Light solutions for light metrology

About the company

Hehkulab is a Finnish, Helsinki-based engineering and consulting company with over thirty years of combined metrology experience [1-19].

Hehkulab helps companies and laboratories to make more accurate light measurements, while increasing their time and cost efficiency. For the clients, this comes with minimal effort, investments, and changes to their existing processes.

Contact us: contact@hehkulab.fi


Fisheye camera system
Alexander Kokka
Managing director, D.Sc. (Tech.)
Formerly a research scientist at the Finnish National Metrology Institute for optical quantities. Doctoral dissertation on Spatial and spectral corrections for integrating sphere photometry and radiometry.
Fisheye camera system
Tomi Pulli
Technical director, D.Sc. (Tech.)
Former branch manager for photometry at the National Metrology Institute for optical quantities in Finland. Doctoral dissertation on Improvements in spectroradiometric measurements and applications.
  1. Maksim Shpak et al, "Optical temperature measurement method for glowing microcomponents" International Journal of Thermophysics 31, 1762-1770 (2010)
  2. Maksim Shpak et al, "Optical temperature measurements of silicon microbridge emitters" Applied Optics 49, 1489-1493 (2010)
  3. Tomi Pulli et al, "A method for optimizing the cosine response of solar UV diffusers" Journal of Geophysical Research: Atmospheres 118, 7897-7904 (2013)
  4. Timo Dönsberg et al, "A primary standard of optical power based on induced-junction silicon photodiodes operated at room temperature" Metrologia 51, 197-202 (2014)
  5. Maksim Shpak et al, "Luminance meter for photopic and scotopic measurements in the mesopic range" Measurement Science and Technology 25, 095001 (2014)
  6. Timo Dönsberg et al, "New source and detector technology for the realization of photometric units" Metrologia 51, S276-S281 (2014)
  7. Hans Baumgartner et al, "A temperature controller for high power light emitting diodes based on resistive heating and liquid cooling" Applied Thermal Engineering 71, 317-323 (2014)
  8. Timo Dönsberg et al, "Optical aperture area determination for accurate illuminance and luminous efficacy measurements of LED lamps" Optical Review 23, 510-521 (2014)
  9. Maksim Shpak et al, "Mathematical limitations of the CIE mesopic photometry system" Lighting Research & Technology 49, 111-121 (2015)
  10. Tomi Pulli et al, "Advantages of white LED lamps and new detector technology in photometry" Light: Science & Applications 4, e332 (2015)
  11. Hans Baumgartner et al, "Natural and accelerated ageing of LED lamps" Lighting Research & Technology 48, 930-942 (2016)
  12. Hans Baumgartner et al, "Temperature invariant energy value in LED spectra" Applied Physics Letters 109, 231103 (2016)
  13. Tomi Pulli et al, "Nonlinearity characterization of array spectroradiometers for the solar UV measurements" Applied Optics 56, 3077-3086 (2017)
  14. Alexander Kokka et al, "Fisheye camera method for spatial non-uniformity corrections in luminous flux measurements with integrating spheres" Metrologia 54, 577-583 (2017)
  15. Timo Dönsberg et al, "Predictable quantum efficient detector based on n-type silicon photodiodes" Metrologia 54, 821-836 (2017)
  16. Alexander Kokka et al, "Development of white LED illuminants for colorimetry and recommendation of white LED reference spectrum for photometry" Metrologia 55, 526-534 (2018)
  17. Tomi Pulli et al, "Out-of-range stray light characterization of single-monochromator Brewer spectrophotometers" Atmosphere-Ocean 56, 1-11 (2018)
  18. Alexander Kokka et al, "Validation of the fisheye camera method for spatial non-uniformity corrections in luminous flux measurements with integrating spheres" Metrologia 56, 045002 (9pp) (2019)
  19. Alexander Kokka et al, "Flat-field calibration method for hyperspectral frame cameras" Metrologia 56, 055001 (8pp) (2019)