Handheld Devices
Quick, reliable and easy measurements in the field or laboratory
General questions

  • Where can I check FluorPen/SpectraPen software compatibility with different Windows versions?
  • The compatibility information are in specification of each handheld device on our website in download section.

  • Is there a function "RESET TO FACTORY SETTINGS" in the FluorPen/SpectraPen software?
  • Unfortunately, there is no such function in the software. The only possibility is to reload the device firmware, which we recommend just in emergency cases and only on the recommendation of the support team.

  • Are all handheld devices equipped with both communication modules - USB and Bluetooth?
  • New versions 110 of AquaPens, FluorPens, PlantPens and LaiPen are equipped with both communication modules (AP 110, FP 110, NDVI 310, PRI 210, N 110 and LP 110).
    The old versions 100 always come with just one communication module - either USB or Bluetooth.
    All vesrions of SpectraPens and PolyPens are supplied always just with USB communication module.

  • Maximum charging current of the battery is 0.5 A. Does it mean, that only charger with the same current can be used for battery charging?
  • No, also power banks, USB chargers, etc. with higher charging current e.g. 2 A can be used. Maximum charging current of Pen battery indicates that it can take only 0.5 A from the charger even the charger has higher charging current. Higher charging current does not cause any damage to the battery or device.

  • My computer does not recognize that the device is connected when using the USB communication. Can you help on this?
  • This issue could be probably caused by one of following point:

    1. Damaged cable – please check the cable connector, which goes to Pen. This part of the cable is very fragile and may be easily destroyed. Have a look into the connector. There are four equally long and perpendicular pins. In case you have doubts, please contact our support team. Please note that the cable in not under warranty.
    2. USB driver – this point is related only to AquaPen, FluorPen, PlantPen and LaiPen devices. Driver installation is necessary for proper USB connection. Go to Device Manager ˃ Ports (COM). In case there is warning mark at the Pen port, please update/install driver. Driver is on USB installation disc or available on PSI website.
    3. Unfunctional USB port – problem with connection could be caused also due to malfunction in computer. Go to Device Manager ˃ Ports (COM). In case there are no visible devices connected in ports, please reconnect manually the Pen to another port of your computer or to another computer.

  • I transferred the measured data to a PC via the FluorPen/SpectraPen software. Now I am trying to save or export it to txt format, but the Export icon at FILE menu is not functional (disabled). Do you have an advice to enable the key and its function?
  • You need to activate the software by entering the registration serial number. You can do it in the menu Help-Register. Your serial number is on the installation flash drive in the SN.txt file. The procedure is also described in the user manual.

  • An error message appears when downloading data via FluorPen/SpectraPen software to my computer.
  • Version of the FluorPen software is not compatible with downloaded data. Please install the current software version from PSI website (download section on the website of particular device). Before installation remove all older software versions including desktop shortcuts from your computer. Note that new installed version needs to be registered for full activation.

  • There are no calculated parameters within fluorescence protocols (OJIP, NPQ or LC) after downloading data using FluorPen software.
  • Your FluorPen software is not installed correctly and the file necessary for calculations is missing. Please install the current software version from PSI website (download section on the website of particular device). Before installation remove all older software versions including desktop shortcuts from your computer. Note that new installed version needs to be registered for full activation.

  • I am unable to download the data from the device to the Excel spreadsheet: please, could you tell how can I do?
  • In the Fluorpen software go to Export and export the data to txt file. Then in Excel go to Data and Import Data from Text. In this way you export data directly to Excel and process then further. For more information about text import to excel please follow Microsoft office support.

  • Is it possible to export just part of measured data or all data must be exported?
  • It is possible to export all data or one selected measurement. Mark the selected measurement by mouse before export. Then go to Export menu and choose Selected only.

