Most recent digital camera and imaging news items - RSSDigital camera and imaging news items - HTML

DALSA sensors show near and far photo images

Triggered by the battle of the giants with the recent announcements of the 50+ megapixel medium format digital cameras, we at DCViews have been invited for a visit to the DALSA Image Sensors Business in Eindhoven, the Netherlands.
As you will have noticed in the news releases, DALSA's 6 micron sensors are playing a major role in the digital medium format camera market. Our visit also revealed that DALSA is active in many more markets, and most of you will - unknowingly - have been looking at images created by DALSA sensors. Here's our story...

A closer look at the DALSA Image Sensors and Business

High Tech Campus - Natural parkingIt's a drizzly Tuesday morning when we arrive at the High Tech Campus, a hotspot for innovation in Eindhoven - the Netherlands, where we can easily park our car in one of the natural parking garages. The visit today has been triggered by the recent announcements of the PhaseOne P65+ and the Leaf AFi 10 medium format digital cameras with their innovative high resolution image sensors; the DALSA Image Sensors Business division turned out the place to be.

Jan Bosiers (left) and John GommansWe are welcomed by John Gommans (Director and Product Manager), Jan Bosiers (R&D director) and Bas van Houtum (Director of Industrial Operations). John kicks-off our session with a short history and background of the current operation. Back in April 2002, the former Image Sensors Business of Royal Philips had been acquired by DALSA and the Image Sensor division now has the overall responsibility for research, development and manufacturing of the DALSA image sensors. The wafers that are used in the image sensors are produced at the waferfab in Bromont, Canada, a production facility acquired by DALSA in 2002 too.

Today, the DALSA Corporation is essentially built on three pillars, Digital Cinema, Digital Imaging, and Semiconductors; they offer a broad product range including image sensors and image sensor components, electronic digital cameras, vision processing hardware components, image processing software algorithms, and semiconductor wafer foundry services.

Digital Imaging

The Machine Vision products are used for quality inspections of semiconductors, printed circuits etc. Another challenging application is for postal & parcel inspection systems where an image of an entire address (even handwritten) must be lifted from letters, magazines, and parcels and must be interpreted using sophisticated algorithms. A new growing market is the inspection of LCD monitors and HDTVs, which should ensure that each pixel on your screen is working flawlessly.

Life science imaging is another rapidly growing sector with tremendous business potential as well as unprecedented consumer benefits. For example, digital mammography can provide better images using less radiation in far less time than traditional film. DALSA Life Sciences has extensive experience in x-ray imaging in applications such as: Mammography, Radiography, Bone mineral densitometry, and other medical x-ray imaging such as micro computed tomography, dosimetry/photometry, and radiation treatment planning.

Click for original image (4 Megabyte!) from the UltraCamX camera system.The Image Sensor Solutions are used in advanced products for Digital Photography, (Aerial) Photogrammetry, Medical (X-Ray, Dental), Broadcast, Machine Vision, and Scientific application (incl. Space). Some impressive milestones have been the 26 megapixel CCD which has already been developed in 1993, the 111 million pixels CCD (10,560 pixels x 10,560 pixels) which has been produced for the U.S. Naval Observatory in 2006. Beijing Olympics 2008A growing business is geospatial imaging and you will certainly have been looking at images from DALSA sensors in Google's Maps, Microsoft's Virtual Earth and other global mapping services. You might even have seen images from a great deal further away as the Mars Exploration Rovers are equipped with sophisticated camera systems that have DALSA CCD image sensors onboard. And most of you will recently have been looking at images created by DALSA sensors, as most of the host broadcaster's HD cameras at the Beijing Olympics were equipped with their sensors.

Digital Cinema

The motion picture industry agrees that the future is digital. It also agrees that HD resolution (or "2K") just doesn't measure up to traditional film, even if you're only using a television to display it. That’s why film classics such as The Wizard of Oz and Goldfinger were restored at 4K resolution and an increasing number of film-originated features (such as The DaVinci Code and Spiderman2) go through a 4K digital intermediate process. DALSA, as a leader in 4K, provides the most extensive and complete line of 4K capture gear possible, from its Evolution and Origin 4K cameras and optimized lenses to 4K data recorders and accessories. These advanced 4K cameras and other sophisticated equipment, ranging from the latest ENG and EFP cameras to complete screening rooms make up the DALSA professional rental service.

Digital photography

The recent announcements of the 60.5 megapixel PhaseOne and the 56 megapixel Leaf medium format cameras have renewed the interest in larger format digital cameras and at the same time revamped the discussions on the advantages and disadvantages of the steadily growing number of megapixels in digital photography. Of course, there’s quite a bit of difference between an 8 megapixel sensor in a camera phone and a 60 megapixel sensor in a medium format camera, but the same technological problems may affect overall image quality.

