iRAY T3S Thermal Camera Performance Analysis

Introduction 2

Piséo’s opinion of the iRay T3S camera 3

Objective of the report 4

About Piséo 5

Glossary 8

Executive Summary 9

T3S camera functionalities and use 34

• Camera presentation
• Microbolometric sensors
• Packing and presentation
• Technical characteristics of the camera
• Technical characteristics of the microbolometric sensor
• Starting operation
• Handling and functionalities
• Bolometric sensor technical characteristics
• Physical connections and interfaces
• Handling and functionalities – smartphone plug-in
• Xtherm interface
• Color mapping
• Temperature measurement functions
• Temperature measurement settings
• Imaging temperature ranges
• Shutter correction error with temperature range activation – description
• Shutter correction error with temperature range activation – details of error
• Physical connection

Image production flow and analysis 50

• Image production – simplified pipeline
• Hardware configuration for the image production
• Main hardware devices and functions
• Image retrieval
• Raw image and corrected image

Image sensor characterization methodology 56

• Image sensor characterization
• Image production
• Blackbody setup
• MTF measurement – description
• MTF Measurement – slanted edge method description
• FPA temperature measurement
• Responsivity and NETD
• Linear scene dynamic
• Bad pixel detection and operability
• Non-uniformity correction and RFPN
• Thermographic function

T3S imaging performance characterization 68

• Introduction
• Responsivity, NETD, scene dynamic 20°C – 40°C
• Operability, +20°C, +40°C
• Responsivity, NETD, scene dynamic -20°C to +100°C
• Operability, +20°C, +100°C
• Dependence on ambient temperature
• FPA temperature stability
• Flat field correction
• FFC comparison with 2-point NUC
• Residual fixed pattern noise
• Thermographic response
• Shutter activation
• Image quality in extreme temperature cases

T3S Temperature sensing analysis 82

• Characterization methodology
• Performance and accuracy
• Influence of the emissivity on the temperature measurement
• Physics of emissivity
• Application to skin temperature measurement
• Synthesis of the temperature measurement performance

Optical analysis 89

• Cross sectional analysis
• Optical performance
• Control of the focal distance
• Optical analysis conclusion

Image processing and tone mapping analysis 94

• Methodology
• Image processing
• NUC correction
• Sharpening
• Histogram equalization
• Gamma correction
• Image processing flow chart
• Synthesis

Conclusions and opinion 109

• Synthesis of imaging performance
• Conclusion
• PISEO’s opinion of the iRay T3S camera

PISEO 114

Contact 121

FIRST TIME EVER PERFORMANCE ANALYSIS REPORT

Thanks to multiple drivers, a.o. the need for large number of temperature measurements of people due to COVID, the market for infra-red thermal imaging cameras and modules is expanding at a rapid pace. Therefore, there is a need for users, integrators, and sensor manufacturers to be able to discriminate between marketed products based on accurate and independent assessment of their performance and features.

As there is hardly any independent infra-red camera or module performance data available, purchasers of such systems are left with datasheet values that can be right or not, or provide only limited information.

Therefore, this technical report, which, to Piséo’s knowledge, is a first time ever providing independent, accurate and detailed performance data. It will be followed soon by other reports which will include analyses of Flir, Seek Thermal, Guide, HIK Vision… cameras and modules.

Carried out by a team of experienced optical and system engineers, this technical report relies on robust and comprehensive test protocols and thorough analyses of the test results. The outcome of this process is a set of typical performance indicators, such as responsivity, NETD, scene dynamic, operability… and functionalities assessment. Together, they made it possible for Piséo to develop its own opinion of the iRay T3S Camera: it has shown to be a good value for money product but with some improvements necessary.

We have greatly appreciated:

• The good correspondence of the datasheet values with our own measurements
• The good image quality provided thanks to a very good bolometric sensor and a performant 3-step tone mapping process
• Xtherm’s user-friendly interface

We have less appreciated:

• The manual focus which requires the user to often search for the focal point
• The need to de-assemble the lens from the camera for packing purpose, which allows for dust to be deposited on the sensor
• The risk of making large temperature measurement errors if the user has no background in thermal measurement principles

We did not explore:

• The thermal measurement algorithm

TEST PROTOCOLS AND FINDINGS

As a starting point, Piséo looked into the technical characteristics of the camera and analyzed the functions offered by extensive use testing. Then, thanks to System Plus Consulting’s (www.systemplus.fr) reverse engineering analysis of the T3S camera, which we have access to, Piséo has been able to accurately determine the microbolometer characteristics and camera construction. This first was essential to carry out the performance tests. Indeed, for the latter, Piséo developed its own test protocols and software interfaces which, through proper connection with and use of the camera, enabled them to gather data at sensor pixel level at various temperatures.

By using their own stabilized HGH black body, climate chamber and specific protocols and software Piséo’s team was able to perform numerous tests at various temperatures ranging from -20°C (-4°F) to 100°C (212°F). By doing so they have been able to compare the rated data displayed in the iRay datasheet with their own test results. Thus, the report presents a detailed overview of our characterization process and a collection of performance indicators of the embedded sensor expressed in values and graphs. Below are a few examples of graphs of the report that disclose some of our findings of the microbolometer sensor performance.

Through its test protocols Piséo also assessed the temperature measurement function which is a particularly sensitive topic when attempting to measure with this type of device, particularly in this time of the Covid-19 epidemic. Results are clearly dependent on the emissivity of the object measured. Our analysis shows that non-trivial understanding of thermal management principles is required to measure temperatures accurately with such a device and that precautions need to be taken with the temperature values displayed by the T3S camera on an attached terminal.

Last but not least Piséo’s team made a full analysis of the image processing and tone mapping. The report presents the different steps and algorithms used to produce the final image and an assessment of its quality.

Altogether, there is much in-depth technical information available in the report which will allow you to understand in detail how the T3S camera from iRay performs, from the sensor characteristics to the image production, as well as the user experience.

Report content:

• Piséo’s opinion of the iRay T3S camera
• Functionalities and use analysis
• Image production flow analysis
• Imaging characterization protocols and results at various temperatures:
  • Responsivity
  • NETD
  • Scene dynamic
  • Operability
  • Dependance on ambient temperature
  • FPA temperature stability
  • Flat field correction
  • FFC comparison with 2-point NUC
  • Residual fixed pattern noise
  • Thermographic response
  • Shutter activation
  • Image quality in extreme temperature cases
• Temperature sensing analysis
• Optical analysis
• Image processing and tone mapping analysis

• Responsivity
• NETD
• Scene dynamic
• Operability
• Dependance on ambient temperature
• FPA temperature stability
• Flat field correction
• FFC comparison with 2-point NUC
• Residual fixed pattern noise
• Thermographic response
• Shutter activation
• Image quality in extreme temperature cases