Chlorophyll Fluorescence Imager

Chlorophyll Fluorescence Imager

I. Product Overview

The Chlorophyll Fluorescence Imaging System is a professional instrument for plant photosynthesis research. Utilizing a high-sensitivity CMOS camera and LED light source control, it enables rapid, non-destructive detection and imaging analysis of chlorophyll fluorescence in plant leaves. The system integrates two core functions: OJIP rapid fluorescence kinetics measurement and PAM modulated fluorescence measurement, enabling comprehensive evaluation of plant photosynthetic system activity, light use efficiency, and responses to environmental stress.

Featuring a modular design with highly integrated hardware and software, the system offers a user-friendly graphical interface supporting bilingual Chinese-English switching. It is widely applicable for research and teaching in plant physiology, ecology, agricultural science, environmental science, and related fields.

II. Technical Specifications

Camera:

Resolution: 1608(H) × 1104(V)

Pixel Size: 9µm × 9µm

★Frame Rate: 100 fps

Pixel Depth: 12 bit

Interface Type: USB 3.0

Lens and Optical Parameters

★Focal Length: 12mm

★Maximum Aperture: F/2.8 (dynamically adjustable)

Horizontal Field of View (HFOV): Approx. 62.11°

Vertical Field of View (VFOV): Approx. 44.83°

Maximum Imaging Range: 50cm × 35cm at standard working distance

Light Source Parameters

Blue Light Wavelength: 450 nm excitation source for fluorescence excitation

Red Light Wavelength: 630 nm photochemical light for PAM measurement

Far-Infrared Light: 730 nm for specific measurement requirements

LED Brightness Range: 1% - 100%, peak intensity up to 1440 µmol/(m²·s)

Measurement Range

1. OJIP Measurement

Measurement Duration: 0.1 - 1.0 seconds, adjustable, recommended 1 second

LED Brightness: 1% - 100%, corresponding to 90-1440 µmol/(m²·s), 5% increments

2. PAM Measurement

Dark Adaptation Time: 0 - 3600 seconds, can be set to 0 to skip

Light Cycle Count: 1 - 100 cycles, number of cycles during light adaptation phase

Monitoring Duration: 10 - 120 seconds/cycle, monitoring time per cycle

Recovery Time: 60 - 600 seconds, dark recovery monitoring duration

Photochemical Light Intensity: 1000 - 30000, red light 630nm LED brightness value

Saturation pulse (Fm): 15%–100%, dark adaptation saturation pulse (450nm blue light)

Saturation pulse (Fm'): 15%–100%, light adaptation saturation pulse (450nm blue light)

Sampling Interval: 0.1 - 10.0 seconds, data acquisition interval

Measurement Accuracy

1. Fluorescence Intensity Measurement

Dynamic Range: 12-bit (0-4095)

Signal-to-Noise Ratio: >100:1

Repeatability: CV < 3%

Linearity: R² > 0.999

Sensitivity: Capable of detecting faint fluorescence signals

2. Parameter Calculation Accuracy

Fv/Fm: ±0.005

ΦPSII: ±0.01

qP/qN: ±0.02

NPQ: ±0.1

PIABS: ±0.05

3. Time Resolution

OJIP Mode: Minimum acquisition interval 10 ms

PAM Mode: Minimum sampling interval 100 ms

Exposure time: Adjustable from 100 ms to 1000 ms

Response time: <1 ms (LED light source)

4. Spatial Resolution

★ Imaging Resolution: 1608 × 1104 pixels

Pixel Size: 9µm × 9µm (sensor)

Actual Spatial Resolution: Approx. 0.3mm/pixel (at 50cm × 35cm field of view)

Field of View: Horizontal 62.11°, Vertical 44.83°

★ Imaging Area: Maximum 50cm × 35cm

III. Function Overview

1. OJIP Rapid Fluorescence Dynamics Analysis

The OJIP measurement mode enables rapid assessment of photosystem II (PSII) activity and light use efficiency in plants. By applying intense light excitation, it records the complete rise kinetics from initial fluorescence (Fo) to maximum fluorescence (Fm) within 1 second.

Measurement Principle:

Under dark-adapted conditions, intense light exposure causes gradual reduction of the PSII reaction center QA from its oxidized state, resulting in a rapid increase in fluorescence intensity. This process reflects the efficiency of the electron transport chain and the quantity/activity of PSII reaction centers.

Information Obtained:

O Point (Fo): Initial fluorescence when all PSII reaction centers are open

Point J: Approx. 2 ms, reflecting electron transfer from QA to QB (calculated)

Point I: Approx. 30 ms, reflecting the reduction state of the PQ pool

Point P (Fm): Maximum fluorescence when all reaction centers are closed

Key Calculated Parameters:

Fundamental Parameters: Fv = Fm - Fo, Fv/Fm (maximum photochemical efficiency)

Specific activity: Mo (initial slope), Area (QA reduction area)

Quantum yield: ΦPo (capture efficiency), ΦEo (electron transfer efficiency), ΦDo (thermal dissipation)

Energy flux: ABS/RC, TRo/RC, ETo/RC, DIo/RC

Performance index: PIABS (comprehensive performance index)

Application Scenarios:

Rapid screening of plant materials

Assessment of environmental stress levels

Monitoring changes in growth status

Comparing effects of different treatments

2. PAM Modulated Fluorescence Measurement

PAM measurement mode employs modulated fluorescence technology to monitor plant photosynthetic activity under varying light conditions. It distinguishes between photochemical and non-photochemical quenching, providing insights into plant photoprotection mechanisms.

Measurement Procedure:

Dark-adaptation phase: Plants fully relax in darkness, restoring all reaction centers to open states

Fo and Fm measurement: Apply measurement light and saturation pulses to determine dark-adapted fluorescence parameters

Light-adaptation phase: Apply photochemical light to simulate natural light conditions

Cyclic monitoring: Periodically apply saturation pulses to measure Fs and Fm'

Dark relaxation phase: Immediately apply far-red light after photochemical light shutdown to determine light-adapted minimum fluorescence (Fo')

Dark recovery detection: Shut down both photochemical and far-red light to monitor fluorescence recovery

Key parameters:

Fv/Fm: Maximum PSII photochemical efficiency (0.78–0.84 in healthy plants)

ΦPSII: Actual PSII photochemical efficiency (light energy utilization under illumination)

qP: Photochemical quenching coefficient (proportion of open reaction centers)

qN: Non-photochemical quenching coefficient (photoprotection capacity)

NPQ: Non-photochemical quenching (degree of heat dissipation)

ETR: Electron transport rate (indicator of photosynthetic rate)

Application Advantages:

Non-destructive measurement, repeatable monitoring

Distinguishes between photochemical and non-photochemical processes

Real-time monitoring of photosynthetic dynamics

Evaluates the efficiency of photoprotection mechanisms

★3. Data Analysis and Visualization