Caeleste News

Caeleste team wins second edition of Electroniad

After having organized the first Electroniad ever in 2016, the Caeleste members could proof
their electronics skills on the second edition of the Electroniad, organized by Easics
on 14 September 2017 in Leuven.

The Team Caeleste_Plan_C consisting of Periklis Stampoglis, Ahmed Abdelmodeem, Nick Witvrouwen en Walter Verbruggen won this year’s contest.

The third edition of the Electroniad will be organized by Ansem in October 2018.

Two new representatives to shorten the communication lines

Caeleste appointed 2 new representatives to support its presence in the image sensor market and to have shorter communication lines with our customers. We welcome Kerry Van Iseghem to strengthen the US team and Ian Alderton of Alrad to deal with UK and Irish customers.

Kerry Van Iseghem is a well-known person in the American image sensing community. Kerry graduated from the University of Rochester (the US capital of imaging) and was professionally active there. Kerry spent his whole professional life in the semiconductor industry; since 1998 his main interests were in image sensing solutions. Most people will remember him as the founder and CEO of the Imaging Solutions Group, where he was building advanced camera systems. Since October 2017 he is valorizing his experience with image sensors and imaging applications exclusively for the Caeleste customer bases.


Caeleste is also proud to announce that Alrad of Newbury, Berkshire, will represent Caeleste in the United Kingdom and Ireland.

Alrad is already in business since 1970, offering customers state-of-the-art imaging solution even long before the era of integrated detector arrays. Due to their experience in the field, they have continuously explored new horizons and they stay at the forefront of electro-optics developments.

Ian Alderton, CTO and sales manager, will mainly support Caeleste customers. Besides his activities within Alrad, Ian is also member of the board of PPMA, the British Vision Association.

Michele d’Urbino won best student paper award at A-SSCC, Seoul

Michele d’Urbino won the best student paper award on the Asian IEEE conference for Solid-State Circuits (A-SSCC). The title of the paper is ‘An Element-Matched Band-Pass Delta-Sigma ADC for Ultrasound Imaging’.

We herewith congratulate Michele and the co-authors of the TU Delft for their outstanding performance.

The full paper can also be downloaded from the Caeleste website.


Gaozhan Cai invited speaker at Image Sensor America Conference

Gaozhan Cai was invited speaker on the Image Sensor Americas in San Francisco in October 2017. He presented a paper about his work in the field of all optical image sensors or with other words and image sensor converting ‘photons to photons’.

By using heterogeneous integration techniques it is possible to combine an image sensor layer with an electrical signal processing layer and a photonic IC for the interfacing of the image sensor with the external world. In this way a complex image sensor can be realized with much less contacts and also the power dissipation in the device itself is lower due to the use of optical light modulation. The full paper can also be downloaded from the Caeleste website.

Ajit Kumar Kalgi best under 35 presenter at AITA 2017

The Caeleste presentation about: ‘Multiple shutter mode radiation hard IR detector ROIC’ was selected for Oral presentation during the prestigious workshop Advanced Infrared Technology and Applications (AITA 2017), held at the Laval University in Quebec. With this contribution Ajit won the best contribution prize for authors under the age of 35.

Quebec City is considered the capital of electro-optics in Canada. With the Laval University,
the independent R&D center INO (Institut National d’Optique) and several industrial (space) companies in the neighborhood, this area has top class researchers in the field of infrared imaging and its applications.

The paper describes Caeleste’s achievements to realize a highly programmable low noise ROIC (readout IC) for hybrid low-flux, long wavelength infrared detectors for astronomical applications in space. The circuit is realized, using Caeleste’s radhard library and fulfills all requirements set forth by the European Space Agency. In a later contribution we will report on the electro-optical performance evaluation by the University of Cardiff (UK) of the hybrid assembly with AIM’s (Germany) long wavelength HgCdTe detectors.

The paper is available on our website.

Ajit Kumar Kalgi (left) won the best contribution prize for authors under the age of 35.

