We made it! Thanks for supporting Public Lab's 🎈 Mini Balloon & Kite Kit (part of Kickstarter Gold) -- watch the video!

Public Lab Research note


The user 'dhaffnersr' has been placed in moderation and will not be able to respond to comments.
  • 1

CFL Spectral Irradiance Study using Spekwin32

by dhaffnersr |

10 CFL Scans using a 13W 2300K CFL (LTS brand_Generic)

A CFL (compact fluorescent light,) mimics the solar spectrum by super heating an element such as Mercury inside its vacuum chamber, depending on that temperature rating is what the relative luminous flux will be. The mean temperature of the Sun is about 5500K, which is 9440.33 Fahrenheit, of course this is ever changing since many nuclear forces are always occurring within the Sun's core.

This being said, any calibration of a spectrometer that is done with a CFL or any radiant light source, should be viewed as a relative calibration at best. This is because this calibration is solely based on the thermal properties of the light source itself and not the true absolute irradiance factor.

The table below are the emission lines that are used as the reference standard for Zinc, Cadmium and Mercury;

calibration_reference_chart_aug31_C.png

So what I wanted to investigate was the relative luminous flux of the CFL that I use for calibration both with Plab and Spekwin32, and how both those spectral comparisons are effected by the software's algorithms at the same wavelength ranges.

This first plot are the 10 spectral scans I did on Spekwin32 using the laser mount I built, since it's movement is very precise( in mm per step,) I secured the CFL lamp to it (as can be seen in my title picture,) and positioned it 4 feet (121.91cm) away from the detector, keeping the angle of the lamp at 45 degrees pointed down to simulate the sun rising.

All_10_CFL_scans_aug31_spectropic_view_A.png

All_10_cfl_scans_data_chart_aug31_B.png Table.1 Data for all 10 cfl scans, second blue band and green band.

Fig.1 Second Blue peak, zoomed in view

CFL_blue_peak_data_pic1_fig1.png

Fig.2 Green peak, zoomed in view

CFL_green_peak_data_pic1_fig2.png

Now here is Fig.3, showing the CFL scan from Spekwin32 and that of the scan I did from Plab, in the top right corner of the plot, is the quality fit calculations for both spectra's

both_plab_spekwin_CFL_scans_aug31_fig3.png

Both spectral scans have the same wavelength range of 376nm - 766nm, I cut the Plab scan off from 400 to 766nm and it is indicated on the plot.

Fig.4 and 5 are the zoomed in view of both peak comparisons

Blue_peak__both_plab_spekwin_aug31_fig4.png

green_peak__both_plab_spekwin_aug31_fig5.png

Some conclusions from this I think is, in my opinion, CFL calibrations of those done from thermal radiant light sources should be considered as relative calibrations at best and not the gospel, I am finding too many variables in my data and it is increasingly difficult to get consistent results because of this inherent error factor.

I am trying to figure out a mathematical solution that may solve this problem, because I think this is only a problem for devices such as the one's we construct here and perhaps with any home built design, where absolute quality control cannot be assured because of limited resources.

references

file:///C:/Users/dhaff/Downloads/CalibracionEspectrofotometro_24858.pdf - uv/vis spectrometer calibration procedures



spectrometer spectrum-matching spectrography image-compositing image-processing citizen-science field-test spectralworkbench grassroots-science weird-science plots ultraviolet database compact-fluorescent testing spectral-analysis science refinement google google-maps google-earth tests led chlorophyll metadata data-collection data popular-science museum-of-science leds quantitative datalogger civic-science slit-width specification research-notes electrochemical wavelength technique purelab reference hopewell city-point city-point-hopewell-va dhaffnersr david-h-haffner-sr spekwin32 david-h-haffner haffner david ethanol quartz graphs gnu-plot 400nm 400-nm-led technical technical-specs technical-specifications testing-uv-led images-led-testing images-led-testing-400-nm-uv images-test-led-400nm-ultra-violet uv-spectrum-200-400-nm-leds-testing-test-results quartz-cuvettes quartz-cuvette 400nm-led-thru-quartz-cuvette-test electrical-engineering google-search meta-tag meta-tags chlorophyll-testing cool-stuff very-cool-stuff relevant uv-vis uv-vis-ethanol b aspirin uv-vis-chlorophyll dye dyed eosin eosin-y extract portable-laser emission-wavelength wavelengths generic-laser uv-vis-sodium-hydroxide redox width-of-dvd-grating slit-length distance-of-slit bandwidth methylene-blue blank-distilled-water aries emission-wavelength-for-rhodamine-b image-raman-spectrometer google-image-rhodamine-b-samples google-image-raman-spectrometer-homemade plots-spectrometry optical-spectroscopy circular-dichroism-spectroscopy fluorescence-dye photophysik led-testing led-test .

category:verify category:test-limits category:experiment

1 Comments

CalibracionEspectrofotometro_24858.pdf

Here is the PDF file for my reference, there seems to be a problem wth the original one, sorry.


You must be logged in to comment.