The TSL2591 luminosity sensor is an advanced digital light sensor, ideal for use in a wide range of light situations. Compared to low cost CdS cells, this sensor is more precise, allowing for exact lux calculations and can be configured for different gain/timing ranges to detect light ranges from 188 uLux up to 88,000 Lux.
The TSL2591 contains both infrared and full spectrum diodes. That means you can separately measure infrared, full-spectrum or human-visible light. Most sensors can only detect one or the other, which does not accurately represent what human eyes see. This sensor has a 600,000,000:1 dynamic range. You cannot change the I2C address, so keep that in mind.
The TSL2591 contains two integrating analog-to-digital converters (ADC) that integrate currents from two photodiodes. Integration of both channels occurs simultaneously. Upon completion of the conversion cycle, the conversion result is transferred to the Channel 0 and Channel 1 data registers, respectively. The transfers are double-buffered to ensure that the integrity of the data is maintained. After the transfer, the device automatically begins the next integration cycle.
The current draw is extremely low, so its great for low power data-logging systems. about 0.4mA when actively sensing, and less than 5 uA when in power-down mode.
If you are putting a Grove TSL2591 Sunlight / IR sensor in a weather proof container, you should use a far-UV transparent Silica Quartz plate for the window over the sensor. You will also get better readings for the visible and IR TSL2591 readings.
However, remember most plastics and glass are basically impervious to UV radiation (that’s why your Photogray sun glasses don’t work well in a car) so you need to use a special plastic or what we prefer, Silica Quartz. These Quartz JGS1 windows will let the UV through.
This content is from Wikipedia - Spectrum.
A spectrum (plural spectra or spectrums) is a condition that is not limited to a specific set of values but can vary infinitely within a continuum. The word was first used scientifically within the field of optics to describe the rainbow of colors in visible light when separated using a prism. As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum.
The lumen (symbol: lm) is the SI derived unit of luminous flux, a measure of the total "amount" of visible light emitted by a source. Luminous flux differs from power (radiant flux) in that luminous flux measurements reflect the varying sensitivity of the human eye to different wavelengths of light, while radiant flux measurements indicate the total power of all electromagnetic waves emitted, independent of the eye's ability to perceive it. Lumens are related to lux in that one lux is one lumen per square meter.
For some examples: