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4D technology

Optics Testing

Traditionally, quality control measurements of optics are completed in tightly controlled metrology labs, with vibration isolation and extensive air flow and temperature controls.

4D Technology dynamic laser interferometers enable precision measurement right on the factory floor, without vibration isolation. 4D Twyman-Green and Fizeau interferometers allow fast, easy setup and measurement of flat and spherical optics, prisms, corner cubes and optical systems. Use the unique NanoCam Sq to measure of surface roughness on both small and large optics.

Production-oriented features and industry-leading 4Sight analysis software make it easy to test part after part, even in the presence of significant vibration and air turbulence.

Optics Testing

Astronomy Applications

4D dynamic laser interferometers play critical roles in the manufacture and testing of ground-based telescopes and space-based optical systems.

The world's premier large optics manufacturers rely on 4D systems to measure the figure and form of monolithic telescope mirrors, multi-segment mirrors and active optics.

Satellite manufacturers and integrators use 4D laser interferometers to test telescope optics and systems in cryo-vacuum environments, to align optical systems and multi-segment mirrors, and to measure the shape, and shape change, of precision structures.

Behind the scenes of every major telescope project, 4D laser interferometers ensure that hardware performs to the increasingly rigorous specifications required in leading-edge astronomy.


Aerospace Applications

Aerospace and defense contractors rely on 4D dynamic laser interferometers for accurate measurement of optics, optical systems and structures.

4D's vibration-insensitive laser interferometers play a critical role in space-based telescope programs. These systems make environmental chamber testing (at cryo-vacuum temperatures and pressures) possible, helping ensure excellent performance of satellite optics upon deployment.

At visible, near-infrared and infrared wavelengths, a 4D dynamic laser interferometer ensures reliable performance of optics for critical roles in surveillance, tracking and directed energy.


Flexible Electronics

Measuring surface roughness and quantifying the size and position of defects are critical to the successful manufacturing of flexible electronics. For commercial roll to roll (R2R) manufacturing, rapid process feedback and high areal coverage mandate that these crucial metrology operations must take place in-situ, on web platforms moving at high speeds, despite a high-vibration environment and motion of the web in relation to the measurement instruments.

The bright field inspection methods used to date can image large areas of the web, but have insufficient lateral resolution to measure fine defects. Since these are 2D techniques, they cannot quantify surface roughness even if the resolution were increased. These systems are also sensitive to reflections from the backside of the film and even the roller surface, making defect quantification and localization problematic. Off-line, three-dimensional inspection tools such as stylus systems, confocal, and interference microscopes have also been employed, but these systems are slow, sensitive to vibration, and cannot provide real time feedback as the measurement takes place after a section of film is taken from the roll and measured off-line. 



4D Technology’s FlexCam can measure roughness and quantify defects on webs up to 1 m wide with 2 μm lateral resolution, enabling real-time monitoring and control of roughness to less than 0.5 nm rms. The system provides accurate measurement without vibration isolation, despite runout and web flutter. Unlike machine-vision based systems, FlexCam is immune to reflections from the back surface and rollers effects, measuring only the texture of the top surface.



FlexCam also identifies and quantifies defects, registering their position within the roll. Defect statistics including area, volume, depth and slope are calculated, with user-selectable pass/fail criteria as each metric can have adverse effects on barrier or end device performance. Extrinsic versus intrinsic defects can be discriminated to help isolate their root cause.



Every FlexCam module provides thousands of times more areal coverage than off-line bright-field or 3D microscopes. Each FlexCam module can provide 100% inspection in the machine direction for web speeds up to 1 m/minute, and lesser sampling at higher speeds. In addition, FlexCam modules, each with over 4 mm field of view, can be arrayed across a web, offering as little or as much sampling in the transverse direction as required.

Related Products

Flexible Electronics

4D Articles and Papers

4D engineers and scientists are transforming how and where interferometers are used in research and manufacturing. Below is a selection of white papers, published articles and application notes from our 4D team.

