EMVA 1288 measurements made
- simpler
- faster
- more flexible
- more affordable
with the compact ACC4
for C and S mount cameras.
Test equipment AEON Camera Calibrator (ACC)
Accurate measurements according to EMVA 1288 - easy and affordable
AEON offers customizable test equipment in two sizes, one for standard sensors and the other for sensors with diagonals up to 80 mm. Both are modular and complete turn-key systems with customizable LED light sources and all required evaluation software based on AEON's powerful heurisko® image processing software running on Microsoft Windows. A heurisko® Developer license is included.
The whole set of measurements is conducted automatically after measurement configuration. Following completion of measurements, a datasheet can be generated automatically. Batch processing and integration into other software environments are possible.
Key features
| Model | ACC2 | ACC4 |
|---|---|---|
| Largest sensor diameter | 80 mm | 18 mm (1.1“ sensor) |
| Standard camera adaptors | S, CS, C, Nikon F Others on request |
S, CS, C |
| Light source | Pulsed or current controlled LEDs 4 or 8 colors, two intensity levels or 14 colors, one intensity level Ø 84 mm, Exchangeable |
Pulsed or current controlled LEDs 4 colors, one intensity level Ø 21 mm Not exchangeable |
| Special design on request (e.g. HDR module: one color with three intensity levels). |
Special design on request. | |
| Wavelengths | Examples for standard configurations 4-color model: 470, 530, 625, 850 nm 8-color model: 365, 405, 470, 530, 625, 725, 850, 940 nm 14-color model: 405, 415, 425, 460, 480, 500, 530, 590, 610, 625, 660, 690, 725, 750 nm Other wavelength combinations on request (range 265 - 1550 nm, white). |
Examples for standard configurations VIS-NIR: 470, 520, 630, 850 nm SWIR: 1050, 1200, 1300, 1550 nm Other wavelength combinations on request (range 265 - 1550 nm, white). |
| Calibration | Split optical path with built-in calibrated photo diode. | Split optical path with built-in calibrated photo diode. |
| For increased dynamic range measurements | M82 thread for neutral filter | Tray for easy insertion of neutral or polarization filters |
| Overall dimensions (L x W x H) | 900 x 130 x 140 mm | 297 x 79 x 70 mm |
| Control interface | USB 2.0 | USB 2.0 |
| External power supply | DC voltage up to 48 VDC depending on model and design | None (5 VDC, 450 mA via USB) |
Measurements
The ACC systems conduct all measurements required by the newest release of the EMVA 1288 standard.
The systems do not measure temperature dependency of the dark current and spectral dependency of the quantum efficiency. These measurements are optional because they require special equipment that would increase the effort considerably.
Linearity, noise, and sensitivity
According to the standard, these measurements are usually performed with monochromatic green light for monochrome cameras and with blue, red, and green light for color cameras at 50 irradiances at least and at darkness. If the camera features at other wavelengths are of interest, an ACC can also be equipped with these colors.
Spatial non-uniformities
With only a few illumination steps, mean and variance of each individual pixel are computed by averaging at least 100 images. With these data it is possible to analyze the spatial non-uniformities of the dark image and of the sensitivity of the sensor.
Dark current
The dark current is determined by taking many images at different exposure times without any illumination.
Derived quantities and data sheet
From these measurements, the following parameters are derived:
- Absolute gain factor
- Absolute sensitivity threshold and saturation capacity
- Maximal signal-to-noise ratio
- Dark noise
- Dynamic range
- Non-linearity
- Spatial inhomogeneity of the dark image (dark signal non-uniformity, DSNU) and of the sensitivity (photoresponse non-uniformity, PRNU)
- Quantum efficiency at the wavelengths of the ACC light source
Measurement results are provided as diagrams in PDF format and as tables in CSV format. Images of the DSNU and PRNU are provided in PNG format. All essential intermediate results are stored for repeated evaluation. Data can be used to automatically generate a data sheet complying with the standard.
Hardware
The ACC is a modular optical system, which is described in more detail in the following. Please refer also to the table above.
The optical system consists of a tube system with interchangeable optical components including a homogeneous light source and a standard camera mount such as Nikon F mount, C mount or M72. (From the camera's point of view, the ACC mount looks like a lens mount.) The length of the tube is determined by the diameter of the light source, as determined by the standard. The system is light-proof; no need for dim-out of light.
All light sources are current-controlled LEDs. Current is controlled digitally with 12-bit resolution. The irradiation of the image sensor can be varied either by changing the LED current at constant exposure time or by changing the exposure time of the camera at constant LED current or by using the pulse mode of the light source. The first two methods make measurements simple because it is not necessary to trigger the camera or the light source. The camera just needs to be connected to the computer for grabbing images.
The whole system is controlled by a computer via a single USB connection.
Camera interfaces
- GigE Vision and USB3 Vision
- All cameras of Imaging Development Systems (IDS) via IDS’ peak
- All cameras of Basler via Basler’s pylon
- Camera Link, Camera Link HS, CoXPress
- and GigE Vision via Basler's frame grabbers
- Camera Link via Teledyne Dalsa’s Sapera LT
- CoaXPress via Euresys’ Coaxlink
- Cameras of PCO
Support of further interfaces and SDKs can easily be added in the form of a DLL by use of the ACC software generic interface for data acquisition. Some interfaces may be easily supported by adding just a few code lines in a heurisko script. Please contact us for discussion of your requirements.
Customization to meet specific requirements are possible. For example, an ACC4 was modified in order to mount it to a climate chamber. The electronics is located outside the chamber in an environment with normal ambient temperature while the camera is located inside the chamber (see picture).
