Hi, my name is John Huber and in this video we will be going over a quick set of instructions
on how to set up a laboratory spectroradiometer for reflectance measurements.
Now for these reflectance measurements you're going to need a few things.
You're going to need, obviously, your spectroradiometer, the computer that it will interface with,
a reflectance standard, a stable light source,
in my case I'm going to use a reflectance probe with a flashlight built into it,
and the unit's fiber optic cable.
Now, as far as reflectance standards go, I've got a sheet of spectralon here.
It is the same material as our AS-004 reflectance standard.
So this material reflects all light within the spectroradiometer's sensitivity range
and so it will work very well as a light reference.
So the first step to setting up your spectroradiometer will be,
first, to make sure you've got StellarNet SpectraWiz installed and working on your computer.
After that you're going to want to make sure your spectroradiometer is plugged in, which mine is.
And then after that, the next step will be to plug in the fiber optic cable.
So you'll want to note the end that says it plugs into the spectroradiometer.
It has a little arrow pointing to where the spectroradiometer should be.
So I'm going to go ahead and plug that end in first.
And then, if you're just using the fiber optic cable for your reflectance measurements,
you'll want to position it in a fixed position for the duration of your measurements.
In my case, I'm going to put it into this reflectance probe here,
which will also serve as my light source.
It's very important that you have a stable light source throughout your measurements.
So once you've got everything hooked up, the next thing you'll want to do is start up SpectraWiz.
And to do that, we do recommend that you run it as an administrator.
So I'm going to go ahead and navigate to its install directory on the C Drive --> Program Files --> StellarNet --> SpectraWiz.
And then the executable is this SWD file. I'm going to right click it and run it as an administrator.
Doing this makes sure that the program has the privileges that it needs to function properly.
Otherwise, Windows is going to create some false files in another directory that you'll need to delete for the program to work right.
So once you've got StellarNet SpectraWiz running, you're going to want to make sure you're in "Scope" mode.
So select "View" and "Scope mode".
And once you've got that set up, you'll want to make sure your light source is on.
So I'm going to turn the little flashlight in my probe here on.
And then you're going to position your fiber optic cable over your reflectance standard target.
Now once you've got it positioned over the target, your next step is to optimize the integration time.
So, when you're optimizing the integration time,
your goal is to make sure that this graph here occupies as much of the Y-axis here as possible, without cutting off at the top.
So right now the graph is too low. I'm going to show you what it looks like when it's too high.
So you go "Setup" --> "Detector Integration Time"
and to make the graph go higher, you simply increase this integration time number.
To make it go lower, you decrease it. So I'm going to increase it by too much, just as an example.
So as you can see, the graph is cutting off slightly at the top here,
which means my integration time is too high, I need to bring it down.
So I'll go "Setup" --> "Detector Integration Time". Going to bring it down a little bit to 1450 here.
Now your integration time is going to vary depending on the brightness of your light source.
The brighter the light source, the lower your integration time will be.
So in this case, this integration time looks like it's good.
It's occupying a good portion of the Y-axis, but it's not being cut off at all.
So we're going to let it sit for a while to make sure it's stable, which it looks like it is.
So once it's stable, your next step is to obtain a dark scan.
So the key to obtaining a good dark scan is just to make sure that there is no light getting into your spectroradiometer.
So for this procedure, I'm going to unplug the fiber optic cable and then cover the opening port.
And when you do this, you should see a nice flat light at the bottom.
It's okay if there are some tiny bumps in it. We're going to flatten those out with the dark scan.
So, I prefer to release old dark scans first.
This is optional, but it usually it leads to better dark scans over all, in my experience.
So to release an old dark scan, you'll want to right click this button here with the dark scan icon.
And when you do that, you'll notice that a small square forms in the lower left corner of the graph.
That means that the old dark scan has been erased.
And when you're ready to save a new dark scan, just left click the button here.
You'll notice the line is nice and flat along the bottom and the value down here is bouncing very close to zero.
It'll vary by a bit, but it should always remain close to zero.
So now that we've got a good dark scan, I'm going to plug the fiber optic cable back in,
and then I'm going to replace the probe over the standard,
and then we're going to make sure the integration time still looks good,
which it still occupies most of the Y-axis here, so that's still a good integration time.
So once you've got your dark scan and your integration time set, the next thing you need to do is go into "Transmission" mode.
So go "View" --> "Transmission".
And now the next step after that is simply to click this light reference button here,
and that will establish your reflectant standard as the standard for 100% reflectance.
And at this point, you are now ready to start taking reflectance measurements.
So I'm just going to take a quick measurement off of the black table top here.
And as you can see, the black table top is absorbing most of the visible spectrum,
but is beginning to reflect the Far - red spectrum beyond 700 nanometers, which we'd expect to see.
So once you have a good spectrum and you're satisfied with it and you want to save it,
you go up to "File" --> "Save" --> "Sample".
You'll pick a location to save your file and give it a name. I'm going to call this one test.
And now this window comes up.
It allows you to define your starting wavelength, your ending wavelength, and your wavelength increments.
For this file, I'm going to just keep the starting and ending wavelengths and then change the wavelength increments to one nanometer.
Once you've done that, you click "OK" and your spectrum is saved.
And now if you want to open your spectrum up in a program like Microsoft Excel, all you need to do is open up Excel,
click "File" --> "Open" --> browse to the location where you saved your file,
and then you want to make sure that Excel is looking for all files and not just Excel files.
Find your file and open it.
And then you want to make sure it's "Delimited" by "Spaces".
Click "Finish" and there's our spectrum file.
And that concludes the brief tutorial on how to take a reflectance measurement. Thank you for watching!
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