Abstract: A light regulation system is provided wherein the light output of a fluorescent lamp(s) is regulated in accordance with the RMS value of the lamp arc current which is automatically adjusted to maintain a referenced ambient light level or arc current. The ballast and associated lamps of the system receive the full line voltage until the lamps are ignited and thereafter the current thereto is automatically limited by limiting the amplitude of the ballast current during the part of each AC voltage half wave that the lamps are ignited. Control between the minimum light level, wherein a minimum arc current flows during each half cycle, to the maximum light level is accomplished by permitting the minimum arc current which flows during the "lamps on" period of each half wave to increase to maximum arc current over a part or all of the period of each half wave that the lamps are on.

Abstract: Apparatus and method for calibrating the points in a large Reseau grid with extreme accuracy. The method includes superimposing a smaller calibrated master grid on the large grid, comparing the location of the point on the large grid with the location of the corresponding point on the master grid, generating the comparison data, translating the master grid to another location, comparing the points on the two grids, and repeating the translating and comparing steps until the entire large grid is calibrated. A laser interferometer is used to determine the amount of translation of the master grid with the requisite accuracy.

Abstract: This invention relates to a method and apparatus for growing plant life under controlled conditions including gas discharge lamps with electronic means utilized to provide predetermined pulses of electric current to the lamps so that bursts of radiant energy are supplied to the plant life, these bursts of energy being of a duration in the order of microseconds and at a periodicity that is favorable to the plant growing processes. The radiant energy supplied to the plant life is within the spectral range required for photosynthesis and is uniform to the photoreceptors of the plant life.