  • What should I do when the display on my device shows just FP-Boot and when switched on and does not do anything after that?
  • The firmware update hepls to solve this issue. Please contact the support team with the serial number of your device. The appropriate BXN file will be sent to you accordingly. Please note that all data will be erased from the device memory during firmware update. It is highly recommended to back up the data before starting the update. Please update your device firmware as follows:

    1. Connect the device to the PC
    2. Select menu Setup->device ID
    3. Select menu Setup->Update firmware from file
    4. Select the downloaded BXN file

    Firmware updating procedure is also depicted in the Operation Manual.

  • I have a problem with downloading data from my handheld device. When the device gets to the end (100%) of the download, it gives an Error: TFpData:parse Data0 -> unknown ID 0. And then just sits with the spinning circle and there is no way to get data off the unit.
  • This error means that the data in internal memory is corrupted. The reason for that could be for example power failure (battery dead or removed) during data saving procedure. If there are no important data it could be easily solved by erasing the memory. If you need the data please do following:
    Please take a look into the folder where FlourPen software is installed (default is Program Files/PSI/FluorPen) and send the file error-data.bin to the support team. Make sure you have enabled “Show hidden files”.

  • Referring to the GPS Module - what is the accuracy of the location registration?
  • The GPS module works with accuracy of <1.5 m in 50% of trials.

  • We have a problem to activate the external GPS Module. How can we activate it?
  • Please check the Manual provided. To correctly attach the GPS coordinates, it is essential to set time correctly on the device and on the PC. It is using time zone settings from the computer so you should check that too. Also check that Garmin is set in Mass Storage mode.

  • What is the function of cosine corrector in PAR-sensor or light sensor of SpectraPen?
  • Cosine corrector is used for collecting light from 180 degrees angle. The sensor itselfs has a small angle in which light is accepted. It is about 30 degrees. It is used for relative and absolute spectral intensity measurements, for emissive color applications, and for evaluation of light sources such as LEDs and lasers.

    Fluorometers (AP, FP and MP)

  • Is the FluorPen software capable of recording used light intensitis?
  • Yes, new versions of handheld fluorometers (AP 110 and FP 110) are capable to record information about set light intensities.

  • In which units is measured fluorescence in handheld devices?
  • Fluorescence is measured in relative fluorescence units, also called arbitrary units (A.U.).

  • What is measuring time of fluorescence protocols?
  • It differs for single protocols: Ft takes about 100 ms, OJIP and QY about 1-2 seconds, NPQ and LC protocols take up to few minutes.

  • How big is the memory in FP/MP/AP device? How many measurements can be saved in the device internal memory?

  • Ft: up to 149,000 measurements
    QY: up to 95,000 measurements
    LC1: up to 3,000 measurements
    LC2: up to 3,500 measurements
    LC3: up to 2,600 measurements
    OJIP: up to 1,100 measurements
    NPQ1: up to 800 measurements
    NPQ2: up to 500 measurements

  • Can you explain meaning of the Flash pulse (f_pulse)?
  • This function serves for setting of flash pulses intensity. The flash pulses are weak pulses, which are able to induce the minimal chlorophyll fluorescence (Fo or Ft) and are crucial for PAM method. It takes only 30 µs and the maximum intensity is 3000 µmol photon.m^-2.s^-1. It means 30 µs * 3000 µmol.m-2.s-1 = 0,09 µmol.m-2 per pulse is the maximal intensity of the f_pulse.

  • How should I adjust correctly the Flash pulse (f_pulse) settings prior to fluorescence measurement?
  • The optimum value of f_pulse can be identified for instance with the QY measurement. Before initiating the QY measurement it is recommended to set the pulse color based on the type of measured organism, if the device allows it and intensity of F_pulse on 70%. QY measurement should be performed with dark adapted sample. If you use the cuvette version of the AquaPen, make sure that you use always fresh 4 ml of culture for each individual measurement, as the culture can be inhibited after measurement. Or wait given time period between the individual measurements to ensure relaxation of photosynthetic apparatus during the dark adaptation of the sample prior next measurement. The f_pulse setting recommended by the manufacturer is 30%. Perform QY measurement with different intensities of f_pulse and choose the f_pulse intensity at which you reach the highest QY value.
    Usually is recommended to increase the intensity of f_pulse in case of sample with very low chlorophyll density. Please note that high intensities of f_pulse can cause undesirable “actinic effect” resulting in increase of F0 value - in this case F0 isn´t real dark adapted F0 and QY value will be lower. The f_pulse intensity at which the highest value of QY is reached is the optimal one for your culture.

