The use of a raised S/P ratio i.e. the ratio to the scotopic to photopic vision is addressed in two technical notices from the Illumination Engineering Society of North America.
The TM12-12 is well suited for mesopic vision (night vision), a combination between photopic (cones) and scotopic vision (rods) in situations with relatively little light e.g. driving in pure street lighting.
The TM 24-13 on the other hand addresses the illuminance topic in view of the visual acuity and visual performance in challenging interiors. In the foreground of this written report is the EVE factor (Equivalent Visual Efficiency).
The main point in both documents from the IES is that raised spectral blue proportion in the illuminance enables improved energy efficiency.
The BTS256-E BiTec Sensor Luxmeter from Gigahertz-Optik is a modern light meter designed for both photometric and scotopic illuminance as well as the luminous color and color rendering. In its latest version, the S/P ratio and EVE factor are also indicated on the display. The BiTec light sensor of the BTS256-E enables precise measurements over a large dynamic range.
For detailed information on this leading-edge multi-sensor device see the BTS256-E.
“I made a presentation about the new light meter for my colleagues at work and in the end of it I said: I like it so much. I was going to have a Xmas picture taken of it and send to my friends and family. Friend of mine is a professional photographer so I called him the next day and booked a Xmas picture of myself and the new light meter and of course I could not resist and added you on the list.”
Kristján Gunnar Kristjánsson
By the way:
All visitors of the Photonics West can get a demonstration of the device at out fair booth.