Figure 1
The Brillouin ocular analyzer system. (A) The tabletop Brillouin imaging system in the laboratory at Massachusetts General Hospital in Boston. (B) Brillouin measurement of a volunteer by an operator, using the portable Brillouin ocular scanner in the clinical setting at IROC in Zürich, Switzerland. (C) Schematic of the Brillouin imaging system, composed of three parts: a light source, a human scanning interface built on a modified slit-lamp platform, and a high-resolution, two-stage VIPA spectrometer consisting of two crossed-axis VIPA etalons. OI: optical isolator; PD: photodiode; BS: beam sampler; PMF: polarization maintaining single-mode fiber; SMF: single mode fiber; λ/2: half waveplate; λ/4: quarter-waveplate; M: mirror; Obj. L: objective lens; PBS: polarizing beam-splitter; S1/S2: optical shutters; Ref: reference materials; C1/C2: cylindrical lens; A1/A2: achromatic lens; S1/S2: shutters; V1/V2: VIPAs. (D) Probe beam geometry. (E) Representative Brillouin signals from the cornea recorded in vivo using the EMCCD camera in the spectrometer. (F) An eye-tracking camera view showing locations of axial scans (red dots). (G) A representative axial (depth) scan profile of measured frequency shifts across the cornea and anterior chamber of a healthy volunteer. (H) A typical Brillouin elasticity map of a normal cornea.
