What Types of Cameras Are Used in Machine Vision?
- Primary Camera Types and Technologies
A. Area Scan Cameras
Function: Capture 2D images in a single frame, ideal for static or slow-moving objects.
Key Specifications:
Resolution: 0.3 MP (VGA) to 150 MP (e.g., semiconductor wafer inspection).
Frame Rate: 30–200 FPS (standard), up to 1,000 FPS for high-speed models.
Sensor Type:
CMOS: Dominates 90% of industrial applications due to low cost, high speed, and rolling/global shutter options.
CCD: Preferred for low-noise imaging in astronomy or medical microscopy (dynamic range >75 dB).
Applications: Barcode reading, surface defect detection, and dimensional metrology.
B. Line Scan Cameras
Function: Capture images line-by-line for continuous motion (e.g., web inspection).
Key Specifications:
Line Rates: 1–140 kHz (e.g., 4k-pixel lines at 70 kHz for printing defect detection).
Pixel Width: 5–10 μm for high-density imaging.
Applications: Textile, metal strip, and print quality inspection.
C. 3D Cameras
Technologies:
Stereo Vision: Dual cameras for depth mapping (accuracy ±0.1 mm).
Structured Light: Projects patterns to measure object topography.
Time-of-Flight (ToF): Measures light travel time for real-time 3D mapping (e.g., bin picking).
Applications: Robotics guidance, weld seam inspection, and volume measurement.
D. Specialty Cameras
SWIR (Short-Wave Infrared): 900–1700 nm range for material penetration (e.g., solar cell inspection).
Thermal Cameras: Detect heat signatures (accuracy ±1°C) for electrical fault detection.
UV Cameras: 200–400 nm sensitivity for fluorescence or semiconductor lithography. - Critical Selection Criteria
A. Resolution and Pixel Size
Rule of Thumb: Minimum resolution = (Feature Size ÷ Pixel Size)².
Example: Detecting 0.1 mm defects requires 2 MP (1600×1200) with 5 μm pixels.
B. Frame Rate and Shutter Type
Global Shutter: Freezes fast motion without distortion (e.g., 500 FPS for bottling lines).
Rolling Shutter: Cost-effective for static or slow-moving objects.
C. Spectral Sensitivity
Monochrome vs. Color:
Monochrome: Higher sensitivity (2–4×) for low-light or laser-based systems.
Color: Essential for food grading or pharmaceutical blister pack inspection.
D. Interface Standards
GigE Vision: Up to 10 Gbps; cable lengths up to 100 m.
USB3 Vision: 5 Gbps; plug-and-play for portable systems.
CoaXPress: 12.5 Gbps/channel; long-distance data transmission.
E. Environmental Durability
IP Ratings: IP67 for washdown environments (food processing).
Temperature Range: -40°C to +70°C operation for automotive testing. - Industry-Specific Applications
A. Automotive Manufacturing
Camera Type: 5 MP global shutter CMOS with GigE interface.
Tasks:
Inspect engine components for cracks (10 μm resolution).
Verify brake pad alignment (±0.05 mm accuracy).
B. Electronics Production
Camera Type: 25 MP area scan with 3.2 μm pixel size.
Tasks:
Solder joint inspection on high-density PCBs.
OLED display uniformity testing.
C. Pharmaceutical Packaging
Camera Type: 2 MP color camera with coaxial LED illumination.
Tasks:
Verify pill count and blister seal integrity.
Detect label misprints (Pantone color matching).
D. Agriculture and Food Processing
Camera Type: 3D ToF cameras with IP69K housing.
Tasks:
Sort fruits by size and ripeness (RGB + NIR).
Detect foreign objects in packaged goods. - Emerging Trends
Embedded Vision: Cameras with onboard AI processors (e.g., NVIDIA Jetson) for defect classification.
Multi-Spectral Imaging: 6–8 channel cameras for hyperspectral material analysis.
Quantum Dot Sensors: Enhanced UV/IR sensitivity for semiconductor inspection. - Comparison of Leading Camera Brands
Brand Specialty Key Model Resolution Frame Rate
Basler High-speed ace 2 Pro 20 MP 163 FPS
FLIR Thermal imaging A700 640×512 30 Hz
Teledyne Line scan Linea HS 8k pixels 140 kHz
Sony Global shutter IMX540 12 MP 40 FPS
