Short-Wavelength InfraRed
Image Sensor Technology SenSWIR™
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Overview
SenSWIR is a wide-band and high-sensitivity SWIR image sensor technology implemented by the combination of compound semiconductor InGaAs photodiodes and Silicon readout circuits through Cu-Cu bonding.
SWIR (Short Wavelength Infra-Red) light penetrates and is absorbed by different substances than visible light, so its attributes can be applied in a variety of different situations.
*) SenSWIR and its logo are registered trademarks or trademarks of Sony Group Corporation or its affiliates.
Technical Features
Higher pixel count, smaller systems
Creating SWIR sensors with smaller pixels than in current industrial CMOS image sensors has been challenging with conventional bump bonding, because a certain bump pitch must be maintained to bond the indium-gallium-arsenide (InGaAs) photodiode layer to the silicon readout circuit layer. With SenSWIR technology, Cu-Cu connection*1 enables a finer pixel pitch and smaller pixels. As a result, smaller high-resolution cameras can be developed, which can support higher inspection precision.
*1)A technique that provides electrical conduction by bonding copper pads, as the pixel chip (top) and logic chip (bottom) are stacked. Advantages over the previous through-silicon via approach (which electrically connects top and bottom chips at the edge of the pixel area) include smaller systems and improved performance, which affords greater freedom in design and promises higher productivity.
Broad imaging that extends to the visible spectrum
The top indium-phosphorus (InP*2) layer inevitably absorbs some visible light, but applying Sony's SWIR sensor technology makes this layer thinner, so that more light reaches the underlying InGaAs layer. The sensors have high quantum efficiency even in visible wavelengths. This enables broad imaging of wavelengths from 0.4 μm to 1.7 μm. A single camera equipped with the sensor can now cover both visible light and the SWIR spectrum, which previously required separate cameras. This results in lower system costs. Image processing is also less intensive, which accelerates inspection. These advances promise to expand the scope of inspection significantly.
*2) Substrate that forms the base of the InGaAs layer.
What's SWIR?
Generally, light with a wavelength of 400 nm to 780 nm is referred to as visible light, and light with a wavelength of 780 nm to 106 nm as infrared light. The wavelength band of SWIR is from 900 nm to 2,500 nm, which is the region of infrared light closest to visible light. Image sensors equipped with SenSWIR technology are capable of broad imaging over the range of 400 nm - 1,700 nm, including visible light as well as SWIR light.
Applications
Sorting fruits and vegetables
Water becomes black in an image taken with a SWIR image sensor set at the wavelength of 1,450 nm because water absorbs the light at this wavelength. Since this makes it possible to detect moisture contained in objects, it can be used for applications such as fruit and vegetable sorting.
Example of sorting fruits by detecting dents or scratches
SWIR imaging makes the moisture concentrating in dents on the apples visible.
Related sectors
Container content inspections
In food manufacturing processes, performing final content inspections is difficult if the food packages are opaque. In some cases contents are pinched in the sealing part when the package is closed, which are also hard to detect.
Even if packages appear opaque in the visible range, it may be possible for light in SWIR wavelengths to penetrate them and allow their contents to be observed. By using this property, the inner areas of packages can be checked non-destructively and pinching errors can also be detected.
Example of detecting content conditions by observation that penetrates through a plastic container
Explanation of photo: SWIR imaging makes it possible to check the content of opaque containers.
Related sectors
Contaminant detection
In food product manufacturing, inspections to check for the introduction of contaminants are essential. However, if contaminants mixed in with a product are similar in color to the product itself, it may be difficult to identify them using only visible light.
Utilizing the absorption and reflection properties of SWIR-band light makes it possible to perceive differences between substances that are difficult to see with visible light alone. With these attributes, SWIR image sensors can be used for contaminant detection and similar applications.
Example of detecting contaminants in food
SWIR imaging makes it possible to distinguish between a food product (black beans) and black-colored contaminants.
Example of detecting walnut shells by processing images taken at multiple SWIR wavelengths
SWIR imaging enables easy identification of walnut shells that are difficult to see with the naked eye.
The image on the right is a pseudo color image taken at three SWIR wavelengths. Such image processing makes it easier to distinguish between walnut shells and the walnuts themselves.
