Microspectrometer based on holographically recorded diffractive elements using supplementary holograms.

Area of Science:

• Optics and Photonics
• Spectroscopy
• Micro-optics

Background:

• Miniaturization of optical instruments is crucial for portable and integrated sensing systems.
• Microspectrometers require high performance within strict size constraints.
• Diffraction gratings are essential for spectral analysis but challenging to fabricate at micro-scales.

Purpose of the Study:

• To design and fabricate a compact imaging microspectrometer with a volume of 11 x 6 x 5 mm³.
• To achieve a spectral bandwidth of 400-1030 nm with high resolution (< 2.5 nm).
• To develop a manufacturing process for a micro-scale holographic concave diffraction grating.

Main Methods:

• Utilized a multi-order concept for spectrometer design.
• Manufactured a 5 mm diameter holographic concave diffraction grating with an 8.6 mm image distance.
• Employed a supplementary hologram recording technique to achieve sub-millimeter point source proximity.

Main Results:

• Successfully realized an imaging microspectrometer within the specified optical volume.
• Achieved a spectral resolution better than 2.5 nm across the 400-1030 nm bandwidth.
• Demonstrated the feasibility of producing a high-quality micro-diffraction grating using the novel holographic method.

Conclusions:

• The developed imaging microspectrometer meets stringent size requirements while delivering excellent spectral performance.
• The innovative holographic recording approach is effective for fabricating critical micro-optical components.
• This technology enables new possibilities for miniaturized spectral analysis in diverse fields.