Transmissive Diffraction Element Spectral Apparatus with Folded Optical Path
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Solution Overview
Problem
Current spectral apparatuses face challenges in achieving high resolution and efficiency while being compact, as they require large diffraction elements and suffer from optical aberrations, making it difficult to separate longitudinal modes of optical comb light sources effectively.
Innovation Solution
A spectral apparatus design utilizing a transmissive type diffraction element in a Littrow arrangement, combined with a specific optical system configuration that allows light to reciprocally travel between mirrors, maximizing diffraction efficiency and minimizing aberrations, enabling high-resolution spectral separation without the need for bulky reflective elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large diffraction element is used to achieve high resolution, then the wavelength resolution improves, but the apparatus size increases and optical aberrations occur
Solution Approach 1:
The patent combines multiple diffraction elements (gratings) in a compact folded optical path configuration, allowing the light to interact with multiple smaller diffraction surfaces rather than requiring a single large diffraction element. This merging approach achieves the cumulative diffraction effect of a large element while maintaining a compact apparatus footprint.
Solution Approach 2:
The patent introduces a folded optical path using mirrors to reflect light back and forth through the diffraction element multiple times. This transforms a linear spatial arrangement into a multi-dimensional folded path, effectively increasing the optical interaction length without proportionally increasing the physical apparatus dimensions.
2Measurement precision
If a large diffraction element is used to achieve high resolution, then the wavelength resolution improves, but optical aberrations increase
Solution Approach 1:
The patent divides the diffraction function across multiple smaller diffraction elements rather than using a single large element. Each smaller element introduces fewer optical aberrations, and the cumulative effect across multiple elements achieves the required resolution without the aberration problems of a single large element.
Solution Approach 2:
The patent uses multiple passes through the diffraction element (excessive action) to achieve higher resolution than a single pass would provide. By reflecting light back and forth through the same compact diffraction element multiple times, the apparatus accumulates the diffraction effect without proportionally increasing aberrations.
3Measurement precision
If a reflective type diffraction element larger than 300 mm is used to separate longitudinal modes, then the spectral resolution improves, but the apparatus becomes bulky
Solution Approach 1:
The patent combines multiple compact diffraction elements in series within a folded optical path, replacing the need for a single large reflective diffraction element. This merging of multiple smaller components achieves the required spectral resolution while maintaining a compact apparatus size.
Solution Approach 2:
The patent transitions from a reflective type diffraction element to a transmissive type diffraction element combined with mirror reflections. This substitution allows the use of smaller, more compact components while achieving the same spectral separation function, reducing the overall apparatus volume.
4Measurement precision
If conventional spectral apparatus design prioritizes signal-to-noise ratio, then detection accuracy improves, but absolute efficiency and output are reduced
Solution Approach 1:
The patent implements a folded optical path where light passes through the diffraction element multiple times in succession, maximizing the utilization of incident light. This continuous useful action through multiple passes increases the absolute efficiency and output while maintaining the spectral resolution required for accurate detection.
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 design achieves high-resolution spectral separation with improved efficiency, allowing for the separation of longitudinal modes and generation of continuous wave or arbitrary waveform light sources, while reducing the apparatus size and minimizing sensitivity to distortion, thus enhancing the signal-to-noise ratio and absolute output efficiency.
Implementation Method 1
a transmissive type diffraction element configured to diffract the light from the first optical system
Implementation Method 2
a first mirror configured to reflect the light diffracted by the transmissive type diffraction element
Implementation Method 3
a second mirror configured to reflect the light reflected by the first mirror and diffracted by the transmissive type diffraction element, and configured to make the light reciprocally travel between the first mirror and the second mirror via the transmissive type diffraction element
Data Source
AI summary
The present invention provides a spectral apparatus for spectrally separating light including a predetermined wavelength, including a slit that the light enters, a first optical system configured to collimate the light from the slit, a transmissive type diffraction element configured to diffract the light from the first optical system, and a second optical system including a first mirror configured to reflect the light diffracted by the transmissive type diffraction element, and a second mirror configured to reflect the light reflected by the first mirror and diffracted by the transmissive type diffraction element, and configured to make the light reciprocally travel between the first mirror and the second mirror via the transmissive type diffraction element.