5 major performance indicators of spectrometers

Spectroscopy is a branch of optics, which studies the generation of spectra of various substances and their interactions with substances. Spectroscopy is a technology for measuring the intensity of light in the ultraviolet, visible, near-infrared and infrared bands, and is widely used in many fields such as scientific research, teaching, and industry. Fiber optic spectrometers can be used to measure the wavelength and line width of lasers, LEDs, and ordinary light sources, and can accurately obtain the spectral characteristics of the light source to be measured. Generally speaking, the direct result of spectroscopy measurement is a curve composed of many discrete points. The abscissa (X axis) of each point is the wavelength, and the ordinate (Y axis) is the intensity at this wavelength.

1. Wavelength range
The wavelength range is the wavelength range that the Spectrometer can measure. The wavelength range of the new industry's Fiber Optic Spectrometer is 200-1100nm, that is, it can detect from ultraviolet light to infrared light.
The choice of different gratings and detectors will affect the measuring wavelength range of the spectrometer. Generally speaking, the two parameters will check and balance each other. The narrower the wavelength range, the higher the wavelength resolution of the spectrometer. Therefore, the user needs to make a trade-off between the two parameters. If a wide wavelength range and high wavelength resolution are required at the same time, it is recommended to choose a multi-channel spectrometer.
2. Wavelength resolution
The wavelength resolution characterizes the ability of the spectrometer to distinguish wavelengths. The wavelength resolution of the new industry Aurora spectrometer can achieve a maximum of 0.07nm, that is, it can distinguish two spectral lines with an interval of 0.07nm.
3. Noise equivalent power and dynamic range
When the value of the signal is equal to the value of the noise, it is very difficult to distinguish the signal from the noise. Generally, the value of the signal (spectral irradiance or spectral radiance) equivalent to noise is used to characterize the weak light intensity that can be measured by a spectrometer (the Y-axis MIN value). The smaller the noise equivalent power, the weaker the signal can be measured by the spectrometer. Parameters such as the width of the slit, the type of grating, and the type of detector will affect the noise equivalent power.

4. Sensitivity and signal-to-noise ratio
Sensitivity describes the ability of the spectrometer to turn optical signals into electronic signals. High sensitivity helps reduce the influence of the circuit's own noise on the results. At present, the Sunshine series of high-sensitivity spectrometers can achieve a quantum efficiency of 80%.
The signal-to-noise ratio of a spectrometer is defined as the ratio of the average value of the signal to the jitter value (in the horizontal standard deviation) of the signal deviating from the average value when the spectrometer is close to saturation under strong light. The signal-to-noise ratio of the spectrometer is mainly limited by the detector, and the signal-to-noise ratio in the actual measurement can be improved by accumulating the signals through the averaging function of the spectrometer circuit. The Sunshine spectrometer of the new industry uses the Hamamatsu S11510 detector, which can achieve a signal-to-noise ratio of ~450:1.

5. Interference and stability
One of the important differences between an actual spectrometer and an ideal spectrometer is that there are interferences such as stray light inside. Stray light will affect the accuracy of the signal and bring trouble to the measurement of weak signals. The specially designed low stray light optical path can reduce the stray light in the optical path.
The optical path and detector of the spectrometer will inevitably change with the environment. For example, changes in the ambient temperature will cause the wavelength (X axis) of the spectrometer to shift. Special treatment on the optical path and detector can enhance the long-term stability of the spectrometer. Although these special treatments will increase the hardware cost of the spectrometer, the new industry spectrometer still has an ultra-high cost performance.