Frequently Asked Questions

The following are frequently asked questions about the LI-180. Don't find an answer to your question? Contact us.

Photosynthetically-active radiation, or PAR, is a unitless reference to light that occurs with a wavelength between 400 and 700 nanometers. Photon flux density, or PFD, is a measurement unit describing the number of photons passing through a unit area per unit of time. The LI-180 measures PFD as micromoles of photons per square meter per second (µmol m-2 s-1). PPFD stands for photosynthetic photon flux density, which is PFD (µmol m-2 s-1) that occur in the PAR waveband. In other words, PPFD is the unit of measurement for PAR intensity.
The LI-180 measures light from 380 to 780 nanometers. Measurements are recorded in 1-nm increments with a 12-nm bandwidth. The LI-180 also provides summary measures of total light intensity from the entire 380-780 nm interval, from the 400-700 nm photosynthetically-active radiation (PAR) interval, and in five distinct color band intervals: Near-UV (380-400 nm), Blue (400-500 nm), Green (500-600 nm), Red (600-700 nm), and Far-Red (700-780 nm).

Dark calibration is calibration performed with the 180-02 Dark Calibration Cap. Electrical charge accumulates on the sensor when the instrument is powered on, is moved from a dark environment, or when ambient temperatures change significantly. Dark calibration is performed to mitigate the effects of the electrical charge accumulation on measurement accuracy.

The LI-180 will prompt you to perform dark calibration every time the instrument is powered on, so keep the 180-02 Dark Calibration Cap near the instrument when it is stored. You should also perform dark calibration during periods of continuous operation when temperatures change significantly or if you move from a dark environment to a lighter environment (or vice-versa).

No, the LI-180 is not waterproof.
Yes. The LI-180 is shipped with a 16 GB SD card (part number 180-07), and replacements can be purchased through LI-COR. You may also use your own SD card if it is larger than 1 GB and is formatted in the FAT (file allocation table) file format.
Yes, the LI-180 can be powered from an external power supply. See A Solution for LI-180 Extended Power for different options for powering the LI-180.

Yes. We'll gladly take orders for any of the following components. Replacement batteries (Fuji NP-100) are available from numerous online retailers.

Description Part Number
Dark Calibration Cap 180-02
USB Head-to-Console Cable (3 meter) 180-03
Power Adapter 180-04
Tripod Bracket 180-05
16 GB SD Card 180-07
Wi-Fi SD Card 180-08

Yes. The Fuji NP-100 battery is available from many online retailers. Follow the instructions in the manual to insert the new battery.

The LI-180 measures and records a variety of parameters that describe the light environment, including:

