Services in the Field of Optical Sensors

Optical sensors in CMOS technology

We develop application-specific optical sensors and sensor systems. The sensors can be designed as individual sensors or as line or image sensors and feature integrated signal processing and interfaces. They are produced using CMOS technology and can be manufactured cost-effectively in high volume.

Color and multispectral sensors

We develop color and multispectral sensors for specific applications. To capture the spectral characteristics of light, we use photodiodes and optical nanostructures in the metal layers of CMOS processes. This means color and multispectral filters can be produced with no need for subsequent production steps (without post-processing).  

These highly integrated color sensors are suitable for use in gas and liquid analysis as well as in complex applications such as color control for LED lighting systems.

Our service portfolio:

  • Simulation of optical nanostructures that act as spectral filters
  • Design of photodiode arrays and image sensors
  • Production process for integrated sensors
  • Electrical and optical characterization
  • System design for applications, e.g. LED control and analysis
CMOS multispectral sensor
© Fraunhofer IIS/Stephan Junger

CMOS multispectral sensor

Polarization sensors

Unlike intensity and color, polarization is a property of light that is imperceptible to the human eye. We design, develop and characterize integrated optical sensors including polarization filters for analyzing the polarization state of light. Integrated into the chip, the filter effect is achieved using optical nanostructures (in this case, grating structures) in the metal layers of the CMOS semiconductor process. These filter structures are combined either with photodiodes (individually or in an array) for spot measurements of polarization or with the pixels of an image sensor for polarization imaging. We can adjust both the number of photodiodes as well as the pixels in order to meet customer requirements.

Polarization sensors can for instance serve as optical rotary encoders, in polarization cameras for material inspection of glass or in the automotive sector (driver assistance systems).

Our service portfolio:     

  • Simulation of optical nanostructures such as wire-grid polarizers
  • Design of photodiode arrays and image sensors
  • Production process for integrated sensors
  • Electrical and optical characterization
© Fraunhofer IIS/Stephan Junger

Optical rotary encoder

Multi-aperture image sensors

We develop multi-aperture image sensors for ultraflat high-resolution cameras in mobile devices. Modeled on insects’ compound eyes, multiple cameras take pictures of individual parts of the scene using microlenses and then stitch them together to form an overall image, simultaneously delivering 3D information. Compared to conventional camera designs, this permits a 50% reduction in installation size (height)  for the camera module.

These ultraflat cameras are ideal for applications in smartphones, in the automotive sector and for machine vision in industry 4.0.

Our service portfolio:     

  • Design and development of application-specific image sensors, e.g. multi-aperture image sensors, sensors with special pixel arrangements
  • Characterization of multi-aperture image sensors

These multi-aperture image sensors are being developed in the facetvision project.

© Fraunhofer IIS/Max Etzold

Multi-aperture image sensor for ultraflat cameras

Sensors for time-of-flight measurements of light

Time-of-flight measurements of light can be used to measure the distance to an object. Optical time-of-flight measurement detects when a pulse of light emitted from an object is reflected and sent back. This relies on single-photon avalanche diode (SPAD) arrays, in which each photon that hits a sensor causes an avalanche of electrons. This makes individual photons visible, permitting optical time-of-flight measurements.  

For each application, we develop time-of-flight (ToF) image sensors that can determine the position of an object with high precision. Time-of-flight cameras for 3D object recognition work at a high resolution and high recording speed. Light detection and ranging (lidar) technology can be used like radar to provide real-time measurements of the distance to an object and to a certain extent its velocity as well. One application of ToF cameras is in driver assistance systems in the automotive sector. Here, they can record the car’s entire surroundings in 3D, including the motion of pedestrians or moving vehicles. ToF image sensors are also used in robotics for industry 4.0 (human-machine interaction).

Our service portfolio:

  • Development of application-specific time-of-flight sensors
  • Characterization of ToF sensors
© Fraunhofer IIS

SPAD pixels

Characterization of optical sensors and image sensors

We operate several measuring stations both for our own sensors and for our customers’ sensors.

Photodiodes and optical sensors:

  • Measurement of sensitivity and linearity (A/W) in relation to wavelength (200 nm – 1100 nm)
  • Measurement of sensitivity in relation to polarization and determination of polarization contrast

All measurements can be made relative to the angle of incidence of the light and at various temperatures.

Image sensors and pixels:

Measurements can be conducted in accordance with the EMVA 1288 standard.

  • Measurement of sensitivity (quantum efficiency) and linearity in relation to wavelength  (200 nm – 1100 nm) in monochrome cameras, color cameras and multispectral cameras
  • Measurement of sensitivity in relation to polarization and determination of polarization contrast in polarization image sensors and cameras
  • Illumination and characterization of individual pixels: Measurement of the above variables and of crosstalk in relation to frequency

Pixel characterization can be performed for various angles of incidence.

© Fraunhofer IIS/Kurt Fuchs

Illumination of an optical sensor

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Brochure

Nanostructured Colour and Polarization Sensors in CMOS-Technology

 

Flyer

Plasmonic Colour Sensors for LED Monitoring and Colorimetry

 

Brochure

CMOS Image Sensors and Camera Systems