Articles and Application Notes



Optimizing the Light Level, 2015 View PDF

Artifact Free Calibration of Spatial Carrier Interferometry, 2014 View PDF

Setting the Wedge Factor, 2014 View PDF

Snap-shot Imaging Polarimeter Performance and Applications, 2014 View PDF

Nano Surface Standards Gain Traction, 2014 View PDF

On-Screen Statistics in 4Sight Software, 2013 View PDF

Correction of Errors in Polarization Based Dynamic Phase Shifting Interferometers, 2013 View PDF

Dynamic Phase Shifting Microscope Enables Measurement of Motion of Living Cells, 2012 View PDF

Measuring Precision Telescope Optics (with a Streetcar Outside Your Door), 2012 View PDF

Dynamic phase imaging and processing of moving biological organisms, 2012 View PDF

Dynamic surface roughness profiler, 2011 View PDF

Multilayer thin-film inspection through measurements of reflection coefficients, 2011 View PDF

Dynamic phase imaging utilizing a 4-dimensional microscope system, 2011 View PDF

A pixelated polarizer-based camera for instantaneous interferometric measurements, 2011 View PDF

Extended vertical range roughness measurements in non-ideal environments, 2011 View PDF

Spatial Frequency Response and Resolution Limitations of Pixelated Mask Spatial Carrier Based Phase Shifting Interferometry, 2010 View PDF

Dynamic Interferometry for On-Machine Metrology Summary, 2010 View PDF

Noise Reduction in Dynamic Interferometry Measurements, 2010 View PDF

Pixelated Mask Extends Spatial Response, 2010 View PDF

High Throughput Measurement Speeds Production of Large Mirrors, 2010 View PDF

Measuring Wedge with the FizCam 2000, 2009 View PDF

Dual mode interferometer for measuring dynamic displacement of specular and diffuse components, 2009, View PDF

Measuring Homogeneity with the FizCam 2000, 2009 View PDF

Measuring Transmitted Wavefront Error with the FizCam 2000, 2009 View PDF

Path Matching with the FizCam 2000, 2009 View PDF

Measuring Large Mirrors With Secondary And Tertiary Support Structures, 2009 View PDF

Best Practices for Long Path Measurements, 2008 View PDF

Measuring High NA Optical Systems Without Retrace Error, 2008 View PDF

Instantaneous Phase-shift Fizeau Interferometer Utilizing a Synchronous Frequency Shift Mechanism, 2008 View PDF

Novel Interferometer Enables Challenging Measurements, 2008 View PDF

Optical Metrology for Large Telescope Optics, 2008 View PDF

Improved Interferometric Optical Testing, 2007 View PDF

Pixelated mask spatial carrier phase shifting interferometry algorithms and associated errors, 2006 View PDF

Low Coherence Vibration Insensitive Fizeau Interferometer, 2006 View PDF

Getting Rid of the Jitters, 2006 View PDF

Going Through A Phase, 2005 View PDF

Analysis of a micropolarizer array-based simultaneous phase-shifting interferometer, 2005, View PDF

Dynamic Phase-Shifting Electronic Speckle Pattern Interferometer, 2005 View PDF

Modern Approaches In Phase Measuring Interferometry, 2005 View PDF

Pixelated phase-mask dynamic interferometer, 2004 View PDF

Phase-shifting multi-wavelength dynamic interferometer, 2004 View PDF

Interferometric measurement of the vibrational characteristics of light-weight mirrors, 2004 View PDF

Vibration insensitive, interferometric measurements of mirror surface under cryogenic conditions, 2003. View PDF

Instantaneous phase shift point diffraction interferometer, 2003 View PDF

Overcoming the fringe jitters, 2003 View PDF

Figure testing of 300 mm Zerodur mirrors at Cryogenic temperatures - J.W. Baer and W.P. Lotz, 2002 View PDF

Dynamic interferometry handles vibration, 2002 View PDF

Advances in Interferometric Metrology, 2002 View PDF

Papers and Articles
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