A method for synchronous measurement of illuminance and luminance using multiple probes

      Illuminance colorimeters are typically used to collect the illuminance, color temperature, and chromaticity coordinates of light sources (such as office LEDs), while luminance colorimeters are typically used to measure the luminance, chromaticity coordinates, and color temperature of displays (LCD/LED/OLED).

      A single instrument can usually only collect photometric data from one location, and synchronously collecting photometric data from multiple locations is often a tricky task that requires users to develop or customize specialized software systems, with long cycles and high costs.

      For example, a car light source room requires real-time monitoring of the illuminance at various spatial locations, and outdoor large LED advertising screens require simultaneous testing of luminance data at multiple points on the screen. Such application scenarios are relatively complex. The author introduces a simple and cost-effective multi probe illuminance and luminance synchronization testing method, which uses free HMST synchronization testing software and multiple illuminance/luminance  colorimeters.

I  Overview of CL300/CI300 Instruments (High Cost Performance)

      The CL300 illuminance colorimeter adopts CIEXYZ filter & CMOS sensor for light signal acquisition, which can measure indicators such as light source illumination, color temperature, chromaticity coordinates, dominant wavelength, color tolerance, blackbody deviation, color purity, etc. The measurement range can reach up to 200000 lx. The instrument has conventional measurement mode, continuous measurement mode, and high-speed measurement mode (3 milliseconds/time). The instrument is equipped with professional computer software HIQC and can also be connected to a mobile app. The instrument is designed as a probe and can be connected to other devices via Bluetooth, TypeC USB, or serial port, making it ideal as an optical module embedded in automation equipment.

      The CI300 color analyzer adopts CIEXYZ filter & CMOS sensor for light signal acquisition, which can measure indicators such as luminance, color temperature, chromaticity coordinates, color gamut, color tolerance, and color purity of the light source (display). The measurement range can reach up to 200000 cd/㎡. The instrument has conventional measurement mode, continuous measurement mode, and high-speed measurement mode (3 milliseconds/time). The instrument is equipped with professional computer software HIQC and can also be connected to a mobile app. The instrument is designed as a probe and can be connected to other devices via Bluetooth, TypeC USB, or serial port, making it ideal as an optical module embedded in automation equipment.

      The instrument supports secondary calibration using HCAL software and can communicate with industrial control computers through USB interface or Bluetooth (customizable WIFI). It adopts the standard Modbus communication protocol and has multiple development platform example demos, making secondary development very easy to learn.

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II  Overview of CL700/CI810 Instrument (High Accuracy)

      The CL700 spectrophotometer uses a high-precision concave grating as the spectral component, which can collect the radiation spectrum of the light source in the wavelength range of 360-780nm and output a 1nm interval irradiance spectrum. The measurement range can reach up to 200000 lx. The instrument can not only measure irradiance spectrum, illuminance, color temperature, color rendering index, white balance and other technical parameters; It can also measure plant growth lamp parameters, display color gamut, uniformity CQS,TM-30,Parameters such as transmittance and luminous intensity. The instrument is equipped with a 2.8-inch TFT capacitive touch screen, 3000mAh lithium-ion battery, Bluetooth/WIFI multifunctional chip, and large capacity storage.

      The CI810 spectral color analyzer uses high-precision concave gratings as spectral components, which can collect the radiance spectra of light sources in the wavelength range of 360-780nm, output radiance spectra at 1nm intervals, measure at 1 ° angle, with a minimum measurement area of Φ 22mm, and a measurement range of up to 200000 cd/㎡. The instrument can not only measure technical parameters such as radiance spectrum, luminance, color temperature, color rendering index, chromaticity coordinates, dominant wavelength, peak wavelength, etc; It can also measure parameters such as display color gamut, uniformity of light-emitting panels, CQS, TM-30, etc. The instrument is equipped with a 2.8-inch TFT capacitive touch screen, 3000mAh lithium-ion battery, Bluetooth/WIFI multifunctional chip, and large capacity storage.

      The instrument can communicate with the industrial control computer through USB interface or Bluetooth (customizable WIFI), using the standard Modbus communication protocol. There are multiple development platform example demos, making secondary development very easy to get started with.

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III HMST Multi device synchronous test software

        The HMST color synchronous measurement software system is a synchronous measurement software for illuminance/luminance colorimeters running on the Windows operating system. The software supports connection testing of CL700/CL300 and CI810/CI300 colorimeters.

The instrument can be connected to HMST software via USB interface (multiple instruments can use USB HUB) or Bluetooth, which supports up to 255 instrument connections for synchronous testing.

        Note 1: HMST supports Win10/Win11 and above operating systems

        Note 2: HMST supports exporting test data as Excel spreadsheet data

        Note 3: HUICOROR's various models of illuminance/luminance  colorimeters support secondary development. Users with secondary development needs can contact customer service to provide development SDKs and demos.

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IV Design proposal and instructions for use

       4.1 High cost-effective solution for using CL300/CI300 instruments

       The CL300/CI300 instrument adopts CIE XYZ+CMOS detector to achieve photometric data acquisition, and the testing accuracy can meet the requirements of conventional accuracy. The probe design is compact in size and cheap in price.

       For application scenarios that require high precision, HCAL calibration software can be used to perform secondary calibration on CL300/CI300 instruments, ensuring high testing accuracy even when testing specific samples.

       Please refer to section 4.2 for specific usage instructions

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        4.2 High precision testing plan using CL700/CI810 instrument

        The CL700/CI810 instrument uses grating spectroscopy to achieve photometric data acquisition, which can output spectral data at 1nm intervals. The testing accuracy is very high and can meet the requirements of high precision. The CL700 probe can be separated from the host, and the instrument cost is slightly higher.

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        The usage method is as follows:

        ① Prepare multiple CL700/CI810 instruments, USB HUB (required when there are few USB ports on PC computers), and PC computers;

        ② Download the free HMST software from the HUICLOR official website and install it correctly on your PC according to the README instructions;

        ③ The instrument is connected to a PC computer via USB or Bluetooth (Windows 10 and above operating systems do not require driver installation);

        ④ As shown in Figure 7, open the HMST software, click the refresh button, and the software will automatically refresh the USB interface. Then click connect again, and the instrument and HMST software will be successfully connected;

        ⑤ As shown in Figure 8, clicking on 'Measure' will initiate the synchronization of test data by the connected instrument and upload it to the HMST software;

        ⑥ As shown in Figure 9, click Export to Excel to export the HMST software data in Excel format.

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V Test examples and data export

        As shown in Figures 10-12, the author used two CI810s and two CL700s connected to HMST software to synchronously measure office lighting LEDs. The software is smooth to use and can export various chromaticity data.

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