Compact double-pass Echelle spectrometer employing a crossed diffraction grating.

Area of Science:

• Optics and Photonics
• Spectroscopy
• Instrument Design

Background:

• Classical Echelle spectrometers utilize multiple dispersive elements.
• Compact and robust spectrometer designs are crucial for various applications.
• Crossed diffraction gratings offer combined dispersive functionalities.

Purpose of the Study:

• To design and implement a compact, robust Echelle-inspired spectrometer.
• To utilize a double-pass setup with refractive elements and a crossed diffraction grating.
• To evaluate the performance and resolving power of the developed spectrometer.

Main Methods:

• A double-pass optical setup was employed.
• A crossed diffraction grating, a superposition of two perpendicular blazed gratings, was utilized.
• Refractive elements were used for collimation and imaging.
• Experimental tests were conducted using an entrance pinhole and a single-mode fiber.

Main Results:

• The spectrometer achieved a resolving power of over 300 in the 400 nm to 1100 nm spectrum with a 105 µm pinhole.
• Utilizing a single-mode fiber increased the resolving power to over 1000.
• The design demonstrated robustness due to a rigid objective group.

Conclusions:

• The developed Echelle-inspired spectrometer is compact and robust.
• The crossed diffraction grating effectively combines dispersive functionalities.
• High resolving power is achievable, with further enhancement using single-mode fiber, albeit with increased acquisition time.