What par meter can give me Par and Wavelength graph?

[ps2cho]

What's the cheapest one that will do both so I can measure both intensity and wavelength for my LED and T5 combo?

 

I want to be able to compare how it performs and know when to change bulbs/trying different bulbs out

[evilc66]

Only way you are going to read the spectral content of a light is with a spectrometer, and those start at about $2000 for a decent visible light spectrometer. But, once you start adding fibers, cosine correctors and calibration sources, expect to be closer to $3000.

 

Once you get a spectrometer, there is no guarantee that you will have PAR/PUR measurement capability. That's all done in software, so you need to find a spectrometer that has that software feature. Ocean Optics does, but even their USB2000 isn't cheap. It would be cool if they sold their STS spectrometer to the public in low volume (currently only to OEMs with minimum quantities), as they are around $1000 and tiny.

 

And no, the Seneye Reef doesn't do real spectral analysis. All they are using is an RGB light sensor, so they are just measuring the basics.

[evilc66]

To continue this, there are some cheaper alternatives out there to the $2K+ spectrometers, but there are some limitations associated with them. As a general rule, to get the costs down, the resolution suffers due to the sensors picked. Ocean Optics has the Spark module that can be found online for $500, but you get about 4.5-9.0nm resolution depending on the model. It's not a bad thing, as most of us don't need super fine resolution, but once you start spending a little more, you get close to 1nm resolution.

 

Software is also a limitation. Ocean Optics has one of the best suites for optical analysis, but it's an additional cost above and beyond the cost of the spectrometer. Same with the PUR/PAR add-on. Other spectrometers will include the software, but it just does the typical spectral analysis (wavelength, peak, dominant, CCT, CRI, etc...).

 

Public Labs has their cheap $10 spectrometer, but it's severely limited. All it is is a chunk of CD that is used as a diffraction grating that splits the light up into it's constituent wavelengths that is read by a webcam or cell phone. That right there is the biggest issue. Digital cameras are not sensitive to short wavelengths of light (violet to royal blue), so it's not really all that accurate in the range that we typically need. Also, every manufacturers camera is a little different, so comparing readings from one user to the next will be near impossible.

[Matteo]

Only way you are going to read the spectral content of a light is with a spectrometer, and those start at about $2000 for a decent visible light spectrometer. But, once you start adding fibers, cosine correctors and calibration sources, expect to be closer to $3000.

 

Once you get a spectrometer, there is no guarantee that you will have PAR/PUR measurement capability. That's all done in software, so you need to find a spectrometer that has that software feature. Ocean Optics does, but even their USB2000 isn't cheap. It would be cool if they sold their STS spectrometer to the public in low volume (currently only to OEMs with minimum quantities), as they are around $1000 and tiny.

 

And no, the Seneye Reef doesn't do real spectral analysis. All they are using is an RGB light sensor, so they are just measuring the basics.

I made a spectrometer in Chem 202 last year using a shirt box and some mirros