Figure 1. Calibration of light stimuli by rod suction recordings.
A. Schematic of the optical path. Between the objective and the aperture is a water droplet. The distance from the aperture to the radiometer is ~5 mm. We believe this causes an error in quantitating photon flux due to improper focusing. Inset: a micrograph of the 100µ aperture used to limit area for flux calculation.
B. Variance subtraction for determining µ2/σ2. The top panel shows the total variance and the variance of failures. Failures were chosen according to correlation of each trace with the mean. The bottom panel shows the overlay of the subtracted variance and the square of the mean. The ratio of the traces is one, indicating that the flash delivered, on average, 1 Rh*.
C. Successes and failures chosen by correlation with the mean. Top panel shows all traces and the mean (white). Middle: correlation < 0.51 chooses failures. Bottom: correlation >0.51 chooses successes.
D. Comparison of calibration methods. Each method gave 1.7 Rh* per ms.