To resolve the problem of mismatch between the target spectra viewed by remote sensors and spectra of calibration source, and effectively guarantee the calibration accuracy, the target spectra simulation technology is a very promising evolution trend for calibration sources. The development and applications of calibration source technology used to simulate target spectra in scene in the domain of optical calibration were presented. The design of a spectrally tunable light source based on digital micromirror device (DMD) was described as an example to illuminate the design method of sources based on spatial light modulator. Besides possessing the function of target spectra simulation, this novel calibration source can be combined with the standard detector. So it is useful to improve the calibration accuracy of sensors, and can be extremely promising for calibrating hyperspectral imagers.