Caeleste News

Patent “Enhanced dynamic range imaging” granted

US patent US10.497.737 entitled “enhanced dynamic range imaging” was granted on Dec 3, 2019.

It describes a pixel and methods to reach a very high dynamic range (HDR) by integrating the same photo charge on multiple capacitors synchronously.  The concept reminds other Caeleste HDR methods (patents US9.780.138, US9.699.398, US9.819.882, BE1023468), yet uses a conceptually different approach.



Creative Collaboration resulted in a new paradigm in neural recording

Our expertise on low noise readout circuits lead to the collaboration with the Californian med-tech startup Paradromics. Caeleste developed a Read-Out Integrated Circuit system for a neural sensor which has an extremely challenging noise requirement to be able to read the neuron potentials. This is where our passion for technological challenges and craftsmanship was crucial for the success of the sensor development. Read the full article here:

Crane needed to move climate chamber into the Caeleste characterization lab.

We know what matters for our tests: reliable, precise and reproducible results. When testing sensors, you must adhere to numerous test standards and carry out long-term tests.

The LabEvent T/210/70/3 (WeissTechnik) climate chamber allows to cool or heat the environment down to -70°C or up to +180°C. To avoid condensation and formation of ice, nitrogen is flushed.   It can contain setups or instruments as large as 630x560x570 mm.


Caeleste will be presenting three papers at CMOS Image Sensors Workshop – Toulouse 26 & 27 November 2019

At the annual “Space & Scientific CMOS Image Sensors” workhop, Toulouse on November 26th and 27th 2019, Caeleste will present three papers.  A fourth paper where Caeleste is co-author is presented by CSEM.  The Toulouse workshop is considered as the most prominent space image sensor conference in Europe.

The slides will be made available on this website after the workshop.


1. A rad-hard, global shutter, true HDR, backside illuminated image sensor

by B.Dierickx1, A. Kalgi1, D. Van Aken1, A. Klekachev1, J. Basteleus1, P. Stampoglis1, G. Di Nicolantinio2, F. Palumbi2, A. Pelamatti3 of 1Caeleste, 2LFoundry, and 3Airbus

The ELFIS (ESA contract 4000116089) is the first image sensor that combines following properties: True HDR or “MAF HDR” (Motion Artifact Free High Dynamic Range), IWR Global shutter using GS CMOS technology, BSI (Backside illumination) and TID (total ionizing dose) radiation hard design. It has 1920×1024 pixels on a 15µm pitch.  We will describe the design, the measured key performance parameters and show recorded movies demonstrating the high dynamic range (96dB) while operating in IWR global shutter.

See also previous posts: movie and white paper.

2. Hyperspectral CMOS BSI Image sensor

By Deepraj Gautam1, Qiang Yao1, Dirk van Aken1, Bart Dierickx1, Bert Luyssaert1, Wei Wang1, Dirk Uwaerts1, Koen Liekens1, Gaozhan Cai1, Kyriaki Minoglou2, Arnaud Bourdoux3, Dominique Baudoux3, Vincent Moreau4, Eric Callut5, Julien Nuttin5 of Caeleste (1), ESA (2), (3) Spacebel, (4) AMOS, (5) Deltatec

The “Enhanced Light Offner Image Sensor” (ELOIS) is a 2048 x 256 hyperspectral CMOS BSI image sensor, developed with the support of the European Space Agency. The sensor has a broad spectral range from 400nm to 1000nm. The pixel size is 15.5 x 15.5 µm2. The peak quantum efficiency is 95%. The full well capacity of one pixel can be programmed between 40ke- and 200ke-.  Pixels can be 4×1 binned.

Proton damage resilient pixels

An interesting feature of ELOIS is its “proton resilient” pixel. Groups of 4×1 (sub-)pixels can be binned in two ways. In charge domain binning, floating diffusions are shunted, and the charge is averaged.  In voltage domain binning the source follower sources are shunted, acting as analog “maximum operator”.

3. Optimized ASIC Development for Space Large Format NIR/SWIR Detector Array

by Peng Gao, Andrew Keefe, Bart Dierickx, Qiang Yao, Wei Wang, Tim Morlion*, Bert Van Thielen*, Ramses Valvekens* of Caeleste, Mechelen, Belgium and *EASICS, Leuven, Belgium

We describe the design of a universal, radhard, cryogenic, low power, interfacing ASIC for space-based, large format NIR/SWIR detector arrays.  This device is designed for 50krad (TID) ionizing radiation and tolerant for SEE. Planned operation temperature is between 35 and 77 Kelvin.

4. Results of microlens testing on back-illuminated sensors for space

by F. Zanella1, G. Basset1, C. Schneider1, A. Luu-Dinh1, I. Marozau2, S. Fricke1, A. Madrigal2, D. Van Aken3, M. Zahir4, of CSEM(1,2) , CAELESTE(3) and ESTEC (4)

CSEM will present a paper reporting an activity one the design, manufacture and test of microlenses on a back thinned CMOS image sensor under space environment conditions. The validation had to address the microlens technology, its design, materials and involved processes.  The image sensor employed was the ELOIS, presented in paper no.2, listed above.


