LAI Sensor (Leaf Area Index sensor)

LAI sensor MIJ-15LAI TypeII/K2 : gives you Absolute LAI result


There are two methods for measuring the Leaf Area Index (LAI): direct estimation and indirect estimation. Direct estimation methods include reaping methods and litter traps method. Indirect estimation methods include a method using hemispherical photograph using a camera and a fisheye lens, and a method based on optical assumptions regarding the number of leaves and light attenuation.

In the recent trend, some companies selling instruments to measure LAI named as plant canopy analyzer. The measurement principle used in these instruments are that it detects the ratio of light intensity inside and outside the canopy. Thus, it is necessary to compare the data global solar radiation and the data under the canopy at the same time, based on the absolute value of inside and outside light. In addition, it depends on the azimuth angle of sunlight so that it requires manually performed at the same solar altitude in cloudy weather when the solar radiation intensity is relatively stable for these reasons.
Most significant fact is that these instruments are ignoring PAI such as branches and dead leaves; thus, they are not giving absolute LAI.

The relationship that the ratio of transmitted light correlates with LAI when PAR (400-700 nm) and NIR (700-1000 nm) are reflected and absorbed by chlorophyllin the leaves. MIJ-15 LAI sensor adopted the measurement method by spectroscopy (Patent No. JP5410323B22014.2.5). Therefore, it is possible to stably measure the photosynthetically active radiation (PAR) absorption rate and LAI regardless of the weather. In addition, it is possible to obtain continuous data simply by installing this unit inside the canopy without installing the sensor outside the canopy. When this unit is installed with a data logger, the annual change of LAI can be measured in an unmanned stationary manner. Also, if you use the portable type, you can measure in a wide range while carrying around.

LAI sensor MIJ-15LAI /K2

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 of 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 of 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. 

MIJ15 LAI/K2 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 has 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.

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 Type II /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 Type II /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.



True LAI measurement that reacts only to sites containing chlorophyll

Neglecting PAI    (PAI: Measured values including dead leaves, branches, trunks, etc.)

The world’s only sensor that adopts a relationship in which the intensity ratio of PAR and IR correlates with LAI.

The accuracy is much more accurate than the fisheye lens type

MIJ-15 LAI K2 : Unmanned, continuous, automatic LAI sensor (Required in combination with data logger)


Data Logger MIJ-01

MIJ-15 LAI / K2 need Data Logger 

Mounting Bracket

If you plan to set to the pole you may need mounting bracket.

Related Product

MIJ-15 LAI/P Portable type


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 <±0.5% over 360° at 60°elevation
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 for MIJ-15LAI series (written in English or Japanese)

A canopy photosynthesis model based on a highly generalizable artificial neural network incorporated with a mechanistic understanding of single-leaf photosynthesis
Relationship between Canopy Structure and Community Structure of the Understory Trees in a Beech Forest in Japan
Usability of time-lapse digital camera images to detect characteristics of tree phenology in a tropical rainforest
Development of a Nocturnal Temperature Inversion in a Small Basin Associated with Leaf Area Ratio Changes on the Mountain Slopes in Central Japan
LED Lighting for Urban Agriculture 2016/11/17 (本にて出版)
名古屋大学 2020 3月 プレスリリース
Evaluation of Spatial Light Environment and Plant Canopy Structure
Distributions of photosynthetic traits, shoot growth, and anti-herbivory defence within a canopy of Quercus serrata in different soil nutrient conditions
Correlation Network Analysis Visually Identifies Interactions of Antioxidant Compounds with Plant Growth, Leaf Photosynthetic Performance, and Agronomic Quality in Strawberry
冷温帯落葉広葉樹林におけるLAI季節変化 Seasonal variation in LAI from a cool-temperate deciduous broadleaved forest
The ratio of transmitted near-infrared radiation to photosynthetically active radiation (PAR) increases in proportion to the adsorbed PAR in the canopy
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
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
Novel technique for non-destructive LAI estimation by continuous  measurement of NIR and PAR in rice canopy – ScienceDirect