Different Types of Sunlight Lamps
As discussed above, full sunlight bulbs cannot reproduce the exact sunlight spectrum. However, there are available commercial bulbs that approximate this spectrum to a very satisfactory degree.
Although incandescent light provides us with a smooth and continuous spectrum, a 100 Watt standard incandescent bulb has a color temperature of only 2850K with a high proportion of yellow and red color. A type of incandescent bulb coated with neodymium is marketed as sunshine lamp, although the color temperature is far less than the limit of 5000K. However, it is important to note that the visual spectrum of the human eye does not fit the solar spectrum. So, these lamps may actually be beneficial, although not matching the sunlight.
Compact Fluorescent Lamps or CFLs are more versatile. They are available in a wide range of temperatures reaching the values of 5000 and 6000K as well. Fluorescent lamps display continuous spectra combined with discrete lines or spikes. The availability of such a wide range of CFLs is due to the mix of phosphors inside the tube. Each of them emits a discrete color, thus the addition of extra phosphors increases the CRI of the lamp (~80) along with its price.
LEDs can also be used to mimic the natural sunlight through a device called the “LED solar simulator." Although LED technology is very promising, no real market exists on this area yet.
Other types of lamps, such as the Mercury-Vapor lamps and High Intensity Discharge lamps (HID), may have good color temperature but their light spectrum appears fractured.