SWIR IMAGING g


using quantum dots, from Emberion, a firm based in Finland and the UK. Te first product samples of the sensor,


which offers VGA resolution, 20µm pixel pitch, 100fps frame rate, and a spectral range from 400nm to 2,000nm, will be available in June 2020. ‘Tis wide spectral range is the key


advantage that our sensor provides over standard InGaAs sensors, which tend to go between 900nm to 1,700nm,’ said Jyri Hämäläinen, director of sales and marketing at Emberion. ‘Beyond 1,700nm is usually called “extended InGaAs”, and it is here that InGaAs technology becomes very expensive. In comparison our sensor is much more affordable while being able to detect these wavelengths.’


‘Graphene-enhanced photodiodes provide superior responsivity and very low noise’


Emberion is targeting both


monochromatic machine vision and hyperspectral camera manufacturers with the new sensor – particularly those with customers looking to image over a broader spectral range than they can achieve at the moment. ‘We think this sensor will also be interesting to those currently working in the visible wavelength range that are looking to experiment with other wavelengths,’ added Hämäläinen. While the new sensor will be available as


a standalone product, Emberion is looking to offer the technology as a full camera core that includes all the necessary electronics and connections, in order to provide camera


manufacturers and integrators a faster and easier way to integrate the technology into their products. What sets this new device apart from the other emerging quantum dot-based imaging technologies is that Emberion has used graphene to enhance the characteristics of the photodiodes, which significantly increases their sensitivity. ‘Graphene- enhanced photodiodes provide superior responsivity and very low noise,’ said Hämäläinen. As a partner of the Graphene Flagship


programme, a €1bn EU research initiative that aims to transfer graphene from the lab to the market, Emberion has received funding to develop this technology. Hämäläinen remarked that graphene is a new material in imaging, and that he is not currently aware of any other commercial activities that feature graphene being used in machine vision sensors. Depending on the customer feedback


Emberion receives following the release of its technology, the firm may choose to develop its sensor towards higher resolution. ‘Megapixel resolution might be an option, but this will depend on the customer demand,’ Hämäläinen said. ‘We will also be looking at increasing the speed and even further widening the spectral range if this is what is needed from end- users.’ With the sensor’s ability to detect


beyond 1,700nm, it could be applicable to plastic sorting applications, which have spectral peaks in this region. In addition, the hydrocarbons in certain foods also have spectral peaks here, meaning the sensor could also have applications in the agricultural industry. ‘While these applications could use extended InGaAs


A new take on shortwave infrared LEDs


In a three-year research project conducted with the French Institute of Optics, machine vision lighting firm Effilux, also from France, has developed an LED SWIR source that it says addresses the drawbacks of current SWIR LEDs on the market.


Arnaud Mestivier, sales manager for Effilux, explained that despite the advantages of LEDs – long lifetime, robust, and less heat dissipation – those that provide SWIR illumination deliver less power and are more expensive than standard LEDs.


While visible LEDs deliver around 1W of optical power, SWIR LEDs only offer approximately 20mW to 50mW. The cheapest solution for SWIR illumination capable of delivering the most optical power was therefore previously halogen bulbs, according to Mestivier, which deliver 100 times more optical power than SWIR LEDs. Now, however, as a result of


the research project, Effilux and the French Institute of Optics have developed the SWIR High Optical Power LED source. According to Mestivier,


12 IMAGING AND MACHINE VISION EUROPE DECEMBER 2019/JANUARY 2020


the technology retains all the advantages of LEDs compared to halogen bulbs, while also offering considerable improvements in power, as well as the flexibility to create both highly focused SWIR beams and large area uniform SWIR illumination. The new source uses low-


cost LEDs emitting at 940nm to pump a crystal that re- emits at 1,550nm, which – for a similar price – produces 10 times more light than a 1,550nm SWIR LED. In addition, Mestivier said that one chip of


the technology is able to emit a luminous flux comparable to a 50W halogen source. As a result, many expensive SWIR LEDs can now be replaced by a single SWIR High Optical Power chip, resulting in lower costs for system builders using SWIR illumination. The LED chip offers


approximately 50,000 hours of operation, high stability and reliability, quick pulse operation, compact size, no excessive warm up, and low power consumption. It is also fully eye-safe.


@imveurope | www.imveurope.com


Test images of cookies acquired with a visual sensor (left) and with Imec’s quantum dot- based SWIR sensor at 1,450 nm (right). The bottom cookie had a drop of water applied to its surface, which can be only distinguished under SWIR light.


technology, the large cost associated with this often leads to end-users finding alternative solutions that work around this,’ commented Hämäläinen. ‘Our sensor could therefore enable these end-users to address these applications without needing a work- around. We have seen that there is definitely interest here.’ As an additional project, over the next


few years Emberion will also be working on developing a broadband imaging sensor – covering everything from visible light to the longwave infrared. According to Hämäläinen, initial research prototypes for this technology already exist. ‘We believe this will bring a totally different dimension to imaging, including new opportunities in machine vision,’ he remarked. ‘We are looking to hear from companies who would be interested in this technology so they can tell us what they need, and then we can steer our development towards achieving the required specifications.’ O


Imec


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