CHEMICAL FILTERS FOR NARROW BAND UV IRRADIATION BETWEEN 235-NM AND 300-NM

Abstract— Six chemical filters are described. Bands of 10–20 nm half width are isolated at the following wavelengths: 235–240–252–260–277–294 nm. The filters transmit at the center of their band pass between 1.5 and 30 per cent of the incident radiation. Average photon fluence rates of 15–150 ergs mm‐2 sec‐1 (0.3 × 10‐3 to 3.5 × 10‐3μE cm‐2 sec‐1) are obtained with a 500 W high pressure mercury arc focussed on a 10 cm‐2 area. Under these conditions, the flux transmitted in the near i.r., visible and near u.v. does not exceed 1 per cent of the total flux transmitted. The flux transmitted outside a 40 nm band centered at the maximum does not exceed 1 per cent of the total transmitted flux for four of the filters, this flux goes up to 4 per cent of the total for the 294 nm filter and to 10 per cent for the 235 nm filter. Copyright © 1969, Wiley Blackwell. All rights reserved