|Yesterday 02:41 AM|
I think that checking the light intensity as a function of frequency was the intent...
That said, if all you're looking to do is make relative comparisons of spectral intensity, the diffraction grating suggestion I made earlier is all you need to do things like this: (Finnex Planted+ 660nm LED vs 7000k white LED)
In theory you could post-process an image like that into an intensity graph.
That said, with a spectrum-aware probe, you could use some software and actually create a PUR meter instead of a PAR meter... a bit tricky calibration wise, but doable...
|Yesterday 12:43 AM|
You would use the mini spectrometer from Hamamatsu to measure the actual color range claimed for a particular LED, or other kind of light emitter, for example?
Uhm, many different uses with respect to the Tindi Spectrometer...
Fruit ripening detector
Sunscreen pre-warning detection (Solar UV radiation levels)
Plant/Leaf Health levels
Color Calibration and matching
CFL and LED performance measurements
Basic Spectroscopy (molecule fingerprinting)
Mineral and Chemical Detection and classification
Fluorescence spectroscopy (organic compound analysis) biochemical research.
Oil spill verification
Seems like you'd have to be using it professionally to justify the cost. But, other devices in this category are supposedly over $1,000.00. Interesting...
|05-27-2015 10:02 PM|
|mattinmd||To be honest, if you really want to do a spectrophotometer, you're better off with a diffraction grating and a cheap digital camera, webcam, or old smartphone...|
|05-27-2015 09:56 PM|
|05-27-2015 09:37 PM|
|05-27-2015 05:26 PM|
I found this interesting, a micro spectrometer component.
sensitivity from 380nm - 780nm
You'd have to inquire what the cost is. You can plug it into an arduino, which is cool.
|05-25-2015 10:29 PM|
No, I wouldn't change a thing. I was just curious for those that might find it cheaper to obtain the sheets from a local source, rather than pay the shipping costs, which are often as expensive as the product itself. Besides, it sounds like changing the code would be more of a hassle than it's worth.
|05-25-2015 02:19 PM|
You will have to ask Lowes & home depot what the specs on those acrylic sheets. They vary.
The code on the CEP is specifically for 1/8" 2447. You're welcome to change the code but you'll need a PAR sensor, or a calibrate CEP to calibrate.
|05-25-2015 01:54 PM|
Do you think that a white opaque acrylic sheet from someplace like Lowes or Home Depot would suffice, something they sell as a flat sheet shade material for flourescent light fixtures for example. Those are probably about 1/16" thick.
Would you consider that to be the wrong type of material, and/or too thin?
|05-25-2015 01:22 PM|
I found the paint container at Hobby Lobby I think. It might be easier to buy off their online store because you never know what they have in stock at the stores. I'm sure you guys can find another way to build the housing though.
As for the diffuser, it's 1/8" thick 2447 white acrylic. I've only found them online. I've posted the links on the first post.
|05-25-2015 12:54 PM|
Can you advise where you obtained the jars/lids? I recall from reading early in the thread that you had some difficulty at first finding a jar that did not have an obstructed bottom area where there was an embossed area, printed matter, or an uneven surface area, which would distort the light coming through the bottom of the jar, and that it needed to be perfectly flat to achieve the best results.
Also, can you advise your source, and/or the specifications for, the acrylic diffuser material. Some have PM'd me requesting this information so they can build a sensor to the proper specification. I didn't want to advise them to obtain just any acrylic from Lowes or Home Depot, not knowing if there is a particular scientific standard or charactertistic to the acrylic you used.
|05-23-2015 12:31 PM|
For those of you intending to build one of the CEPs...There are a couple of important things I learned when building the sensor that you might find helpful.
I had done what I thought was a really nice job of encapsulating the entire bottom part of the photo diode, from the side rim of the photo diode, all the way down to where the cable begins, making absolutely certain not to get any caulk on the face of the photo diode, so as to not obscure in any way the area where the light is collected through the photo diode surface.
I thought this would seal everything up really well, but the caulk must have acted as a conductor, causing the leads to short, and readings to be way off on the meter. So, I pulled the caulk loose, and cleaned everything up (once the caulk was dry). Readings came back to normal, and the meter starting working perfectly again. Maybe it's the brand of caulk I used...who knows? I used a caulk made by Locktite that comes out white and dries clear. Perhaps another brand, such as GE Silicone, would not have caused this problem...not sure. If you do caulk the leads, make sure you allow several days for it to dry. Perhaps that would have avoided the issue of the leads shorting. But, after waiting at least two days for the caulk to dry, I still experienced the issue with the short, and the meter returning bogus readings. I also tried caulking where the jar lid meets the jar, on the inside. But, drying time was so lengthy, that I abandoned that idea, and cleaned all the caulk up that was on the inside rim of the jar rim and lid.
I finally decided just to caulk the outside surfaces of the jar rim where it meets the lid, also caulking around where the cable meets the cable connector. I also completely caulked the cable connector where it meets the outside top portion of the jar lid where the cable enters the jar. Actually, I made two applications of caulk, allowing the first application to completely dry before moving on to the second application. It seems to have sealed very well.
So, caulking the leads of the photo diode doesn't really seem to be necessary. But, if you do it, I would recommend caulking each lead separately, and trying not to get any between the leads, allowing it to dry a long time, thereby avoiding potential for a short between the two leads of the photo diode, assuming mine wasn't sufficiently dry after two days. When I soldered the leads, I also used heat shrink on each lead, which I thought would sufficiently insulate the leads from a short by the caulk. But, I suppose that enough caulk migrated from one pin entry point into the diode to the other pin entry point, and created a short.
Also, if you want to layer the Rosco Filters the full diameter of the acrylic diffuser, like I did, this may be of interest. I requested some sample sheets from Rosco Filter Company, requesting a sample of each of the specific types that are outlined earlier in the thread. I requested them in the size 6" x 10", so I would have plenty to work with, since I have several PCBs, and figured I might want to build more at a later date. I never received an answer from them after making my request with their customer service department via email. But, low and behold, a sample of each showed up in the mail today, in the size I requested, 6" x 10", and free of charge.
Also, just so you are aware, the face of the photo diode is pushed all the way flush with the Acrylic Diffuser/Rosco Filter Sandwich on the inside of the jar. I then painted the jar because I figured that mine looked better that way, and I figured it would also limit light entering the jar from the sides/lid of the jar, thereby directing light only through the surface of the diffuser. I doubt that it's functionally necessary to paint the side walls/outside lid of the jar, but it can't hurt.
|05-21-2015 03:24 PM|
That's what I figured too...You wouldn't probably need to use it very often, maybe once every four to six months to make sure everything is still on PAR, and if not, time to buy new bulb(s).
Where I can see using it more frequently at first is in designing a fixture for a tank. I've been working on several fixtures over the last several months, some good, some not so good. Without a PAR meter it has all been guess work. You know, little algae blooms here or there, some plants not responding like you had hoped, etc... I'll still have to guess at it when building another fixture, but the PAR meter will sure help in determining if I'm on the right track.
|05-21-2015 01:37 PM|
|mistergreen||A 9V battery will last you years. You won't be using the meter all that much. At first, you'll be measuring everything but then it'll go in the drawer|
|05-21-2015 12:30 AM|
Great idea engineering that kind of voltage latitude into the design. It's nice to know we can use a power supply (ie: brick) to power the CEP if we want to, and not be particularly concerned about burning it up.
Just curious, do you have any estimate of how long the CEP will last on 9v battery power?
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