Dec 2015 - Test&Measurement
When Extreme Uniformity isn’t Considered Boring…
In order to increase productivity, more and more infrared camera manufacturers have developed parallel calibration processes, where a set of sensors are facing a reference source, consisting of a large area blackbody. Consequently, demanding constraints are reported on the specification of the reference source: the thermal radiation of each point of the emissive surface of the large area blackbody has to be accurately monitored.
As an example, let’s consider the mass production of IR sensors for smartphones and human body temperature sensors: typical configuration is up to 9 IR sensors simultaneously calibrated using a 180 x 180 mm² blackbody. The maximum required difference of calibration from one sensor to another is 0.1°C at 42°C. This specification is directly transferred to the non-uniformity specification for the infrared reference source.
Uniformity thermal map of a 180x180 mm² blackbody
(dark blue=48.927°C; hot red = 49.311°C)
Measuring the uniformity of IR reference sources such as blackbodies is a challenging operation, as demonstrated by Catherine Barrat at the SPIE Security+Defence conference in September 2015. The full paper presented at this conference can be downloaded in the document section of HGH's website. As the residual non uniformity level of thermal imagers is higher than the expected non uniformity on blackbodies, the use of thermal imagers for uniformity measurement turns out to be absolutely inefficient.
Recognizing this inefficiency, HGH Infrared Systems has proactively developed a testing bench for accurate calibration and measurement of uniformity of infrared sources based on a low noise radiometer mounted on translation stages. This bench delivers a reliable thermal map of any blackbody and performs an accurate calibration through a comparison method.
Please check out the video below and discover how the calibration and uniformity test bench operates.
IR sensor characterization certified by metrological standards
At OPTRO 2016 symposium, on February 3rd at 9am, HGH will give a lecture to further explain the specific challenges to IR camera calibration. We will unveil the performance of the calibration test bench, shown in the above video, characterizing, with the highest accuracy, the key element of IR sensor calibration process: the infrared reference source.
Come and visit us at booth #4 for deeper insight on opto-electronics metrological devices.
IRFPA testing with ultra-low noise and high quality optical stimuli
BIRD 210TM is a universal electro-optic test bench enabling the exhaustive and accurate characterization of any type of InfraRed Focal Plane Array (IRFPA).
Based on a state-of-the-art electronic cabinet, feeding the detection array under test with ultra-low noise signals, and optical stimuli generator bench, with motorized broadband and monochromatic reference sources, from 0.4 µm to 18 µm spectral range, BIRD provides an accurate automatic report on:
- Noise tests: fixed pattern noise, temporal noise, NETD responsivity, detectivity, 3D-noise, 2D-detectivity,
- Dynamic range, linearity,
- Non-uniformity correction,
- Bad pixel localisation,
- Spectral response,
- Crosstalk, MTF.
New BIAS Voltage Unit, with up to 20 channels
The new BIAS Voltage Unit can configure up to 20 channels, with a +/- 12V signal and a ultra-low noise current up to 500 mA, with real time display of the voltages and currents and a unique current limitation function. The new ADC16 80 Analog-to-Digital converter can handle 80 Mpixels/s rate over up to 16 channel, with a 16 bit dynamic range, allowing the test of IRFPA of up to 4Kx4K! In addition, the user-friendly BIRD software enables easy generation of clock signal, pixel remapping, acquisition and processing of detector video signal, with a unique noise and responsivity optimisation as a function of the bias voltage values.
Temporal Noise Test