LAI Sensor (Leaf Area Index Sensor)

LAI sensor MIJ-15LAI TypeII/K2

MIJ15 LAI will give you Absolute LAI result


  • The world’s only sensor that adopted the relationship that the spectral ratio of PAR and IR correlates with Leaf Area Index (LAI).
  • Regardless of cloudy weather, fine weather, instantaneous LAI measurement on the spot has been completed.
  • Capable of Absolute LAI measurement Result
  • No PAI (Plant Area Index) counting so avoiding influences from dead leaves, branches, trunks remain.
  • MIJ-15 LAI/K2 can continuously and automatically observe LAI value changes over time.  (Data logger must use)
  • Two choice from below type
    /K2 stands for fixed – point observation
    /P stands for portable handheld measurement


Major LAI Meters
Measurements of Leaf Area Index (LAI) divided into two types direct and estimating measurements.
Measuring by Reaping or  leaf litter trap is the direct measurement.
By estimating leaf volume and light decay based on optical estimation by using hemispherical photograph is the estimating measurement.

After leaving K2 for about a year, you can check the seasonal change of LAI.
This is the best feature: one and only sensor that can measure the seasonal change of LAI without leaving it is only sensor in the world. Others are analyzers or meter that require human intervention, not sensors.

Disadvantage of major Plant Canopy analyzer 

To see the LAI results, we will need to have two plant Canopy analyzers; this is because LAI result  must need to compare the transmission of light ratio both inside and outside canopy at the same time.  This means, it is depending on the absolute value of inside and outside light; thus the at least two instruments need to set at inside and outside.

There is no stable atmosphere condition so researchers must care solar radiation intensity every single test. In fact, solar radiation intensity is mostly stable at cloudy weather but do you want to choose cloudy weather for field experiments? Even though solar radiation intensity is stable at cloudy weather condition, you still need to care the sun height, to gain the good LAI results. To do so  instruments need to place at same sun height. But can you keep setting at same height?  

Do you know Plant Area Index (PAI) influencing LAI results?
This is because general LAI sensor involve branch and dead leaves these elements cannot called leaf but major LAI meter ignoring  the fact that these obstacles messing LAI results so it is impossible to correct exact LAI value.

LAI sensor MIJ-15LAI Type2

MIJ15 LAI Sensor provide with 5m cable so it must use with data logger. Sensor itself is same as PAR sensor MIJ14 which has a reputation for its extremely small long-term drift and robustness; this sensor intended to be permanently installed field and operated unattended.
This design ha a proven track record of less than ± 0.1%/3 year drift unless destroyed in an accident. Much more durable than LAI sensors made by other companies.

LAI is slowly changing parameter so that researchers may annoyed because when measuring manually, you have to do a huge amount of work both in terms od time and effort. But MIJ-15LAIK2 is only set under the canopy and you can wait till year end.
Many LAI instruments simultaneously measure the intensity of light under the canopy and the intensity of light outside the canopy, measurement principle is that the obtained ratio correlates with LAI. Therefore, the effect of the growth of branches and trunks blocking the light directly affects the measured value. Also, in the autumnal tree species, the leaves without chlorophyll also block the light. In other words, it is unavoidable that dead leaves are counted as LAI.

On the other hand, in MIJ-15LAI, the measurement principle is that the ratio of the near-infrared light of chlorophyll contained in leaves and the spectral transmittance of PAR correlates with LAI so it do not count dead leaves, branches, trunks, electric wires and other artificial objects that have no chlorophyll. 

Absolute quantity of LAI
MIJ-15LAI/P and MIJ-15LAI Type2/K2 will let researchers to determine absolute quantity of LAI by measuring the spectral ratio of sunlight transmitted through plant canopy.


We used the measurement by spectroscopy.
(Patented NO.JP5410323B22014.2.5)
PAR(400-700nm) and NIR(700-1000nm) will be reflect and absorption occur at chlorophyll inside leaf so the transmitted light ratio is correlated with LAI.
MIJ-15LAI TypeII/K2 gives numerous hopes for the feature research.
You do not need to think about weather condition and LAI and PAR can be measured  just set under the canopy or leaf. Also you only need to have one MIJ-15LAI TypeII/K2 so price will be reasonable and it is portable so you can measure easily or traditionally set it at canopy; LAI annual change can be measured with data logger .


Measurements Range 0〜5,000μE

Voltage (Calibration Coefficient labeled as ###.##μE/mV)

System Sensitivity:
・PAR/10mV at 2300uE

・NIR/5mV   at 1300uE

LAI arithmetic expression LAI=2.80In(NIR/PAR)+0.69*

*Kume et al.(2011) J Plant Res124:99_106.
Temperature effect <±0.1%/DEG

PAR & NIR: uE(μmol・S-1・m-2)

LAI: dimensionless

Response  0.2u/Sec
Incidence angle characteristics <±1.5% at 0〜79°(< -50%Peak at 80〜89°)
Angle of rotation characteristics <±1.5% at 0〜79°(< -50%Peak at 80〜89°)
Material Case:A5052, Coating: anodized aluminum, Diffuser: PTFE
Temperature Range -40〜80℃
Shape 126mm(W), 60mm(D)×49mm(H)
Weight 500g
pin assignment White/output+, Black/output-
Standard Pack MIJ-15LAI TypeII/K2 (With 5m cable) 

Reference: Mixed Japanese and English journals

2008年度 九州大学森林生態圏管理学講座(演習林) 研究発表会 プログラム
NIR・PAR の連続測定による生育期間を通じたイネ群落 LAI の非破壊計測法の開発
近赤外光・光合成有効放射比の連続測定によるイネ群落の非破壊 LAI 計測法の開発
Varietal & regional differences in rice canopy development evaluated by non-destructive LAI measurement
日本農業気象学会全国大会講演要旨/Proceedings of International Symposium on Agricultural Meteorology  (日本農業気象学会全国大会講演要旨/Proceedings of ISAM)
The ratio of transmitted near-infrared radiation to photosynthetically active radiation (PAR)
increases in
proportion to the adsorbed PAR in the canopy
Adaptive frequency scaled wavelet packet decomposition for frog call classification
日本農業気象学会全国大会講演要旨/Proceedings of International Symposium on Agricultural Meteorology   (日本農業気象学会全国大会講演要旨/Proceedings of ISAM)
冷温帯落葉広葉樹林におけるLAIの季節変化Seasonal variation in LAI from a cool-temperate deciduous broadleaved forest
A Special Relationship between Canopy and Understory Leaf Area Index in an
Old-Growth Cool-Temperate Deciduous Forest