Sir,
I have tried for my research to use light emitting diodes, however, I faced the problem to get the right spectra. The companies which are selling the horticultural lights are limited and many of them wont market in India. Others simply gives lights with a range but not with precise wavelength. This acted as an hurdle, as you know specific wavelength create specific effects. I would like to know, how you are measuring the right wavelength? I have tried photoradiometer once for that and it helps. Is there any other method to know the wavelength of the LEDs? Which company lights you are using for your research?
Hello,
simplest way to measure unknown wavelength is to use diffraction grating (DG) and laser with known wavelengths, for example, He-Ne laser. You direct its beam on DG and measure angle of diffraction phi of first or any other orders. Than you do the same for your, well collimated, beam of unknown wavelengths. When you know both angles of diffraction, you use simple relation:
d*sin(phi1) = k*lambda1,
where d is DG pitch, k is order of diffraction. If k is the same for both measurements, you can write:
sin(phi1)/lambda1 = sin(phi2)/lambda2,
so you can find your unknown wavelengths. Good luck.
Diffraction grate + Light etalon
The simplest Diffraction grate is CD-Rom disk.
The simplest Light etalon is UV gas-discharge lamp with Hg - Mercury, vapour.
The Hg vapour spectrum is well documented.
Read well the Plank Constant to under stand as you know already that light and other electromagnetic radiation (w1), for example, consists of particles called photons. To understand what ( as named after German physicist Max Karl Planck (1858–1947), the Planck constant tells us how the energy of individual photons relates to the wavelength of their radiation, as this key equation shows:
Ep = hc/λ
Where Ep is the energy of a single photon (in joules), h is the Planck constant, c is the speed of light in a vacuum, and λ is the radiation’s wavelength.
Moreover, If you are using LEDs for growth responses, illuminate them to a range of intercepted PAR @ 110- 120 µmol m-2sec-1 and measure intensity with help of PAR sensor /light quantum sensor..........
Hi,
It is a pity that your lab doesn't have a simple spectrometer specially if you plan to work with LEDs for a while. There are integrated ones (see mini-spectrometer at Ocean Optics) which can give you quickly (
FYI, this conference paper may help:
https://www.researchgate.net/publication/263415356_Characterization_and_Irradiation_Damage_Tests_of_AlGaN_UV_LEDs_for_Detector_Spaceborne_Calibration
Conference Paper Characterization and Irradiation Damage Tests of AlGaN UV LE...
Dear Kapil, Although PAR is reasonably well defined, plants require other wavelengths to thrive and grow normally. This is an interesting topic, especially if you intend to use narrow radiation bands, Paul.
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