It's an E45, about a year old, uncooled. About every 30 seconds, it clicks and seems to close an internal shutter for a couple of seconds, which I assume is some sort of auto-cal of the sensor array.
It's pretty slick, except for the USB interface which is bizarre. It's a network device, not memory like other cameras, and you have to install their strange software to talk to it.
We can focus so close that we can image the hot-spot temp on an 0603 resistor! Imaging an operating pcb can lead to all sorts of revelations.
We looked at the Fluke, but nobody at Fluke seemed to understand it. Not a good sign.
The internal shutter is for NUC (Non-Uniform Correction) -- focal plane array sensors in general (even visible light) have gain and offset differences from one pixel to the next. Part of it is periodic with the internal structure of the chip or with polish marks. The rest is just purely random. Visible light sensors can be selected to eliminate this to some extent (pro video cameras have nonuniformity correction, but the camera manufacturers won't admit it). IR detectors can't, and the amount of nonuniformity in the uncooled detectors can be astonishing; as of five years ago it could be 100x as much as your intended signal.
So every once in a while the shutter comes down, the internal logic recalibrates the NUC, and the camera continues on.
There are only a few companies that actually manufacture imagers (FLIR Sweden is one). So many companies that "make" IR imagers are just plopping an OEM module made by someone else into their case.
--
Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
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Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
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Not if the surface that got anodized was "shiny", as it were. A good black body source is aluminum (thick) as it conducts heat fairly evenly, but the ideal surface is a very matte finish, or even concentric rings cut into the face and then painted or anodized after a grit blast session.
Shiny is bad, which is why water is bad, despite it also being a very good, even conductor of heat. The shiny surface reflects the IR back into the medium, hence reduced emissivity.
You can find a fairly decent emissivity chart here, as well as a very good primer on the subject:
Color isn't the issue. The surface of water is VERY reflective, so any IR the medium generates get reflect BACK into the medium. This is why water has such a poor emissivity.
A matte finish Aluminum block/box filled with a known temp water (circulating) would likely be only a couple tenths of a degree off the water temp, and would allow the IR gun to be calibrated very well.
K. Irani invented the "resistor bolometer" back in 1960.
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They have imagers, but likely get their sensors from an OEM house, as does FLIR most likely. Chip fabs ain't cheap endeavors.
The best thing about a good IR device maker is the electronics behind the instrument.
FLIR buys their calibration sources from these guys.
These guys are the top dogs in non-contact temperature measurement.
We made some that are still in use at the shuttle launch pads that have the longest IR focal length made for a calibrated instrument.
The observation shacks are 1000' from the pad, and the instruments observe a ten foot spot, and detect a 200° C change within a one foot spot in that circle (1° FOV). The area observed is known as "the protected area". It is near the blast chutes on the pad.
When IR imagery was in its infancy, their device was $90,000, and was 4 frames per second, and we had early 386s back then, and there was not even a way to get the images off onto VHS. At least it was 16 colors.:-] We also had one that looked through a microscope.
Now, they are likely 16 bit color, and the image data can be manipulated post capture. These guys are pretty good.
I used to build a 2.5 foot by 4 inch, gold mirrored, rifle stock and scoped analog unit that power companies used to point at insulators and transformers to get status without having to climb poles or towers.
Now, they just point an imager at them. And a fairly cheap one at that.
How can the focal length change the emmisivity or the effective temperature? If the surface is a mirror in the thermal IR, all you ever image is a reflection of *something*, but you don't measure the temperature of the mirror itself. Shiny copper has an emissivity of about 0.05, so 95% of whatever the IR meter is seeing is the reflection of something else.
Having tested a number of ways to increase the emissivity of shiny metallic surfaces, I know that black whiteboard marker brings the emissivity almost all the way up to 1.0. And it's easy to wipe off after you're done. Is 1.0 within your definition of "if at all"?
Do the math. Delta-t across scotch tape, working against air, is usually tiny.
Gosh, didn't somebody recently say that
'Surface quality is the most determinant factor, not "color"'?
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