Practical Tips Blog

4D Technology is the world's leader in the design and development of dynamic laser interferometers, dynamic optical surface roughness profilers and polarization cameras. In this blog we share practical information for accurately measuring optics and precision surfaces in challenging environments, despite vibration and environmental noise.

Mantis Shrimp originally uploaded at by @N00_eyes.jpg
The humble mantis shrimp is considered to have the most complex eyes of any animal. Their eyes don’t just look weird from the outside—they’re weird all the way through. Each eye turns independently of the other. And each one sees in 3D. Imagine being able to see 3D views of your surroundings in two different
Laser Fizeau Interferometer
I was once in an optical metrology lab for an optical fabricator, where the large aperture Fizeau interferometers—hooded and occupying great big vibration isolation tables—were scheduled to take surface quality measurements of some custom optics that were being prepared for a customer. I was there on a photography assignment and had camera equipment and fluorescent

Quantifying Polarization

September 24, 2018 by
Polarization is a description of the orientation of a light waves propagations.
What is polarization? Polarization is the characteristic of a light wave that describes the orientations of its oscillations as it propagates through space. Light waves can be randomly polarized, linearly polarized, circularly polarized, and elliptically polarized. Light directly from the sun is unpolarized, or in other words randomly polarized, but when sunlight interacts with the
This is part of a series that supplements our webinar on PolarCam and PolarView Software One of the most active applications of Imaging Polarimeters and Polarization Cameras is measuring stress and birefringence in glass, and has multiple applications in machine vision setups. Using active illumination, typically used for in-line production measurements for birefringence, PolarCam precisely
The highly polarized state of light scattered from the corona has been known since 1871. In 1905 Schwartzchild suggested that the polarization was produced from Thompson scattering of photons by free electrons trapped along magnetic field lines. This also led to the prediction that the polarization should have radial symmetry which was confirmed by Ney
4D Technology's NanoCam Sq surface profile helped the Keck Observatory overcome a challenge of phasing mirror segments in their segmented primary mirror
Phasing mirror segments is critical to accurate observations for many of the world’s largest telescopes, which employ segmented primary mirrors. In these instruments the primary mirror consists of many hexagonal segments, rather than a single, monolithic mirror. Using segments enables fabrication of larger primary mirrors. Segments are also easier to fabricate, transport, install, and maintain.
measure turbine blade edge defects with the 4D InSpec Surface Gauge
This video shows how the 4D InSpec Surface Gauge is used to measure turbine blade edge defects. The video walks through the quick process required to measure turbine blade edge scratches and pits. The presenter shows how focus, brightness and settings can affect measurement results. Click here to view the video.
4D InSpec Feature Analysis
This video shows how to use the 4D InSpec Surface Gauge Feature Analysis to measure surface defects on precision machined surfaces. The handheld, portable 4D InSpec can measure surface defects on large or complex surfaces. The Feature Analysis automatically locates all features in the field of view based on user-input criteria. It then presents them
measure corrosion
Use and environmental exposure inevitably lead to wear and corrosion of precision surfaces. Left unchecked corrosion can impede performance and can ultimately lead to component failure, sometimes with catastrophic results. Inspectors at repair and refurbishment facilities must be able to accurately measure corrosion and determine its severity in terms of pit depth and areal coverage.
4D InSpec measuring difficult to access areas of an aircraft engine fan disk and casing. By eliminating the need for replication measurement time is reduced from over an hour to less than a minute. Images courtesy StandardAero.
When measuring surface defects on large or complex components inspectors are faced with a dilemma. High resolution measurement systems are typically confined to a stand in a metrology lab, making them unable to measure large components. These system are also too susceptible to vibration to be used on a factory floor. Handheld depth gauges afford