leds.mspct: Spectral irradiance for diverse LEDs

In aphalo/photobiologyLEDs: Spectral Data for Light-Emitting-Diodes

Spectral irradiance for diverse LEDs

Description

A collection of emission spectra of light-emitting-diodes from different suppliers.

Usage

leds.mspct

led_arrays.mspct

Format

A "source_mspct" object containing 74 "source_spct" objects.

In each of the member spectra, the variables are as follows:

• w.length (nm)

• s.e.irrad (W m-2 nm-1)

An object of class source_mspct (inherits from generic_mspct, list) with 3 rows and 1 columns.

Details

The leds.mspct and led_arrays.mspct objects contain "source_spct" objects with spectral irradiance data, for single channel and multichannel LEDs, respectively. As the exact distance from LED to cosine diffuser and/or the driving current vary among spectra for different LEDs, members of leds.mspct have been all normalized to the wavelength of maximum spectral energy irradiance. In contrast, spectra in led_arrays.mspct have not been normalised as comparisons among channels of each array are meaningful, even if approximate.

When the details of the measurement conditions are know, these are stored as metadata attributes. In any case, it needs to be taken into account than even in these cases measurements have not been done in an optical bench, so values of spectral irradiance are subject to errors due to possible misalignment. The shape of the spectra, in contrast can be relied upon as measurements were done with well calibrated instruments.

The output of LEDs at a given current decreases as their temperature increases. The wavelength at the peak of emission can depend on the temperature and current, but shifts tend to be only a couple of nanometres. In LED arrays with heterogeneous LED chips or white LEDs based on secondary emission from phosphor the shape of the spectrum can slightly change depending on the drive current and temperature.

There is variation among LEDs of the same type, specially with respect wavelength and light output. The data included are for individual LEDs and can be expected to differ to some extent from the typical values in the manufacturers specifications. Some of the LEDs for which data are included are only of historical interest as their production has been discontinued, usually replaced by new types with enhanced performance. When known, the approximate "vintage" is provided in the metadata.

Some LEDs are "generic" ones which lacked detailed data sheets at the time of purchase, or even lacked a manufacturer's type denomination code. For them, the metadata is necessarily less detailed.

The spectral data are not expressed at constant wavelength intervals. Not only the intervals vary in the raw data from the array spectrometer, but in addition function thin_wl has been applied to reduce the storage space needed. In brief the wavelength interval has been increased as much as possible in those regions of the spectrum that lack detailed features (such as linear slopes and wavelength regions with zero light emission). The algorithm used preserved the location and height of significant energy emission peaks, i.e., the global peak and clear local peaks.

Note

Please see the help page for led_brands for LED suppliers' contact information. Please see the metadata in each spectrum for other information. These metadata are stored as attributes of the individual source_spct objects and can accessed with functions comment, getWhatMeasured, getWhenMeasured and getHowMeasured. Many of the spectra also contain information on the measurement procedure accessible with getInstrDesc and getInstrSettings.

See Also

oo_maya_leds

Examples

library(photobiology)

names(leds.mspct)

names(led_arrays.mspct)

leds.mspct$Nichia_NS6L183AT_H1_sw

cat(getWhatMeasured(leds.mspct$Nichia_NS6L183AT_H1_sw))

peaks(leds.mspct$Nichia_NS6L183AT_H1_sw, span = 100)

wl_range(leds.mspct$Nichia_NS6L183AT_H1_sw)

wl_stepsize(leds.mspct$Nichia_NS6L183AT_H1_sw)

intersect(LedEngin_leds, blue_leds)

leds.mspct[intersect(LedEngin_leds, blue_leds)]

aphalo/photobiologyLEDs documentation built on Dec. 1, 2024, 4:15 a.m.