A film-solarimeter was examined for field use. It integrates the solar radiation from the light transmittance of the film coated azo dyes. Relations between the film transmittance and the exposed solar energy were studied to make calibration curves under the field condition. At the same time, the variance of fading reaction of each film was investigated before and after the exposure. In order to evaluate field application, film-solarimeters were deployed to measure the amount of solar radiation inside the canopy of deciduous broad-leaved forest through three seasons. Several characteristics, merits and limits are found. If choose the appropriate time ranges and the possible happenings will be understood, the film-solarimeter must be an effectual and easy method to measure the amount of solar radiation in the experimental field.
