Dispersion Characteristics of the Multi-mode Fiber-fed VIPA Spectrograph

Abstract A high-resolution (  > 10 5 ), multi-mode fiber-fed spectrograph on large telescopes with a reasonable size is desirable in astronomy. In this work, the dispersion characteristics of Virtually Imaged Phased Array (VIPA) are studied theoretically and experimentally. VIPA spectrograph, fed by optical fibers operating wavelength at 750 ∼ 770 nm, designed built our laboratory. After calibration homemade Yb:fiber ring laser frequency comb (with repetition 808 MHz), measured spectral resolution core diameters $\varnothing =10$?> ∅ = , 25, 50, 105 μ m comparable that single-mode fiber, i.e., }=7.62\times {10}^{5}\sim 8.97\times 7.62 × ∼ 8.97 equivalent transmission efficiencies. This verifies experimentally much less affected input when compared échelle spectrographs. It also found diffraction envelope relies coherence light sources width point-spread function inversely proportional to spatial position detector. Since has no imaging process main direction, insensitive slit or fiber diameter. makes promising instrument attain an ultra-high 3\times 3 ) very telescopes.