Cavity-enhanced direct frequency comb spectroscopy

A broadband picometer resolution visible CCD spectrometer based on virtually imaged phased array technology

“…For a Gaussian input beam, when the reshaping of the input beam by the collimating lens is negligible, the light intensity distribution at the position ( x , y ) on the CCD detection plane can be written as: 6,24–27 where I in ( λ ) is the input beam power spectral density, exp(−2 f c 2 y 2 / f 2 W 2 ) is the envelope of light intensity along the y direction, ((1 − Rr ) 2 + 4 Rr sin 2 (π Δ / λ )) −1 describes the VIPA dispersion, Δ = 2 tn e cos( θ in ) − 2 t tan( θ in )cos( θ i ) y / f − t cos( θ in ) y 2 / n e f 2 is the optical path difference between adjacent beams within the VIPA etalon, and exp(−( x − λf ( λ 0 − λ )/ dλ 0 cos( θ d )/cos( θ ig ) fλ /cos( θ d )π W ) 2 ) describes the grating dispersion. The intensity distribution is the product of these four parts.…”