measure and view an image field dictated by the field of view of the objective lens, for example a 10x objective with a resolution of 1.18 microns is able to observe an area of 1.1mmx1.1mm. As with the GPI the MetroPro software processes the interference data to create a colour coded height profile of the surface under measurement, click her for an example, To measure larger areas there is a facility on the NewView to stitch image fields together. A motor driven stage allows the system to move the surface under inspection a step at a time and in raster fashion to allow relatively large planar surfaces to be measured.
Metricon’s 2010/M instrument measures thickness and refractive index of thin films (~0.4 to 50 microns) using a prism coupling technique. It can also measure bulk refractive index at a number of specific laser wavelengths to yield Abbe Number and dispersion information. In addition measurement of liquids, polymers, waveguide loss, dual films and many more sample types is possible. For more information click here.
From M³ Measurement Solutions, we offer a measurement service for characterising refractive index, dispersion and dn/dT of optical materials.
