Abstract

The emission properties of “cool” and “warm” white light-emitting diodes were studied in the context of low-cost spectrophotometry. The suitability of pulse-width modulation as a method to control the diode brightness was examined. Both types of light-emitting diode demonstrated emission standard deviation minima at a pulse-width modulation frequency greater than 2000 Hz. The functional wavelength ranges of the light-emitting diodes were approximated using the linearity of brightness as a function of pulse-width modulation duty-cycle and the root mean squared deviation from mean for absorbance measurements. Both light emitting diode types demonstrated good stability in absorbance measurements over long operation times. The “warm” light emitting diode demonstrated a broader range of wavelengths useful for spectrophotometry.

摘要

在低成本分光光度法的背景下研究了“冷”和“暖”白光发光二极管的发射特性。检查了脉冲宽度调制作为控制二极管亮度的方法的适用性。两种类型的发光二极管都在大于 2000 Hz 的脉宽调制频率下显示出发射标准偏差最小值。使用作为脉冲宽度调制占空比的函数的亮度线性和与吸光度测量平均值的均方根偏差来近似发光二极管的功能波长范围。两种类型的发光二极管在长时间操作中都表现出良好的吸光度测量稳定性。“暖”发光二极管展示了更广泛的波长范围，可用于分光光度法。