Study of light source for laver culture vessel.

The light source used for an artificial culture vessel of layer thalli on a larger scale was in-vestigated. Fluorescent lamps and H. P. mercury lamps (especially thallium mercury lamps) were chosen from standpoints of output, light efficiency and the shape of the bulb. Incandescent lamps were eliminated from consideration of output and light efficiency. These lamps were designed in a longitudinal water dipping style and prepared with a protective tube corresponding to the higher culture density of the saver thalli. The test results of each lamp's characteristics are as follows: 1) The fluorescent lamp gives uniform lighting on overall length but its output is only enough for low culture densities, and the temperature of the bulb surface is too low to attain optimum lighting when it is placed under-water. 2) The high pressure mercury lamp and thallium mercury lamp were designed for uniform lighting through an extended illuminating tube in spite of the demand for high voltage for activa-tion or some separate illuminating tubes connected electrically parallel and inserted in one lamp. These lamps have the most suitable characteristics for a light source under high culture denseties of culture vessels. The relationship between light intensity (L), distance from light source (X)and culture density of layer (C) was shown as the following exponential equation according to experimental results. L=L0•10-1.72×10-4(C+1.16)x L0 means light intensity on the bulb surface. For the present condition, L=5.5klx, C=100g (dry)/100l, L0=240klx are chosen. X was set at around 50cm. These numbers were realistic from an engineering standpoint, applying dipping style's high pressure mercury lamp or thallium mercury lamp as a light source, and therefore these numhers were determined to be the desired ones from the culture test.