  • Can you explain meaning of the Super pulse (F_pulse)?
  • This function serves for setting intensity of the Super pulse. Super pulse is able to induce maximum chlorophyll fluorescence (Fm). 100% of intensity equals approximately 3000 µmol.m-2.s-1.

  • How should I adjust correctly the Super pulse (F_pulse) settings prior to fluorescence measurement?
  • The best way to recognize the optimum intensity of F_pulse is to perform OJIP measurement. During OJIP measurement solely F_pulse (super/saturating pulse) is used for ChlF measurement. OJIP measurement should be performed with dark adapted sample. If you use the cuvette version of the AquaPen, make sure that you use always fresh 4 ml of culture each individual measurement, as the culture can be inhibited after measurement. Or wait given time period between the individual measurements to ensure relaxation of photosynthetic apparatus during the dark adaptation of the sample prior next measurement. The F_pulse setting recommended by manufacturer is 70%. Perform OJIP measurement with different instensities of F_pulse. The F_pulse intensity at which the highest value of Fv/Fm is reached is the optimal one for your sample.

  • Can you explain meaning of the Actinic pulse (A_pulse)?
  • This function serves for setting intensity of actinic pulses. Actinic light is basically the ambient light in which the plants or algae are growing. 100% of intensity equals approximately 1000 µmol.m-2.s-1.
    New version AP 110 and FP 110 has calibrated actinic light and it is set directly in µmol.m-2.s-1.

  • What does it mean when the device shows "low val" on the display when measuring fluorescence?
  • “Low val” means low value of fluorescence signal. Samples with very low concentration of chlorophyll show low fluorescence signal. If it is possible concentrate the sample by centrifugation, filtration or sedimentation for amplification of fluorescence signal.

  • How should I adjust the measurement when I get „over-flow“ error message during fluorescence measurement?
  • The „over-flow“ error message means that the chlorophyll fluorescence signal is above the range of detection. This issue can be fixed by diluting of the sample (liquid samples) or in case the sample can not be diluted (plant leaves), increase the intensity of used pulses.

  • Why measure dark-adapted samples?
  • Dark adaptation is a technique recommended in some chlorophyll fluorescence measurements to assure reference point relative to various measurements. You get higher photosynthetic performance when measuring dark-adapted samples, because in dark all reactions centers of PSII relax and are ready for incoming light energy. In light-adapted sample some of the reaction centers are saturated with the ambient light and therefore cannot accept all photons of the incoming light and you get lower QY value. You could of course compare QY values of light-adapted samples, but the result could be affected by light conditions before the measurement.

  • How long dark-adaptation time is recommended?
  • Duration of dark adaptation depends on species, in general it is between 5 and 30 minutes.

  • Can I measure Ft and QY in presence of light (without dark condition)?
  • Basically all measured fluorescence parametres can be acquired either after dark adaptation or in the light adapted state. Ft refers to Fo if the leaf sample is dark-adapted (Fo refers to minimal level of fluorescence in dark adapted state). QY measured in the light is equal to Fv´/Fm´ and it provides an estimate of the PSII maximum efficiency within light-adapted material in contrast to Fv/Fm which is an estimate of the PSII maximum efficiency within dark-adapted material. Explanation of particular parameters: Fo - minimum fluorescence signal (when all PSII centres are in the open state) from dark-adapted material; Fo' - minimum fluorescence signal (when all PSII centres are in the open state) from light-adapted material; Ft - fluorescence signal at any point between Fo' and Fm', in other words instaneous fluorescence which is affected by the level of light the object is exposed to; Fm - maximum fluorescence signal (when all PSII centres are in the closed state) from dark-adapted material; Fm' - maximum fluorescence signal (when all PSII centres are in the closed state) from light-adapted material.