Caeleste welcomed students and professors from TsingHua University

Four professors and nine students (under the leadership of prof. Feng) from Tsinghua University (THU) visited Caeleste on 21 August. We had an informal workshop on electronic design research. The TSU students presented work on high-speed SAR ADC, Delta-Sigma modula tor, millimeter-wave CMOS amplifiers and frequency synthesizer for NB-IoT application. Caeleste designers presented work on photon-to-photon image sensor operation and neuron probing.

THU is ranked as the best engineering and computer science school in the world

ELFIS first “true HDR” movie

This is a follow-up of the new sitem of April 2019 on ELFIS first true HDR image
The ELFIS imager is the first image sensor ever combining following features:

  1. True HDR or “MAF HDR”, motion artifact free HDR
  2. Global shutter using GS technology,
    • Allowing low noise CDS readout
    • Enabling Global Shutter (IWR) without dark current penalty
  3. Backside illumination
  4. TDI radiation hard design

It is developed under ESA contract 4000116089 “European Low Flux Image Sensor”, in collaboration with LFoundry (I) and Airbus (F)
Read more…

Movie: The first “true” HDR movie made with the ELFIS sensor.

This movie demonstrates HDR in combination with true global shutter: the rotating black ring “cuts through” the dark interior background as well as through the sunlit outside background. The motion blur is not affected by the local light intensity.
The two upper frames are the HG (high gain) and LG (low gain) sub-frames as recorded
The bottom frame is the resulting HDR movie.
The movie is recorded under following conditions:

  • IWR tframe=tint = 30ms thus fframe=33Hz
  • Looking through the lab’s window to sunlit buildings in the Michiel Coxystraat
  • Nikon 28mm lens, diaphragm set to 22 ( sic! this is a 15µm BSI pixel!)
  • On-chip CDS and dark frame subtraction
  • No PRNU correction, no linearization was done. Two defect rows were corrected
  • The HDR image is created by a weighted interpolation between the HG and the LG frames
  • The image is “histogram equalized” for display.

Patent US10284824 granted

Patent US10284824, filed 2017 Jan 22, was granted on 2019 May 7. It describes and protects a concept to break the data volume barrier as we encounter it in ultra-high-speed image sensors. Aggregated pixel rates nowadays exceed 10 Gigapixels/second and require a very high number of parallel electrical channels. Further increase with the present state of the art requires an even higher degree of parallelism, which soon becomes unrealistic.
Caeleste’s concept avoids the huge electrical parallelism. Data are output through an extra “photonic layer”, 3D-integrated below the image sensor IC. This layer interfaces directly with fiber optic transmission lines.
You can download the patent from here.

The patent idea was previously presented at IS Americas, from which the presentation can be found here.

Two Caeleste papers at IISW 2019

At the International Image Sensor Workshop, June 2019, Utah, USA, Caeleste will present two papers on advanced CMOS image sensors.

Peng Gao, design team leader at Caeleste will present the paper

“16.7Mpixel 8000fps sparse binarized scientific image sensor”

by Peng Gao, Sampsa Veijalainen, Jente Basteleus, Gaozhan Cai, Bert Luyssaert and Bart Dierickx

This is a large format (36.1×40.2 mm2), 4K x 4K CMOS image sensor, having single-bit binary pixels on a 8µm pitch.  By the use of a proprietary readout technique it reaches frame rates up to 8000fps in sparse mode.


Annotated photograph of the image sensor

Ajit Kalgi, design team leader at Caeleste, will present the paper

“Fast Charge Transfer in 100µm long PPD Pixels”

by Ajit Kumar Kalgi, Arne Crouwels, Bart Dierickx, Walter Verbruggen and Dirk Van Aken

In this paper we present a patented photodiode structure for fast charge transfer in elongated pixels. For applications requiring high frame rate and elongated pixels, charge diffusion in photodiode limits the transfer efficiency, thus ultimate frame rate. We solve this by creating electrostatic potential gradient in the elongate direction by exploiting the effect of proximity of implanted regions on the pinning voltage.

Measured diffusion time using or not using the technique.

ELFIS first true HDR image

The ELFIS imager is the first image sensor ever combining following features:

  1. True HDR (“MAF HDR”, motion artifact free HDR)
  2. Global shutter using GS technology,
    1. Allowing low noise CDS readout
    2. Enabling Global Shutter (IWR) without dark current penalty
  3. Backside illumination
  4. TDI radiation hard design

It is developed under ESA contract 4000116089 “European Low Flux Image Sensor”, in collaboration with LFoundry (I) and Airbus (F).

The first “true” HDR image of the ELFIS sensor.
Figure: The first “true” HDR image of the ELFIS sensor.

The above image is taken under following conditions

  • Looking through the lab’s window to sunlit buildings at the other side of the street
  • Nikon 55mm lens, diaphragm set to 22 (!)
  • IWR tframe=tint = 30ms
  • On-chip CDS and dark frame subtraction
  • No PRNU correction, no linearization, no bad pixel correction, no other cosmetic corrections.
  • The HDR image is created by a simple threshold at 80% of the HG saturation.
  • The image is “histogram equalized”

Read more