Abbreviation Full Name Unit Description
CCT Correlated Color Temperature K The color radiated by a black-body radiator under different temperatures. CCT has the color that is the closest to the ideal black-body radiator.
CRI (Ra) Color Rendering Index - The average value of R1 ~ R8, where R1 ~ R8 represent the value of eight standard colors as defined by Commission International de l'Eclairage (CIE). A CRI value of 100 indicates the best quality of light for rendering color appearance, while a value of 0 indicates the worst quality of light for rendering color appearance.
R1, R2, ..., R15 Color Rendering Index Varieties - Represents the quality of the light source with the indexes corresponding to 15 standard colors, including: R1: light grey-red; R2: dark grey-yellow; R3: saturated yellow-green; R4: middle yellow-green; R5: light yellow-green; R6: light blue; R7: light purple-blue; R8: light red-purple; R9: saturated red; R10: saturated yellow; R11: saturated green; R12: saturated blue; R13: white skin color; R14: leaf green; and R15: yellow skin color.
Lux Illuminance lx Light flux received by each unit area.
λp Peak Wavelength nm Wavelength with the highest intensity in the measured spectrum.
λpV Peak Wavelength Value mW/m2 Intensity of the peak wavelength in the measured spectrum.
λd Dominant Wavelength nm Used to express the color of the measured light. May be hybridized by the spectrum color of the wavelength and the standard illuminant E(x, y = 0.333, 0.333).
I-Time Integration Time ms Integration time measured by the spectrometer.
x, y, X, Y, Z CIE1931 Chromaticity Chart Color Coordinates - Light color with 2-dimensional plane coordinates (x, y) as defined in CIE Chromaticity Chart CIE1931.
u’, v‘ CIE 1976 Color Coordinate - Light color with 2-dimensional plane coordinates (u', v') as defined in CIE Chromaticity Chart CIE1976.
Duv CIE1960 UV Color Coordinate Difference - UV distance between CIE1960 plane coordinate(s) and Planck’s blackbody radiation with the same color temperature. A value close to 0 indicates the color temperature and color are closer to that of the blackbody radiation. A positive value indicates it is above the blackbody radiation, while a negative value indicates it is below the blackbody radiation.
∆x CIE1931 Color Coordinate Difference - X difference between CIE1931 plane coordinates and Planck’s blackbody radiation with the same color temperature.
∆y CIE1931 Color Coordinate Difference - Y difference between CIE1931 plane coordinates and Planck’s blackbody radiation with the same color temperature.
∆u’ CIE1976 Color Coordinate Difference - U' difference between CIE1976 plane coordinates and Planck’s blackbody radiation with the same color temperature
∆v’ CIE1976 Color Coordinate Difference - V’ difference between CIE1976 plane coordinates and Planck’s blackbody radiation with the same color temperature.
fc Foot-Candle fc Non-SI unit of illuminance defined as lumens per square foot (lm/ft2).
Purity Color Purity % Percent of the dominant wavelength in the standard illuminant. The closer the color purity is to 100%, the closer it is to the dominant wavelength.
IRR Irradiance W m-2 Flux of radiant energy per unit area within the range of a specified wavelength.
PFD Photon Flux Density µmol m-2 s-1 Number of photons per unit area per unit of time.
PPFD Photosynthetic Photon Flux Density µmol m-2 s-1 Number of photons per unit area per unit of time (Photon Flux Density, or PFD) for photosynthetically-active radiation (400-700 nm wavelength range).
PPFD-R PFD in Red Field µmol m-2 s-1 PFD in the 600-700 nm wavelength range.
PPFD-G PFD in Green Field µmol m-2 s-1 PFD in the 500-600 nm wavelength range.
PPFD-B PFD in Blue Field µmol m-2 s-1 PFD in the 400-500 nm wavelength range.
PFD-UV PFD in UV Field µmol m-2 s-1 PFD in the 380-400 nm wavelength range.
PFD-FR PFD in FR Field µmol m-2 s-1 PFD in the 700-780 nm wavelength range.

Yes, not only does it comptue ratios, you can configure the wavebands considered in a ratio, and compute up to four ratios for each sample. Thi is described in Logging Ratios of Spectral Bands

With software version 1.5.0 file types change from .xls (Excel spreadsheet) to .txt (text).

After taking a capture, the LI-180 can record data in two types of files: .jpg (image) and .txt (text). By default, the LI-180 saves data in both types, though you may choose to update the save format to text only. To do this, select the cog icon from a measurement screen or the second page of the home screen and click Save format. Select your desired format and click Yes.

With software version 1.5.0 file types change from .xls (Excel spreadsheet) to .txt (text).

The LI-180 captures two text files: UMOL and ESPD. UMOL files provide a breakdown of spectral composition as instantaneous photon flux density in units of micromoles of photons per square meter per second (μmol m-2 s-1). ESPD files provide a breakdown of spectral composition as spectral power density in units of milliwatts per square meter (mW/m2). To calculate SPD in W/m2, divide the given SPD values by 1000.

See Downloading data from the LI-180 for detailed instructions.
Files cannot be deleted directly on the LI-180 but can be removed when the LI-180 is connected in Mass Storage mode to a PC via USB.
Renaming files directly on the LI-180 is introduced with software version 1.5.0. To rename a file go to Browse and select the file that should be renamed, check the Rename File option and enter the new name for this file. Files can also be renamed when the LI-180 is connected in Mass Storage mode to a PC via USB.

The firmware update can be performed via one of these methods: the USB cable, the 16 GB SD card, or the 8 GB 180-08 WiFi SD card. If one of the methods fails, please try another. However, if you are unable to try an alternative method, retry using the same method following these suggestions:

  • Be sure you downloaded the full update package. It is a compressed folder with several subfolders. Download the files here.
  • Delete the previous update files from the LI-180 before copying the FW1 files to the LI-180.
  • Be sure all files are copied to the LI-180 successfully and no files are missing. Update instructions are here.