  • Do the Ft values change within one measurement or between measurements? Should I do some kind of calibration or programming before measuring?
  • The value can change slightly (in range 10%). If the change within one measurement is bigger, it is recommended to set the f_pulse intensity lower. Strongly increasing Ft value within one measurement means, that f_pulse is too strong and causes unwanted "actinic effect" (= photochemistry starts). Fluorescence measurements do not require calibration.

  • Why Fo and Fm values measured by OJIP protocol do not correspond to Fo and Fm values achieved by other fluorescence protocols (Ft, QY, NPQ and LC) afforded by AquaPen or FluorPen?
  • The OJIP curve is measured differently compared with Ft, QY, NPQ and LC protocols. Therefore Fo and Fm values cannot be compared. Ft, QY, NPQ and LC are measured with measuring pulses using PAM – Pulse Amplitude Modulated technique of measurement. OJIP curve is non-PAM technique measured in continuous light and Fo value is measured at very early time point of OJIP. It has sense to compare just relative parameters like Fv/Fm measured by PAM nad OJIP type of measurement.

  • Is it possible to calculate ETR from data measured?
  • Yes, it can be calculated by the Light Curve data using this equation: YII*PAR*0.84*0.5.

    Spectrameters (SP, LM, RP and PA)

  • Can you shortly explain the difference in between the PolyPen RP 410, SpectraPen SP 110 and SpectraPen LM 510 ?
  • PolyPen RP 410 measures reflectance on leaves or other plant samples. It is capable of calculation of various reflectance indices (some of them are pre-programmed). It features an integrated light source and a leaf clip. SpectraPen SP 110 is a spectrometer without spectroradiometric calibration. It features a SMA905 light fiber port. It is intended for measuring reflectance, transmitance and light wavelength. SpectraPen LM 510 is a spectroradiometrically calibrated spectrometer with integrated cosine corrector. It measures absolute values of light intensity in uW/cm2/nm and photon flux density in umol/m2/s/nm. It calculates: irradiance (uW/cm2/), PAR (umol/m2/s), illuminance (Lux), CIE1931 coordinates, CCT (L).

  • Is there any difference in measuring absorbance and transmittance with the PolyPen and with the SpectraPen?
  • PolyPen is equipped with an internal light source. Thus it is a complete system for leaf reflectance measurements not requiring any additional accessories. SpectraPen is a simple spectrophotometer with no in-built light source.

  • Can I obtain trustworthy results when measuring with PolyPen RP 410 or PlantPen if my plant samples are small, smaller than the optical entrance of these devices?
  • Yes it is possible to measure smaller leaves with minor limitation. The leaf clip is equipped with white coating that is used for calibration. When you use smaller leaves the white coating become "visible" for the instrument and influence the results. This can be fixed by putting some black material as a background for the leaf to cover white coating during measurement.

  • Does the PolyPen RP 410 or PlantPen work also on monocot leaves with a prominent midvein?
  • These devices have been tested and used for monocot species. However it is important to remember that veins can indeed cause some interferences during the measurement and that the first leaves of same age should be cross-compared and, in an ideal case, the method should be standardized to the same part of the leaf.


  • What is the purpose of the PAR sensor (Light Meter) ?
  • Integrated Light Meter serves for direct digital readouts of Photosynthetically Active Radiation (PAR) in the range from 400 to 700 nm, the span in which plants use energy during photosynthesis. PAR is measured as Photosynthetic Photon Flux Density (PPFD), which is indicated by units of quanta (photons) per unit time per unit surface area. The sensor has a uniform response to photons within the 400 - 700 nm waveband.


  • The measuring cuvette doesn’t fit into the AquaPen’s cuvette slot. Which cuvettes are compatible with the AquaPen?
  • Unfortunately, it might happen occasionally that the cuvette doesn’t fit into the cuvette slot because the slot is too tight. The tight slot enables to place the cuvette in the fixed position in order to improve the measurement accuracy. Usually, we use common 1 cm plastic visible range cuvettes with 4 clear faces from Kartell distributed through Merci (in the Czech Republic).
    A hint – the AquaPen may be used also without the measuring cuvette and the sample may be pour directly into the measuring slot as the slot is waterproof. The slot needs to be washed out thoroughly after each measurement to avoid biomass fouling of the glass walls.

