Hello my name is Schuyler Smith and I do technical sales and support here at Apogee Instruments.
Today we're going to talk about choosing the right infrared radiometer for you.
Going through all the options of infrared radiometers, that Apogee Instruments has to offer.
We're going to cover all the field-of-view options.
We're going to cover the difference between the SI-100, SI-400, and SIF series,
and then we're going to go through a demonstration of using our field-of-view calculators
that we have available as an app and on the spreadsheet.
First thing, the SI-100 and SIF-100 series are both analog.
That means that they both require two channels in order to read them:
a differential channel to read the millivolt output from the thermopile
and then a single-ended channel in order to read the sensor body temperature,
which is the thermistor and so those thermistors are usually measured with half-bridge measurements.
The difference between the SI-100 and SIF-100 is that the SIF-100 is a fast-response,
has a 0.2 second response time, whereas, the SI-100 has a 0.6 second response.
Then you can see how that affects the signal size,
it being a much smaller signal between 5 and 15 micro volts per degree C on the SIF series,
whereas, the SI-100 is between 20 and 60 micro volts per degree C.
The SI-100 is ideal for static stations on traditional dataloggers.
The SIF-100 series is ideal if you're on a moving platform of some sort
doing measurements connected to data loggers that have that high resolution that can read that small signal.
The SI-400 series is all completely digital using the SDI-12 protocol.
That's ideal for your static stations that require multiple sensors
with a logger that can read that digital SDI-12.
Then in each one of those, we have the different field-of-view options
for the SI-100 and SI-400 series we have 4 field-of-view options.
From our narrowest 14 degree half angle field-of-view up to our horizontal field-of-view,
and then we report that in half angles.
If you want more information, you can click there on that website.
Unfortunately due to the small signal size, we only have three of those field-of-view options available.
We've put together this table to kind of explain a little bit better,
but for the largest field of view the 22 degree field-of-view we have the SI-111, SI-411, SIF-111, and MI-210.
The MI referring to the infrared radiometer connected to the hand-held meter that gives you that temperature.
You can look there to find your corresponding field-of-view for which model it corresponds with.
This is a great illustration showing that same concept.
The SI-111 is equal to th e 22 degree field-of-view.
You can see in this particular application where you're doing crop canopy that the SI-111
may not be ideal because it's seeing much more than just a crop.
It's seeing the trees and the mountains behind it, whereas,
the horizontal is seeing the most amount of the crop and just the crop without anything behind it.
We'll go through this next on the field-of-view calculator demonstration.
The field-of-view calculator is available as an app.
Just search for Apogee Instruments in your app store and you'll be able to find that
and a few other things we have to offer.
Then it's also available on our website and there's the link right there you can click on that,
and we'll just go to the website right now and go through that.
We'll just come here to apogeeinstruments.com.
Here we are on the webpage, on the homepage.
We'll come over here to support.
We will click there and then on the far side over here is infrared radiometers.
We'll click here.
Now, there is a lot of information on this page, a lot of the frequently asked questions.
If you have questions yourself, if this is going to fit for your application,
I would come look through here, and then a lot of helpful articles and links on trying to get that to work for you.
First one there being field-of-view explained,
I mentioned that on an earlier slide,
but that is the link that you want to look through if you want to get more information on that.
We're going to click on the second one here, field-of-view and canopy fraction calculators.
We just open this up here and it's going to say viewing angle and viewing height.
Let's just take for an example, let's say we wanted to do a 10 meter by 10 meter plot
and we want to measure the crop canopy inside this 10 meter by 10 meter plot.
We want to maximize our field-of-view to get as much of that in there as we can.
Let's start with the SI-111, which is equivalent to that 22 degree field-of-view
and let's just say that our viewing angle is 65 and our viewing height is 1.5 meters above the canopy.
If we calculate, it gives over here and says our field of view is seeing 122.8 meters squared, which is good information
It tells us the total surface area it is seeing but we don't really know how that's allocated.
To get those details we need to look at the excel sheet.
That's right here, this link here excel sheet program to calculate target area.
Download that and then open it up.
I've done that already so here's that excel sheet what it looks like and I've pre entered in these values.
I've chosen the SI-111, which is equivalent to 22 degree field-of-view,
65 degrees is our angle from the surface, and then 1.5 meters above the crop.
That gives us that same 122.82. If we scroll down, then we'll see those details.
First off, again we're trying to look at a 10 meter by 10 meter plot as our example.
We want to know what our length is from A to D (what our field-of-view is seeing).
If we come down here, we see right here it says 2 7.2.
That's way too long. We need to cut that down to 10.
Let's come back up and let's adjust the numbers.
Let's adjust this to 63 and be 1 meter above the crop.
We've significantly lowered this from 122 to 24.2; let's see how that allocates.
Our A to D is right here, 10.56. That's pretty close to our 10 meters.
Then our C to F or B would be our widest part.
We come down here. It's 1.46 so we need to double that so we have the full width, and that would be 3 meters.
Essentially we're at 3 meters wide and just over 10 meters long if we were to use the SI-111 in that application.
Let's look at what it would look like with the horizontal.
If we come over here and do the SI-1H1, let's go back to our original numbers of doing 65 and 1.5
(that's 65 degrees with our height being 1.5 meters above the crop canopy).
Then if we come down here, we can get our details.
We want to know first what is our length that we're looking at, and so we need to know G2 to G1.
That's equal to V right here and it says it's 5.14.
It is less than our 10 meters so that's good.
We could possibly maximize that some more, but that's less.
Then let's figure out our widest part or G2 to F times 2 is equivalent right here to 8.05.
That's not maximized either; that's less than our 10 meters.
We can come back up here and adjust them.
Let's actually just adjust it to 2.0 meters above the crop, leaving the angle the same.
We've almost doubled our surface area from 27 to 48 meters squared.
Then we'll come down here and look at V; it is now 6.85 meters long.
We're closer, we're still within that 10 meters.
Then our width, which is G2 to F is here, 10.73.
We're just over that 10 meters, but we're pretty close.
We could obviously dial that in to maximize it.
You can see in this example of our 10 meter by 10 meter square plot
that the horizontal does a lot better covering more surface area and
maximizing that field-of-view. Now as you can see in these examples,
we we're doing pretty specific angles. In order to get those angles,
I highly recommend using some sort of angle locator, angle finder so you can get that right on 62 degrees or 65 degrees.
We resell these, but you can of course buy your own or find your own anywhere,
just so you can get those angles exactly where you want them.
That concludes our video today on the infrared radiometer, choosing the right one for you .
If you have any questions, feel free to comment below and we'll get right back to you on those.
Then if you'd like to also just click right here and you can subscribe to all of our Apogee Instruments videos.
Thank you.
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