Caeleste was granted a new patent about pixels with increased storage

On July 4th 2017 Caeleste was granted a new patent CMOS image sensor pixels with high charge storage capacity. As image sensor pixels become smaller and smaller, the charge contained within the pixel also becomes smaller, resulting in a lower Signal to Noise Ratio (SNR) of the Pixel. Caeleste is pioneering since a long time High Dynamic Range or HDR pixels combining a high storage capacity with low noise. Caeleste has several patents on high dynamic range and global shutter pending or granted.

The complete text of this patent and other Caeleste patents is available on our website.

Caeleste at Photonics West

Caeleste is present at Photonics West in San Francisco.
With all your questions about imaging solutions and photonics integration solution, you can contact the onsite Caeleste team:

Jan Vermeiren, Business Development Manager
Eiji Watanabe, US account manager
Kerry van Iseghem, Marketing and Sales Manager North America

You can find the Caeleste team
in the North Hall of the Moscone Center at booth 4222.

Caeleste presents image sensor with in-pixel very high linear dynamic range

From May 30 until June 2, Caeleste participated in the International Image Sensor Workshop (IISW), organized by the International Image Sensor Society. The workshop was held in Hiroshima. Caeleste presented an image sensor with an in-pixel very high linear dynamic range.

A method to increase DR using column-level automatic gain selection

Image sensors have to cope with a very high dynamic range of the captured scenes. Objects in the shadow during a noon summer day in summer, can have quite often an intensity, which is 100 000 less than the brightest parts. In night vision automotive applications, the difference can be even larger: the signal of a pedestrian behind the high beams of a car can be 10 million times less than the lights of the car or the street lights. Also in spectroscopy for medical and remote sensing, the dynamic range can be very large as the spectrum of a lamp or the sun varies greatly as a function of wavelengths. Also in stimulated emission imaging as Raman or fluorescence the signal levels can vary with several orders.
As most analog systems, image sensors have a dynamic range in the order of 60 to 80 dB.  Several methods exist to increase this dynamic range as eg the capture of a sequence of pictures with different integration times of sensitivities; these images can then be combined in software to yield a high Dynamic range image.

But for fast moving objects it is very important that the utilized method does not introduce motion induced artefacts as can be the case in the above example. In the IISW workshop Gaozhan Cai, Senior Design Engineer at Caeleste presented an image sensor with an in-pixel very high linear dynamic range (HDR) that is obtained by a unique method where in the pixel a three level transfer gate is used combined with a dual or triple gain charge storage and where a column-level automatic gain selection (AGS) is implemented. The AGS picks one out of three linear ranges each having a largely different conversion gain. The data rate remains the same as without high dynamic range, thus preserving the maximal frame rate.

For fast moving objects it is very important that the utilized method does not introduce motion induced artefacts

An example of high dynamic range image processing is shown below: The raw image (in medium gain setting) is shown over the left. Some parts of the image are clearly over illuminated while others are under illuminated. In the middle part the segmented image is shown, where the gain setting for each of the image is indicated; the rightmost image is the HDR images where the different gain images are combined and the image content compressed to fit in the display range.

How to hand-calculate MTF in frontside and backside illuminated image sensors

The spatial resolution of a camera and in general an imaging system is one of the key performance parameters apart from the temporal pixel noise. It determines which small objects can still be separated by the system. Not only the lens is limiting the spatial resolution, also the image sensor is limiting the image resolution. The macroscopic crosstalk, which is at the basis of the resolution reduction, has several components, which require complicated modeling taking into account the pixel geometry and the material properties. Prior models for this resolution or MTF prediction were based on ‘brute force’ solving the diffusion equations in a finite elements mesh detailing the pixel’s geometry.

Bart has now proposed a closed-form analytical MTF-nyquist model, being suitable for integration in a spreadsheet-like calculator, enabling thus quick surveys and design parameter trade-offs in the presence of many other image sensor parameters. The method yields an analytical expression for the Line Spread Function as intermediate result. In this way much faster system optimizations can be made.


Idealized pixel cross section as used in the model, and the analytical expression for the distribution of electrons as arriving at the collection photodiodes