  • In the AquaPen-C there is a function CAL. OD. How long it takes to execute once? For calibration, should I put the cuvette in the slot, blank or filled with water?
  • If you want to measure the optical density, OD calibration should be performed after every swich ON of the device, because the previous calibration is not saved in the device memory. To get the most accurate results, we recommend to do calibration with the same cuvette using the same orientation which will be used for measurement. Calibration should be performed with distilled water or with cultivation medium. To check if calibration was done well, measure OD680 and OD720 of the calibration liquid (distilled water or medium). The result should be max 0,0003. If it is higher, perform the calibration again.

  • How is defined optical density in the AquaPen-C?
  • It is defined as OD = -Log(I/Io) where Io is the irradiance that is transmitted through the cuvette filled with medium without algae or other organisms. This quantity must be measured as the reference. I is the irradiance transmitted through the cuvette with algal or cyanobacterial suspension in which OD is measured. Log is the decadic logarithm of the I/Io ratio. Thus, optical density OD = 1 means that light at the respective wavelength is attenuated by algae or cyanos 10 times relative to the reference. With OD = 2, the attenuation relative to the reference is 100 times.

  • Can I measure chlorophyll concentration in the AquaPen-C, and at which range?
  • In the AquaPen-C, chlorophyll concentration is based on optical density measurements at 680 nm. It is an indirect method of chlorophyll concentration measurement. For accurate determination of chlorophyll content in your samples we recommend to perform your own calibration curve between OD 680 nm and chlorophyll content based on chlorophyll extraction. As this dependence largely differs across species and cultivation conditions.
    Minimal chlorophyll concentration which you can measure with this device corresponds to 0.5 µg chlorophyll/L. The upper limit is defined by the principle of OD measurement and the fact that values over OD 680 nm 1 are influenced by large error of measurement.

  • Is it possible to measure only Chlorophyll A with the AquaPen-C?
  • The AquaPen measures Chlorophyll A and Chlorophyll B together. Excitation lights are 455 nm and 620 nm, emission band is 660-750 nm.

    Monitoring Pen

  • What is the purpose of the PAR sensor (Light Meter) ?
  • Integrated Light Meter serves for direct digital readouts of Photosynthetically Active Radiation (PAR) in the range from 400 to 700 nm, the span in which plants use energy during photosynthesis. PAR is measured as Photosynthetic Photon Flux Density (PPFD), which is indicated by units of quanta (photons) per unit time per unit surface area. The sensor has a uniform response to photons within the 400 - 700 nm waveband.


  • Is there correlation or conversion between SPAD and NDVI index that is measured in the PlantPen NDVI-310?
  • There is strong correlation between SPAD and NDVI index, yet no direct conversion is possible. But both measurements refer to the same physiological information about the plants.

  • What is expected number range for PRI measurements in the PlantPen device?
  • The range of PRI is -1 to +1.

  • What is meaning of functions A and B, which appear in the measuring process in the PlantPen?
  • It means the reflectance values at 531 nm and 570 nm from which the PRI parameter is calculated (PRI = (R531-R570)/(R531+570)), A = R531 nm; B = R570.

  • What is meaning of functions: Multiplication and Average in the PlantPen Setting Menu?
  • Multiplication is for obtaining the multiplied results. Multiplication could be x10, x100, x1000. It means, the result is PRI = 0.0523 when multiplication is set 1x, PRI = 0.523 when 10x, PRI = 5.23 when 100x and PRI = 52.3 when 1000x. Average measures the sample defined times (eg. 25x) and makes the average values from these 25 measurements. Higher the average value, then longer is the measuring time (but still it is couple of seconds). It could be useful for getting more precise results.