Sensor performance

Typical image sensor vs. Dalsa image sensor Image sensors sense light (photons) and generate a signal (electrons) depending on the color (frequency) and brightness (luminance) of the light, and you can understand that a larger pixel means more light and more photons. As the number of pixels increases and the sensor package size decreases, the pixel dimensions will get smaller and smaller. However, smaller pixels mean fewer photons, which means fewer electrons and this will lead to a smaller output signal and with the same noise levels the signal-to-noise ratio will increase proportionally, and image qualify will suffer. DALSA has tackled these problems from two angles:

The signal - A pixel on an image sensor is made up of a microlens, a color filter, the metal wiring and the silicon substrate that collects the light. In most sensors the height of the metal wiring is around 6 micron and the effective fill factor is about half of the total pixel surface. In their latest 6 micron sensors DALSA has managed to increase the fill-factor to 95% and to reduce the wiring height to about 3 micron, half the size of the silicon width, thereby increasing the effective pixel aperture and thus the signal level while maintaining minimum color cross talk between red, green and blue pixels.

Note that Sony and Omnivision have recently announced a different approach to increase the effective pixel size for image sensors in consumer products whereby the location of the wiring and the silicon are reversed, and thus effectively increasing the width to 100% and reducing the height to zero.

The Noise - The complementary method for increasing the signal-to-noise ratio is to decrease the noise level. Noise is unwanted electrical or electromagnetic energy that degrades the quality of signals and data. DALSA has achieved this through decreasing the noise of the amplifier that converts the electrons to an output voltage. By optimizing the technology and design of this amplifier, the noise level was decreased by about 30%.

Circle of Confusion

Diffraction limited image"Circle of confusion" is a term used in relation with camera optics, yet this same term may be true for the myths about diffraction. Just Google for terms such as "diffraction limit", "circle of confusion" or “airy disk" and you'll find numerous articles on the subject, and sometimes amusing or even heated discussions in the forums.

As Jan Bosiers explains: Diffraction of light is a phenomenon that results from the obstruction of a wave front of light, and blurs the edges of optical images. The degraded sharpness is solely determined by the imaging components themselves and the optical wavelength. Thus, the lens system defines the diffraction limit and not the pixel size of the digital image sensor. The optical effect is equal for analogue and digital cameras, but with the difference that a digital camera pixelizes the image. In order to minimize the effect of the pixels and enhance the image resolution, small pixels are preferable. This also accounts near the diffraction limit.

Diffraction of light will be less observable on color image sensors using the RGB Bayer pattern. The image pixels form a matrix in which the left/right and above/below neighbor-pixels always have different color filters that filter the impinging light conform their spectral response. For the final full-color image, the color interpolation results in a reduced the visual impact of diffraction. Therefore F-stops up to F/16 and F/22 can still be used without any significant diffraction problems for sensors with 6x6 micron pixels.

Clean-room visit

Bert Wijnen (behind the camera phone) and Bas van HoutumWe were very pleased to be invited (allowed) for a visit to the DALSA clean room. We all know the importance of clean room production and we have often enough seen reports, pictures and videos about clean rooms. Only by visiting such a clean room one gets a good impression how elaborate and delicate the process is. To manage a contamination level of only 100 particles per cubic meter turns out to be a major challenge. It took us quite a long time - a costume change at the musical Cats would be quicker - to get "dressed" before we could enter the clean room. Obviously, the people who work here everyday do it much faster.

We were impressed to see that each step in the production process starts with an extensive quality check. Bas van Houtum explains that, although the wafers arrive in very high quality from the foundry, DALSA's first step in the manufacturing process is a very thorough analysis of the wafer surface to optimize the end quality and yield within the production flow. Powerful computers support the process during all phases to ensure optimal quality. Each sensor carries a unique tag to trace it during production and, if needed, even while in use in the customer's environment. No sensor leaves the clean room without an extensive stress test to simulate the extreme conditions in which some of these sensors will have to operate later on.

The future

As we could have expected, DALSA was not at liberty to reveal any information on upcoming products, nor camera manufactures planning to implement DALSA's standard or specialized image sensors. DALSA will be present at the Photokina 2008, in Cologne at September 23-28. Nevertheless, as the number of players in the advanced camera market has reduced considerably over the last years, we tried our luck and tossed the names on the table of the two players that seem to linger behind in the 50+ class, i.e. Sinar and Mamiya.

No comments though, just friendly smiles….

September 3, 2008
go to top of page