Extended Data Fig. 10: Measurement of photon flux within the POA.
From: Violet-light suppression of thermogenesis by opsin 5 hypothalamic neurons
a, Schematic of experimental setup for measuring intra-cranial photon flux as described in Methods. b, Holt–Sweeney microprobe consisting of a pulled optic fibre with an attached transparent spherical diffusing tip. Scale bar, 100 μm. c, Measurement depths and probe path within cranium. d, Absolute photon flux within mouse cranium with OPN5 action spectrum superimposed (adapted from2 with data points from4). Top blue trace represents surface flux and, at the λmax of OPN5, is about 3.4 × 1013 photons cm−2 s−1. At the maximum 4.0 mm depth (grey trace), the flux at the λmax of OPN5 is approximately 9.5 × 1010 photons cm−2 s−1. e, Relative photon flux normalized to surface measurements. Each trace is expressed as mean ± s.e.m. from n = 3 mice.