  • Are nitrogen values measured and displayed in % in N-PenN 110 given in absolute or relative values?
  • N-Pen measures nitrogen content in plant dry matter (in %) and predicts protein content in grains (in %). The measurements are precise if second youngest leaves are measured at mid-tillering.

  • I understand that the N-PenN 110 device does not provide formulas of relative nutrition state for each growth stage and corresponding nitrogen nutrition recommendations. But can you at least provide with a prediction of nutrition state?
  • Yes,simplified predictions are: (1) Green NDVI higher than 0.65 indicates 100% nitrogen nutrition state (N=100%); (2) Green NDVI lower than 0.25 indicates 0 % nitrogen (N=0%); (3) If Green NDVI value is in between 0.25 and 0.65, then nutrition state is calculated as N (%) = (green NDVI – 0.25) * 250. The nutrition state in younger plants during tillering should be generally higher than in later stages with emerged flag leaf.

  • Can N-PenN 110 be calibrated to measure nitrogen values in other plants than barley, wheat and maize?
  • Theoretically, the N-Pen can be calibrated for any plant species. In N-Pen leaf reflectance is correlated with nitrogen content that is determined by chemical analysis. Calibration procedure must include measuring optical signal with the N-Pen and analysis of chemically measured leaves for N content (standard AAS). Enough repetition is needed for statistical analysis; finding appropriate time and conditions for measurements during the plant growing season is also important.

    PolyPen RP 410

  • In the PolyPen RP 410, besides the different indices we get different Excel spreadsheets with: Spectrum / Spectrum Scope / Spectrum Absorbance / Spectrum Transmittance. But no reflectance?
  • Export options in the software are related to calculation not the physical measurement setup. We are using the same software for multiple SpectraPen versions and thus not all options may be active in the PolyPen. Here are short descriptions of the export options: Spectrum - raw data with separate dark and reference spectra; Scope - scope data with dark subtraction (not in PolyPen); Transmitance - transmitance = I/Iref; Absorbance - absorbance = log Iref/I. Reflectance is calculated the same way as transmittance (it is not measured through a leaf).

  • Is it possible to measure transmittance and absorbance with the PolyPen RP 410?
  • Polypen measures reflectance. Transmittance/absorbance is calculated from reflectance as T = I/I0, where T = transmittance, I = measured light intensity, I0 = reference light intensity, basically it is the reflectance corrected to white calibration standard. White calibration is done by inserting the Spectralon under the leaf clip.

  • Is the reflectance standard used in the PolyPen RP 410 calibrated?
  • No, it is not calibrated but the error is less then 2%.

  • How can I clean the reflectance standard used in the PolyPen RP 410?
  • Please see the video or check instructions.

  • What is the maximum reading number we can measure with PolyPen RP 410?
  • Maximum raw value is 65535.

  • What is lifetime of the LED used in the PolyPen RP 410?
  • LED lifetime depends on the frequency of usage. Under normal conditions it exceeds 5 years.

  • How can I program my own index in the PolyPen RP 410?
  • If you want to calculate your own index, you can of course do it from the raw data in Excel or you can add this formula to the Config/Formulas.txt in the PolyPen program folder. Syntax is very simple, for example: Transmitance:CRI2:Caroteniod Reflectance Index 2:1/Transmitance[510nm]-1/Transmitance[700nm]. Each parameter is separated with colon: the first one is data set which will be used as source data (leave there Transmitance); the second is name; the third is description and the last one is calculated formula. After you edit the Formulas file, restart the SpectraPen software. Your index should appear in the list and also in the exported data.

    SpectraPen SP 110

    SpectraPen mini

  • What's the number of spectral points and the bandwidth between two wavelengths?
  • There are 288 pixels in the sensor (CMOS). The guarantied maximal value of the resolution is 15nm for all sensors. Actually, the sensors we use in production have typically about 10nm spectral resolution (according to their calibration lists). Please note that wavelengths are not equidistantly spread, so in general, the bandwidth between two wavelengths differs (is nonlinear) and is lower than the maximal value. Measured spectrum can be then interpolated to different values (also linear space).

