The MRC-100 is a controllable contrast source for the testing of imaging systems in the visible spectrum. The distinguishing feature of this source unit is that both the target contrast and the background luminance are adjustable. This differs from the Optikos VLS-100 where only the foreground (target) luminance is adjustable. The MRC-100 Source operates in conjunction with the I-SITE ™ software package which provides the control and calibration facilities.
The MRC-100 Source is essential in fully characterizing the performance of visual systems, image intensifiers, and visible cameras and imagers. It is modular in design and can be added to existing facilities.
Applications
Used in testing the performance of:
- Visual systems
- Video cameras
- Visible cameras and imagers
- Image intensifiers
Introduction to MRC Testing
Minimum Resolvable Contrast (MRC) testing is the measurement of the Modulation Transfer Function with respect to the contrast of a target. As with MRTD,the MRC curve for a visible imager is the minimum contrast required to resolve a target with a specific spatial frequency.
A visible source for MRC testing differs from a thermal source in that an MRC system must also provide visible background illumination. Without detectable background illumination,the target contrast would remain 100%. This differs from the case of the TTG-100 in which a sufficient background signal is provided by the ambient temperature of the target plate.
Features
- Broadband source spectrum from the visible to the near-infrared
- 106 dynamic range in the background illumination
- Independent control of background illumination and contrast of a target pattern
- Absolute mode features independent control of background and target luminance
- Differential mode features independent control of background luminance and contrast
- Motorized filter wheel provides automatic selection of customer supplied filters
- Motorized target wheel provides automatic target selection
- Accommodates different target pattern orientations including 0,45,and 90 degrees
- Calibrated in photometric luminance
Benefits
- Provides a controllable source of uniform illumination and controlled pattern contrast
- Independently controls the target and background luminance
- Enables objective MRC measurement of visual systems with the software package
- Used in testing a large variety of visible and electro-optical imaging systems ranging from image intensified sights to video cameras
Optional Calibrations
The MRC-100 can be calibrated in one of the following ways:
- Photometric units—applicable when testing systems intended to operate in a similar manner to the human eye (for example,a TV camera)
- Radiometric units—this is a custom calibration option that should be discussed with Optikos engineers
Specifications
Operating Parameters
| Waveband selection | Via filter wheel (user selectable) |
| Target contrast modes | Absolute and differential |
| Target patterns | Via target wheel |
| Target plate size | 50 mm diameter (nominal) |
| Output units | Radiance (W/m2/sr) or luminance (cd/m2) |
| Target units | Contrast (2 equations, radiance or luminance) |
| Lamp type | Tungsten halogen |
| Rated lamp life (avg.) | 4000 hours |
| Lamp power supply | Regulated laboratory grade, linear DC power supply |
Output
| Color temperature | 2856 K ± 50 K |
| Spectrum | VIS to NIR |
| Dynamic range | 106 |
| Background luminance | Up to 350 cd/m2 |
| Nominal contrast ranges | 0% – 100% (H-L)/(H+L) |
| Exit beam illumination cone | F/8 or slower collimators recommended |
| Aperture diameter | 50 mm |
| Aperture uniformity | < 2% variation in luminance |
| Power | 115/230V, 50-60 Hz, 450W |
| Physical | W 560 mm x H 1280 mm x D 920 mm (33 kg) |
Standard Equipment
- Source unit
- Power supply
- Motion control unit
MRC-10 Photometer
Monitors and displays source luminance. The photometer is calibrated in
photometric units to NIST traceable standards.
Optional Equipment
Additional equipment will be necessary to support some of the measurements described. A typical test facility would also include a measurement device and a collimator. Optikos can provide complete test systems to suit most requirements.
The Minimum Resolvable Contrast Source is part of an overall measurement system and only operates in conjunction with other metrology instruments.
Target Sets
The patterns on target plate sets include slits, circular apertures and 4-bar targets. Target plate patterns may be fitted vertically, horizontally or at 45 degrees in the turret wheel. Slits and large 4-bar targets are centered on separate plates. Small 4-bar targets are grouped in:
- Grid Positioned Plates
Target patterns are arranged in an arc across the plate and angled so that as the turret wheel is rotated, the specified pattern is brought into the center of the field of view.
MRC-30 Blank Target
| Type | Set | Dimension |
| Blank | 1 target on 1 plate | – |
MRC-40 Slit Target Set
| Type | Set | Dimension |
| Slit | 8 targets on 8 plates | 20 μm – 400 μm in width |
MRC-50 Circular Target Set
| Type | Set | Dimension |
| Circular | 3 targets on 3 plates | 0.2 mm – 20 mm diameter |
MRC-70 Low Resolution 4-Bar Target Set (Grid)
| Type | Set | Dimension |
| 4-Bar | 9 targets on 7 plates | 1.5 mm – 10 mm in periodicity |
MRC-90 High Resolution 4-Bar Target Set (Grid)
| Type | Set | Dimension |
| 4-Bar | 15 targets on 5 plates | 0.066 mm – 1.2 mm in periodicity |
