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.

Abstract: To measure the density of a foilage canopy, an elongated average-light measuring instrument includes an elongated diffuser, an elongated quartz rod with a uniform diffusing groove in it between it and the diffuser and a photodiode at one end so that radiation hitting the diffuser enters the quartz rod and is transmitted to the photodiode to provide a measure of average light entering the length of the instrument. To digitize light instead of sensing average light, another embodiment includes a plurality of separate light entrances positioned along the length of the quartz rod and a scanner that scans across the rod or a uniform diffusing groove and circuitry that digitizes the electrical signal from the photodiode periodically in accordance with the position of the light scanner on the groove.

Abstract: To provide a printout corresponding to the integral of the current or voltage from any of several different instruments, a printing integrator includes a voltage-to-frequency converter which receives current or voltage through a replaceable buffer amplifier and provides pulses to a counter at a rate proportional to the amplitude of the input current or voltage. The output of the counter is printed in rows along with the time of printing and an indication of the state of the battery.To generate pulses at a rate proportional to an input signal, a charge is periodically supplied to a feedback capacitor of an operational amplifier from a storage capacitor in the voltage-to-frequency converter, and an input current derived from the signal decreases the charge in the feedback capacitor until the output potential of the operational amplifier drops below a level set on a comparator, thus generating a pulse and initiating another discharge from the storage capacitor into the feedback capacitor.