  • Which Android version is needed for connection with the SpectraPen mini?
  • The application requires Android 5.0 or higher.

  • How are the measured data transferred from the SpectraPen mini to Android?
  • The data are transferred via Bluetooth Low Energy protocol.

  • Can I also connect the SpectraPen mini to a tablet?
  • Yes, this is also possible.

  • Is there any tutorial video available for the SpectraPen mini?
  • Yes, you may find it here.

  • How are single measurements stored for later data processing?
  • Measurements may be exported in a proprietary binary file *.spec and shared via an e-mail or other applications (Google Drive, Messenger, Viber etc.). The file may be opened in a PC software SpectraPen SW and measured data may be exported to CSV file.

  • Is there a cosine corrector in the SpectraPen mini?
  • Yes, there is a teflon cosine corrector.

    SpectraPen LM 510

  • What is maximum light intensity that can be measured by the SpectraPen LM 510 light meter?
  • Intensity up to 5,000 umol/m2/s can be measured.

  • Does the SpectraPen LM 510 use a CCD-chip or Prisms monochromator?
  • It uses a Polychromator with CMOS linear image sensor.

  • In SpectraPen LM 510 , what is the average light sensitivity per channel?
  • The integration time of the sensor is automatically adjusted between 5ms up to 10s to accurately measure the light intensity between 1 umol m−2s−1 up to approx. 5000 umol m−2s−1.

  • Can SpectraPen LM 510 measure the intensity of light individually for pre-selected parts of spectrum?
  • Yes, one pre-selected part of spectrum can be measured at one time.


  • Can I measure Leaf Area Index in smaller plants?
  • Yes, on condition that the sensor is placed under the canopy, typically directly above the ground surface.

  • What is the difference in between the LAI-2000 and LaiPen LP 110?
  • LAI-2000 measures the attenuation of diffuse sky radiation at five zenith angles simultaneously, it has five detectors. The correct way of measurement is conditioned by attaching an appropriate view cup to hide foreign objects in the field of view. Our LaiPen is designed to avoid the system of view restrictor cups. This means it has a single view cup and a single detector and the four subsequent angles must be measured separately with the help of build-in electronic inclinometer and visual-acoustic indicator. In LaiPen, the permanent restricting cup has restriction angle 160 along x axis and 1120 along y axis, which is different from LICOR LAI 2000.

  • Can I correct measurements for clumping effects in the LaiPen LP 110?
  • The only measurement you do with LaiPen is irradiance. In this respect, you can not correct measured irradiance values for clumping during measurement, but you can correct your calculation of LAI index afer you download irradiance values from LaiPen to computer.

  • What is the exact geometry/configuration of the ring sensors in the LaiPen LP 110?
  • There are no ring sensors in LaiPen. Instead, the LaiPen device is equipped with a single wide-angle optical sensor used in conjunction with a cup restricting 160 / 1120 angle sector. All angles (in multiple angle measurement mode) are measured only with one sensor. The other four angles are obtained by subsequent inclinations of the device from zenith angle, which is controlled by electronic inclinometer with pre-defined five angle positions.

  • Can I exclude specific rings from the LaiPen LP 110 computation, or change path lengths of different rings (not homogeneous canopy) or measure single trees?
  • In multiple-angle measurement mode you always measure all five angles. But since the data you download from the LaiPen to computer for further processing are only uncomputed raw values, exclusion of any measurement would be possible. It is not possible to change the path lengths - these are fixed. And the single trees measurement, for sure it can be done.

  • The website claims we can measure under different sky conditions with the LaiPen LP 110, but the way the instrument deals with this is unclear?
  • The dual sensor mode of measurement alows to estimate reference values for each particular time of measurement in changing weather conditions much more efficiently than the single sensor mode. The way how single sensor mode of measurement deals with this issue is decribed in the first version of Lai Pen manual (chapter 7.A. Single Sensor Mode of Measurement). The computation in case of dual sensor mode of measurement is described in the second attached file named: “Dual mode_ Introduction.pdf”, which is not included in the first version of manual.