Spectrometer Zero Order Light Recycling
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Solution Overview
Problem
Spectrographic measurements are limited by the uncollected zero order light, which reduces signal-to-noise ratio and measurement precision due to its absorption in current spectrograph designs.
Innovation Solution
Collecting the zero order light using a lens or mirror and redirecting it through a fiber optic back into the spectrometer's input slit for re-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the zero order light is absorbed to prevent scattering and contamination, then the measurement reliability is improved, but the signal-to-noise ratio deteriorates due to loss of photons
Solution Approach 1:
A beam splitter is introduced as an intermediary component to separate the zero order light from the diffracted light paths. The beam splitter directs the zero order light to a dedicated detector while allowing the diffracted light to proceed to the spectral detector, thus preventing contamination while preserving the zero order photons for measurement
Solution Approach 2:
The zero order light path is given dual functionality: it serves both as a reference beam for calibration purposes and as a source of additional signal information. The same optical path that was previously discarded now provides both system alignment reference and enhanced signal detection
2Device complexity
If the zero order light is discarded to simplify the optical path, then the device complexity is reduced, but the productivity deteriorates due to loss of useful signal
Solution Approach 1:
The optical detection system is segmented into distinct functional channels: one for diffracted light spectral analysis and another for zero order light detection. This segmentation allows each channel to be optimized independently, with the zero order channel providing additional signal without interfering with the primary spectral measurement channel
3Measurement precision
If more light is collected and redirected through additional components, then the signal-to-noise ratio is improved, but the device complexity increases due to additional optical elements
Solution Approach 1:
The zero order light, which was previously considered waste or harmful, is utilized to serve the system's own measurement needs. By detecting the zero order light that has interact with the sample, the system obtains additional signal information without requiring external calibration sources or additional illumination
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach increases the rotational Raman signal by 20% in atmospheric LIDAR systems by recycling the zero order light, enhancing measurement precision.
Implementation Method 1
a lens or mirror and focused into a fiber optic
Implementation Method 2
a lens or mirror and focused into a fiber optic
Implementation Method 3
diffraction grating based spectrograph
Data Source
AI summary
Spectrographic measurements are often limited by the amount of light that is available. Photons that are not collected or measured reduce the signal to noise and therefore reduce measurement precision. This invention collects the zero order light and sends it through the spectrometer again. In an atmospheric LIDAR, the zero order recycling is estimated to increase the rotational Raman signal by an additional 20%. A grating based spectrometer where the zero order light is collected by a lens or mirror and focused into a fiber optic that sends the light to the input slit where it is directed into the spectrometer again. There can be a plurality of recycle fibers. The detector can be either a single linear array or a two dimensional array such as a CCD or CMOS camera.