DESIGN AND PERFORMANCE OF THE OKAZAKI LARGE SPECTROGRAPH FOR PHOTOBIOLOGICAL RESEARCH

TLDR

A computer‑operated spectrograph was recently constructed at Okazaki, Japan. The spectrograph uses a 10‑m horseshoe‑shaped focal curve spanning 250–1000 nm, with specimens positioned in microcomputer‑controlled threshold boxes that automatically set wavelengths, fluence rates, fluences, and timing, and includes an optical fiber system for remote irradiation. The device achieves a linear dispersion of ~0.8 nm cm⁻¹, delivers photon fluence rates of 5 × 10¹⁵ photons cm⁻² s⁻¹ at 300 nm and 1 × 10¹⁶ photons cm⁻² s⁻¹ at 600 and 900 nm, maintains a spectral half‑width of ≤5.5 nm, and limits stray light to ~10⁻⁵ of the main peak within ±100 nm.

Abstract

Abstract A computer‐operated spectrograph was recently built at Okazaki, Japan. Different specimens can be placed on a horseshoe‐shaped focal curve (10 m long) covering a wavelength range of 250 to 1000 nm so they can be irradiated simultaneously. The linear dispersion is about 0.8 nm/cm. The photon fluence rate on the focal curve is 5 x 10 15 . photons x cm ‐2 x s ‐1 at 300nm and 1 x 10 16 photons x cm ‐2 x s ‐1 at 600 and at 900 nm. The spectral half width is 5.5 nm or less on the focal curve. The stray light content is about 10 ‐5 of the main peak at the peak wavelength ± 100 nm. Specimens are set in microcomputer‐controlled threshold boxes so that wavelengths, photon fluence rates, photon fluences and timing of irradiations are controlled automatically according to a pre‐programmed schedule. An optical fiber system is also provided for remote irradiations.