The Senseca LPPAR01 is a PAR probe for measuring photosynthetically active radiation, designed for indoor monitoring of plant lighting conditions and other applications where photon flux measurement is required rather than simple illuminance.

The probe measures the number of photons reaching a unit area per unit time within the 400…660 nm spectral range. Its measuring range is 0…5000 µmol·m⁻²·s⁻¹, making it suitable for continuous monitoring of PAR levels in controlled indoor environments.

The LPPAR01 uses a photodiode combined with an optical filter and diffuser. The diffuser is cosine corrected, supporting accurate measurement of light arriving from different angles. The specified calibration accuracy is better than 6%, while the cosine response error is also below 6%.

No external power supply is required. Light striking the photodiode generates a photocurrent, which is converted into a potential difference across a shunt resistor. The resulting µV signal can be read using a digital multimeter or a suitable data acquisition device.

Each probe is individually calibrated, and its specific sensitivity factor is marked on the housing. The measured PAR value is calculated using the relationship E = DDP / S, where DDP is the measured potential difference and S is the probe calibration factor.

To achieve approximately 1% reading precision, the probe output should be connected to a digital multimeter with an input resistance greater than 100 kΩ.

The probe assembly includes a photodiode, filter, diffuser, housing, and 5 m cable, supporting straightforward integration into indoor photosynthetically active radiation monitoring systems.

For more information:
https://www.senseca.com/en/product/lppar01-par-probe-for-indoor-photosynthetic-photon-flux-monitoring