Light Measurement
Ocean Optics spectrometers and accessories can be configured easily into small-footprint and portable systems for measuring the absolute or relative irradiance of radiant sources such as incandescent lights, gas-discharge lamps, flat panel displays and more. Solar irradiance measurements are also possible.
To optimize setups, users can combine their spectrometers with sampling devices including optical fibers, integrating spheres and cosine correctors. Software can be used to process data for absolute irradiance, photometry, color, peak metrics, photosynthetically active radiation and more.
Featured:
Flame Spectrometer
Thermally stable spectrometer with interchangeable slits for measurement flexibility; ideal for wide range of UV-Vis through Shortwave NIR applications
Overview
Upwelling is radiation — either reflected solar or emitted terrestrial — that is directed upward from the Earth’s surface. Downwelling radiation is radiation that is directed toward the Earth’s surface from the sun or atmosphere. The relationship between the two (albedo) can be used to derive spectral information from vegetation, forest canopies, sea beds and more.
Spectrometer
An HR4000 spectrometer with an HC-1 grating is one option for upwelling and downwelling measurements (a two-channel Jaz system is an alternative that offers slightly different advantages). The HC-1 is a variable-blazed grating that covers the 200-1050 nm wavelength range; optical resolution is ~1.5 nm (FWHM) with a 50 µm slit as the entrance aperture. An OFLV-200-1100 order-sorting filter eliminates second- and third-order effects.
Sampling Optics
The spectrometer connects to a patch cord that screws into the CC-3-UV cosine corrector. The CC-3-UV can be used as part of a configuration for measuring absolute spectral irradiance. You’ll need a light source to calibrate the absolute spectral response of the system and OceanView spectroscopy operating software to calculate spectral intensity and photopic data in lumens, lux or candela. An alternative to the CC-3-UV is a Gershun tube, which has fixtures for adjusting the area of light from 1° to 28° and attaches directly to the spectrometer or to an optical fiber.
Upwelling/Downwelling System Components
The setup described here is just one option available for upwelling/downwelling measurements. For example, the previously mentioned Jaz spectrometer eliminates the need for a PC and would make it more convenient to switch from upwelling to downwelling measurements or to capture both measurements simultaneously.
Here are the items in the example setup:
| HR4000 | High resolution spectrometer. We recommend configuring the spectrometer with an HC-1 grating for extended range (200-1050 nm), a 50 µm slit as the entrance aperture and a DET4-200-1100 detector with variable longpass filter and quartz window |
| Light Source | UV-NIR light source used to calibrate the absolute spectral response of a radiometric system |
| QP400-2-UV-VIS | Premium-grade patch cord for collecting signal |
| CC-3-UV-S | Sampling optic attaches to optical fiber to collect signal from 180° field of view |
| OceanView | Spectrometer operating software |
Emission spectrum of a VUV lamp shows clearly defined peaks, with good SNR performance.
Spectrometers are easily configured for relative irradiance measurements of visible and other light sources.
Solar irradiance spectrum with identification of absorption bands of atmospheric elements.
