Abstract: To provide sufficient sensitivity, spectral resolution and speed of measurement for field environmental measurements in a portable spectroradiometer, a silicon photodiode receives light: (1) having a bandwidth in the range of between 2 and 15 nm (nanometers) from a pivotable concave holographic diffraction grating within the wavelength range of between 250 and 1150 nm at a scanning rate in the range of 20 to 100 nm per second; (2) having stray light of high intensity and undesired frequencies and the shorter wavelength harmonics of the selected frequency range blocked by filters; and (3) having flux of at least 10 microwatts per square meter of diffuser plate for each nanometer of bandwidth. Automatic electrical zeroing is obtained by blocking all light once at the beginning of each scan, obtaining an electrical drift-related signal and using the drift signal to adjust the measured signal during the scan.

Abstract: The resolution of the measuring system of a conveyor type leaf-area meter is optimized when changes are made in the size of the area that is scanned by adjusting: (1) the lens of the scanner; (2) the rate of readout of the pulses from the scanner; and (3) the decimal place of the display unit.

Abstract: To synchronize the belt of a conveyor, a scanner, a fluorescent lamp, and an LED display unit of an area meter, the main AC power supply of the area meter drives the conveyor belt through a synchronous motor and supplies the same frequency of power to a phase locked loop. The phase locked loop provides synchronous pulses of higher frequencies to the scanning system, fluorescent lamp and LED display unit to maintain synchronism. The resolution of the measuring system is optimized when changes are made in the size of the area that is scanned by adjusting: (1) the lens of the scanner; (2) the rate of readout of the pulses from the scanner; and (3) the decimal place of the display unit. Travel from side to side of the belt is avoided by individually adjusting the ends of the pulleys until the belt runs true and an idler which lifts both bottom and top run of the belt when an object moves under it prevents slippage of the belt with respect to the rollers and the bite of the conveyor is adjustable.