Important Info

Apogee’s new DLI-500 meter is designed to measure photosynthetically active radiation (PAR) 400–700 nm and is accurate under all light sources. If you are looking for a low-cost option that is accurate under sunlight and some broadband light sources see our DLI-400 model. In addition to measuring PAR, the DLI-500 meter calculates daily light integral (DLI) and photoperiod. DLI refers to the total amount of PAR or extended PAR (ePAR) incident on a plane in a 24-hour period, expressed in units of moles per square meter per day (mol m-2 d-1). Photoperiod is the total amount of time in which PAR or ePAR is incident on a plane during a 24-hour period and is expressed in units of hours (h). Both DLI and photoperiod influence plant growth and development, and they are often measured in greenhouses and growth chambers to aid in light management and decision making.

The DLI-500 meter has two different screen modes: stored data and live view data. In the stored data screen, it shows the DLI measurement, photoperiod, and which day the data was collected (up to 99 days ago). The live view data screen displays a running average of PPFD from the last 2.5 seconds.

The DLI meters consist of a cast acrylic diffuser (filter), optical filter, photodiode, signal processing circuitry, and an LCD display mounted in an ASA plastic housing. DLI meters are designed for single or continuous measurements of PPFD or ePPFD; DLI; and photoperiod. The DLI meter uses a USB-C cable (included with the meter) to download the stored data as a CSV file to a computer.

Specifications

Calibration Uncertainty
± 5 %

Measurement Repeatability
Less than 0.5 %

Measurement Range
0 to 4000 µmol mˉ² sˉ¹

Long-term Drift
Less than 2 % per year

Field of View
180˚

Spectral Measurement Range(± 5 nm)
389 to 692 nm (sunlight only)

Directional (Cosine) Response
± 5 % at 75˚ zenith angle

Temperature Response
-0.11 ± 0.04 % per C

Response Time
2.5 seconds

Measurement Frequency
3 minutes

Data Log Capacity
99 days (DLI & Photoperiod), 10 days (30 min PPFD/ePPFD averages)

Non-linearity
Less than 1 % (up to 4000 µmol mˉ² sˉ¹)

Stored Data Resolution (PPFD)
0.1 µmol mˉ² sˉ¹ (when ≥ 1000, the screen will not display the decimal)

Stored Data Resolution (DLI)
0.1 mol mˉ² dayˉ¹

Stored Data Resolution (Photoperiod)
0.1 hours

Connectivity
CSV file via USB-C data transfer

ADC Resolution
24 bits

Operating Environment
-40 to 70 C; 0 to 100 % relative humidity

Ingress Protection
IP65

Mounting Compatibility
Brass 1/4-20 threaded mount

Battery Life
Approximately 6 months

Dimensions
1.91 W x 2.31 H x 0.93 D (inches)

Mass
67 g

Warranty
4 years against defects in materials and workmanship

Manufactured
Made in the USA

Video

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