Mid-infrared hyperspectral microscopy with broadband 1-GHz dual frequency combs

Abstract

Mid-infrared microscopy is an important tool for biological analyses, allowing a direct probe of molecular bonds in their low energy landscape. In addition to the label-free extraction of spectroscopic information, the application of broadband sources can provide a third dimension of chemical specificity. However, to enable widespread deployment, mid-infrared microscopy platforms need to be compact and robust while offering high speed, broad bandwidth, and high signal-to-noise ratio. In this study, we experimentally showcase the integration of a broadband, high-repetition-rate dual-comb spectrometer (DCS) in the mid-infrared range with a scanning microscope. We employ a set of 1-GHz mid-infrared frequency combs, demonstrating their capability for high-speed and broadband hyperspectral imaging of polymers and ovarian tissue. The system covers <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>1000</mml:mn> <mml:mspace></mml:mspace> <mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:math> at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub><mml:mrow><mml:mi>v</mml:mi></mml:mrow> <mml:mrow><mml:mtext>c</mml:mtext></mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>2941</mml:mn> <mml:mspace></mml:mspace> <mml:msup><mml:mrow><mml:mtext>cm</mml:mtext></mml:mrow> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:math> with 12.86 kHz spectra acquisition rate and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mn>5</mml:mn> <mml:mspace></mml:mspace> <mml:mi>μ</mml:mi> <mml:mtext>m</mml:mtext></mml:math> spatial resolution. Taken together, our experiments and analysis elucidate the trade-off between bandwidth and speed in DCS as it relates to microscopy. This provides a roadmap for the future advancement and application of high-repetition-rate DCS hyperspectral imaging.