Keysight Technologies – which recently branched out from underneath the Agilent Technologies umbrella – has come out with the U5855A TrueIR thermal imager. It actually came out a couple of months ago, but I only first learned about it earlier today in a supplier’s email newsletter.
What’s interesting about the Keysight TrueIR thermal imager is that it is built with a 160 x 120 pixel thermal detector, but delivers an “effective resolution” of 320 x 240 pixels.
“Fine Resolution” Technology
The TrueIR thermal imager achieves an effective resolution of 320 x 240 pixels by capturing multiple lower resolution image frames and interpolating them together.
Each image frame is going to contain slightly different information, thanks to vibrations and motion introduced by the user’s hand. Under the hood, the U5855A performs calculations on each captured image frame and makes alignment adjustments to produce one Fine Resolution image.
This is all done in an automatic three step process:
- Multi-frame acquisition
What is important to note is that, in Keysight’s own words, the new pixels are predictive values instead of measured values.
During the reconstruction process, new sub-pixels of the interpolated higher resolution image are predicted using data from adjacent pixels captured through the low resolution detector. The thermal imager then enhances and sharpens the resultant thermal image using many modeling and image processing techniques, such as an averaging algorithm, noise reduction, and an edge enhancement algorithm.
Keysight says that the interpolation process is so fast that the high resolution interpolated images are created in realtime.
If all this doesn’t make sense to you, this is how I understand the process: The 160 x 120 pixel detector captures a total of 19,200 temperature measurements and data points for each captured image frame. Each data point is then split into 4 sub-pixel data points as the image is up-scaled to a higher resolution. You now have a 320 x 240 pixel image with 76,800 data points. Multiple frames, with slightly shifted images due to hand vibrations, contain slightly different information that can be combined to fill on some of the new data points. Interpolated temperature measurements for each sub-pixel that still needs to be filled in are based on surrounding data points to complete the picture.
Features and Specifications
- Even weight distribution allows it to stand on its own
- Free TrueIR analysis and reporting software
- 3.5″ color LCD display
- Hand strap
- Video output port
- DC power input jack
- Lens shutter
- Manual focus adjustment ring
- Laser pointer
- Visible image camera (3.1 MP)
- -20 to 350°C temperature measurement range (-4 to 662°F)
- 0.07°C temperature sensitivity (0.1°C at the wider temperature range)
- ±2°C or ±2% accuracy (±4°C or ±4% at 10 to 50 cm)
- 160 x 120 thermal detector resolution
- 320 x 240 simulated detector resolution
- 8 to 14 µm spectral range
- 9 Hz frame rate
- 28° x 21° field of view
- Focus distance of 10 cm to infinity
- 0.1 to 1.0 emissivity adjustment
- 4x digital zoom
- Rainbow, iris, hot iron, gray, inverted gray color palettes
- IR image, visible image, PIP, blended imaging modes
- Center spot, 3x moveable spots, max/min tracking/ delta temperature, 3x movable boxes (min/max/avg) measurement modes
- High and low temperature alarms
- JPG image format
- SDHC card compatibility, class 4 and up, 32 GB max
- Logging mode saves IR, visible, or fusion images at defined interval of 7 to 3600 seconds
- 1/4-20 tripod mount
More Info(via Keysight)
Despite that the Keysight U5855A is built with a low resolution thermal detector, it uses a clever interpolation method to output a higher resolution image.
If comparing the Keysight TrueIR thermal imager to Flir’s Ex-series of thermal imaging cameras, the Keysight U5855A is more expensive than Flir’s $2500 E6 and a couple of hundred dollars less expensive than their $4000 E8. Then, again, the E4 can be firmware modified to unlock 320 x 240 px imaging resolution.
It seems to me that the Keysight has a less expensive sensor, but a lot of expensive electronics and computing power in order to handle necessary image processing and enhancement.
Although I have only seen Keysight’s marketing images of the U5855A’s output, their blended imaging mode doesn’t seem to be as impressive as Flir’s MSX contrast enhancement technology.
To be fair, comparing Keysight’s U5855a to Flir’s Ex series isn’t an even comparison. Going by features and capabilities, it would be a better match to Flir’s Exx series of thermal imaging cameras. The Flir E40, with its 160 x 120 px sensor, is priced at $4000 and as low as $3500, while the E60 with its 320 x 240 px sensor is priced at $8000. Fluke’s 320 x 240 px thermal imaging camera is priced at $8500.
The Keysight thermal imager doesn’t have built-in video capturing, or at least it doesn’t seem to going by their datasheet, nor does it have built-in WiFi or Bluetooth connectivity as Flir’s Exx series of thermal imaging cameras.
From a features, capabilities, and comparative standpoint, the Keysight U85855A TrueIR thermal imager seems to be reasonably priced. It looks to be an interesting and more economical tool for capturing higher resolution 320 x 240 px imagery with only a 160 x 120 px sensor.
I would be happier if the thermal imager shifted its detector plane, or something to that effect, to capture a 320 x 240 px array of true thermal measurements, rather than predicted and interpolated measurements for 3 out of 4 pixels. Keysight seems convinced as to the accuracy and reliability of their interpolated image and data output, and that should be good enough for most users.