Why 3D-Shape GmbH equips white light interferometers with Mikrotron cameras
How do you monitor the topography of micro parts
when the demands of efficient production require short cycle times and
high quality? 3D-Shape GmbH performs complex surface measurements using
the principle of white light interferometry, advanced sensors, 3D image
processing and powerful camera technology from Mikrotron GmbH.
Fast three-dimensional image processing
technologies are becoming more and more important for quality control of
complicated components. They are now superior to tactile measurement
systems in speed, flexibility, precision and analytical possibilities.
In keeping with the adage “a picture is worth a thousand words,” image
analysis allows you to discover complex connections and many object
parameters at a single glance.
A few years ago, high precision measurements
within industrial production lines were unimaginable. Today, reliable
quality control with measurement uncertainties of only a few nanometers
are possible even with short cycle times. This is true for applications
in the electronics, aircraft and automotive industries through to the
mold construction of micro parts with highest precision.
The Measuring Principle of White Light Interferometry
Through rapid innovation cycles in processor and
camera technology as well as in precision optics and image processing
software, interferometry is increasingly coming into focus. With white
light interferometry, the topographies of both rough and smooth objects
can be measured and captured in a very precise way. Simply put, the
measurement subject and a reference mirror are illuminated by a light
source. This is separated into two parts by a semi-transparent mirror
(beam splitter).
As the process continues, this results in
brightness variations, which are recorded on the image sensor of the
camera. These are analyzed by special software and each pixel is
assigned a height value. This then creates a highly differentiated
profile height in the nanometer range. If the process is carried out at
various layers, complex structures are recorded in their full height.
Performing High-Speed Measurements with the Highest Precision
Due to its compact design, the Korad3D system can be directly integrated into the production line.
Due to its compact design, the Korad3D system can be directly integrated into the production line.
The KORAD3D sensor product family, produced by
3D-Shape GmbH, utilizes the principle of white light interferometry.
Their ability to measure fields of 0.24 × 0.18 mm at minimum to 50 × 50
mm at maximum, means they are compact, can be integrated into the
production line systems and cover a wide range of applications. They
determine flatness and roughness on sealing surfaces, provide 3D imaging
of milling and drilling tools, give information on wear on cutting
inserts and check the period length and step height of the smallest
contacts in electronic devices. The achievable accuracy is directly
dependent on the required measurement field size, the optics used and
the camera resolution.
The most important factor
influencing the measurement accuracy and measurement speed of a KORAD3D
system is the performance of the built-in camera. Larger
measurement fields are advantageous in ensuring the system can be used
for a variety of applications. However, the greater the measurement
field, the more inaccurate the measurement. A key requirement for the
camera is therefore the megapixel resolution. This is, of course, in
addition to other important aspects of image quality such as contrast
and noise behavior and the sensitivity of the camera. At the same time,
the camera must be able to deliver a high frame rate. In many
applications, the entire structure is recorded layer-by-layer, and at
very short cycle times within the production line. Doubling the
measuring depth, however, also causes twice the measuring time. The
resulting large amounts of data need to be addressed. This can only be
achieved by a camera that captures and transfers images in real time.
Monitoring with KORAD3D in the µm Range
In order to continue processing the ball-grid
arrays without errors, it is important to ensure that they are all
placed with their top ends inside one area. The bumps in the arrays,
arranged like a “nail board,” can be checked with the KORAD3D for
different characteristics up to the µm range.
Every single contact pin in the ball-grid
array is precisely checked in size and shape to the µm range. In just
about one second, the topography of the entire group is captured.
Convincing on all Levels
When 3D-Shape were looking for a camera that
meets all these requirements best, only a few were shortlisted. The
Erlangen-based company operates along the frontier of the physically
possible and therefore needed a camera with the latest technology. They
got a crucial tip from a sensor manufacturer. According to the head of
development, ultimately the Mikrotron EoSens® was the only camera that
met all the requirements. Therefore, the company decided to equip the
KORAD3D measuring systems family with this camera.
At a full-screen resolution of 1,280 × 1,024
pixels, the camera delivers up to 500 images per second via the high
performance base/full-camera link (160/700 MB/second) interface. This
specification convinced the Erlangen-based company. So they could
monitor the as yet unfitted circuit boards at a frame rate of 180 fps
(frames per second) for a customer in the electronics industry. But even
higher frame rates of up to 500 fps are used in applications.
Another important argument for the EoSens® was
its outstanding light sensitivity of 2,500 ASA. It is based among other
things on the large area of a single pixel of 14 × 14 µm and the high
pixel fill factor of 40%. The investment required for lighting systems
was thus reduced and a higher range of brightness and contrast for image
processing could be set.
In addition to this there was the switchable
exposure optimization. It adapts the usually linear image dynamics of
the CMOS sensors to the nonlinear dynamics of the human eye at two
freely selectable levels. The bright areas are thereby suppressed and
details can be extrapolated even with extreme light-dark differences in
all areas. In the most demanding image processing tasks, this is a great
advantage.
Given the cycle times the KORAD3D system has to
maintain, each contribution to the acceleration of the data processing
is important. This includes the ROI function, which can be defined and
customized freely to fit the size and location of individual tasks or
the receptive field to be evaluated. The amounts of data are thus
reduced and the analysis is accelerated. This simultaneously allows
extremely increased frame rates. The built-in multiple ROI function
allows the user to define up to three different image fields in the
overall picture. 3D-Shape GmbH is not making use of this in current
applications, but is already looking at interesting solutions applying
this in future.
To keep the measurement accuracy of the
topographies created by the KORAD3D system in a narrow range, a number
of features of the imaging quality must work together to form a
performance-boosting whole. The global shutter of the EoSens® completely
freezes the captured frame and stores it in real time, while the next
image is already being exposed. This provides images of dynamic
processes free of distortion and smear effects. In addition to the
C-Mount lens mount there is also the F-Mount option. The latter allows
the operator to connect the camera and lens to a fixed calibrated unit,
which increases the precision of the analysis. In addition to this range
of outstanding performance data the compact design of the camera, which
simplifies system integration, wins customers over.
To Know More About Mikrotron High Speed Camera, Singapore, Contact MVAsia Infomatrix Pte Ltd at +65 6329-6431 or Email us at info@mvasiaonline.com
MV ASIA INFOMATRIX PTE LTD
3 Raffles Place, #07-01 Bharat Building,
Orchard Road
Singapore - 048617
Tel: +65 63296431
Fax: +65 63296432
Orchard Road
Singapore - 048617
Tel: +65 63296431
Fax: +65 63296432
Source - mikrotron.de
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