Related sectors
Food/Medicine/Cosmetic Manufacturing
Related Links
Working to Realize Optimal Multi-Spectral Cameras for Contaminant Detection
Sorting materials
There are many different types of plastics, and since each type requires a suitable method of recycling, the first step at recycling sites is to sort them apart from each other.
Since plastics are transparent in the visible range, the properties of each type of material cannot be identified, but by examining them with light in SWIR wavelengths (particularly multiple wavelengths), it will be possible to determine their properties and sort them accordingly.
Related sectors
Positioning in Semiconductor Manufacturing
Due to the miniaturization of semiconductor devices in recent years, high accuracy has become required even in layering processes for silicon wafers. In order to raise their accuracy, it is important to accurately align marks used for wafer positioning.
Light in SWIR wavelength bands has the property of penetrating the silicon layers of wafers, so applying SWIR image sensors can make it possible to clearly confirm positioning marks. High definition SWIR image sensors from Sony are also anticipated to be used to improve edge detection accuracy.
Example of imaging by penetrating silicon wafers
The photograph on the right was taken in an SWIR environment, so the resolution chart behind the silicon wafer is visible. This was taken using an IMX990 sensor at a high resolution of approximately 1.34 megapixels, so even small marks can be detected with high precision. In addition, using an IMX992 sensor, which has a resolution of approximately 5.32 megapixels, enables even higher-definition inspection and measurement applications.
Related sectors
Temperature monitoring
Image sensors can perceive differences in the temperatures of substances as differences in luminance. Among them, substances at temperatures of roughly 250ºC or higher emit light in the SWIR band, so SWIR image sensors can be used in applications for monitoring high temperatures of 250ºC or higher. This characteristic is expected to be applied in the steel industry.
Example of monitoring the temperature at the tips of soldering irons
In the SWIR image, it is possible to confirm not only that the tips of the soldering irons have become hot, but also to identify their differences in temperature.
Related sectors
Firefighting
In firefighting, smoke may compromise the firefighters’ field of vision. SWIR image sensors, which are less affected by light scattering, can be used to ascertain the situation at the sites of fires and assist firefighting efforts, as they can capture images while suppressing the impact of smoke.
SWIR light is also emitted by flames, which can be clearly captured by SWIR image sensors. This makes SWIR image sensors particularly useful for identifying the source location of forest fires and other wildfires.
Related Contents: Utilization of the SWIR Image Sensor in Firefighting
Remote monitoring
In remote monitoring, airborne micro-particles can cause far-off targets to become blurred, making it difficult to accurately capture them with cameras. Comparatively, SWIR-band light, which has longer wavelengths than visible light, has the attribute of being affected to a lesser degree by airborne micro-particles than visible light, making it easier for far-off targets to be captured clearly. SWIR image sensors can therefore be utilized in applications for remote monitoring.
Related sectors
Observation of agricultural lands
At agricultural sites, initiatives to observe agricultural lands from the sky with cameras are currently proceeding. Now that it has become possible to understand the growth conditions of crops, limited additional fertilizing and yield forecasts based on data can also be implemented.
However, it is not a simple task to make judgments on growth conditions using only color data. If SWIR image sensors are used, moisture content can be visualized so growth conditions and distribution according to moisture volume can also be expressed visually, and more accurate judgments can be made.
Related sectors
Download
Image Sensors with SenSWIR Technology
Introducing the details of the technology used in this SWIR image sensors
The SWIR Camera Photography Process and How Multispectral Images are Created
(The Food Inspection Edition)
This document explains some key points and photography tips along with an example use case for SWIR camera evaluation.
IMX900/IMX991/IMX992/IMX993 Product Overview
This document summarizes the product overview, features, and specifications.
Related Products & Solutions
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Image sensor
SWIR Image Sensor
Click here for the overview page on our SWIR image sensors that use SenSWIR short-wavelength infrared image sensor technology.
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Image sensor
IMX990/IMX991 SWIR image sensors
Click here for product information on SXGA/VGA SWIR image sensors.
IMX990 (1/2" 1.34MP), IMX991 (1/4" 0.34MP) -
Image sensor
IMX992/IMX993 SWIR image sensors
Click here for product information on even higher-resolution SWIR image sensors.
IMX992 (1/1.4" 5.32MP), IMX993 (1/1.8" 3.21MP)
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