Till sidans topp

Sidansvarig: Webbredaktion
Sidan uppdaterades: 2012-09-11 15:12

Tipsa en vän
Utskriftsversion

The 'light scattering fac… - Göteborgs universitet Till startsida
Webbkarta
Till innehåll Läs mer om hur kakor används på gu.se

The 'light scattering factor'. Importance of stimulus geometry, contrast definition, and adaptation.

Artikel i vetenskaplig tidskrift
Författare Jörgen Thaung
C Beckman
Maths Abrahamsson
Johan Sjöstrand
Publicerad i Investigative ophthalmology & visual science
Volym 36
Nummer/häfte 11
Sidor 2313-7
ISSN 0146-0404
Publiceringsår 1995
Publicerad vid Institutionen för klinisk neurovetenskap
Sidor 2313-7
Språk en
Länkar www.ncbi.nlm.nih.gov/entrez/query.f...
Ämnesord Adaptation, Ocular, physiology, Contrast Sensitivity, physiology, Humans, Light, Mathematics, Psychophysics, Reproducibility of Results, Scattering, Radiation
Ämneskategorier Oftalmologi

Sammanfattning

PURPOSE. Paulsson and Sjöstrand have suggested that the light scattering factor (LSF) can be estimated by using the equation: LSF = L/E (M2/M1-1). Here L is the space average luminance of the target, E is the illuminance of the glare source, and M2 and M1 are modulation contrast thresholds in the presence and absence of the glare source. To compensate for change of adaptation. Abrahamsson and Sjöstrand later modified the above equation by introducing a correction factor (CF): LSF = L/E ((CF) (M2/M1-1). The purpose of this study is to analyze the validity of the above equations. METHODS. The importance of stimulus geometry, contrast definition, background luminance, and glare illumination is studied through theoretical analysis and comparison with earlier studies. Stimulus geometry and contrast definition are studied through optical modeling. Adaptation is modeled according to the laws of Weber and DeVries-Rose. RESULTS. The choice of contrast definition may corrupt the result by a factor of 2. At background luminance levels above approximately 10 cd/m2, the Paulsson-Sjöstrand equation agrees well with theory. At lower background levels, the Abrahamsson-Sjöstrand equation is used with correction factors derived from adaptation measurements. Using this equation and earlier published data from glare testing performed at 2 cd/m2, the results are found to be in fair agreement with the light scattering theory. CONCLUSIONS. Glare testing using the Paulsson-Sjöstrand equation is found to be valid as long as the measurements are performed at high luminance levels (above 10 cd/m2), with targets of low spatiotemporal frequencies (e.g., 2 cpd and 1 Hz) and with the use of a properly chosen definition of contrast. At lower luminance levels, the Abrahamsson-Sjöstrand equation may be used with well-derived correction factors.

Sidansvarig: Webbredaktion|Sidan uppdaterades: 2012-09-11
Dela:

På Göteborgs universitet använder vi kakor (cookies) för att webbplatsen ska fungera på ett bra sätt för dig. Genom att surfa vidare godkänner du att vi använder kakor.  Vad är kakor?