820 Video Photometer

Light Measurement
  • Measures absolute brightness of any size sample or scene in fL or cd/m2
  • Performs statistical process operations over user-defined regions of interest
  • Automatic Location of all characters and objects in a scene and tested to MIL-P-7788E and SAE AS7788 using Locator Option.

Measure Absolute Brightness

The Model 820 Video Photometer measures the absolute brightness of any size sample or scene and provides quantitative data in fL or cd/m2. The 820 photometer is used to measure the performance of lamps, LEDs, backlit panels, control switches, etc. It also quantifies reflectance, micro pitting, reflective and transmissive haze, and other appearance characteristics.

The 820 photometer generates a 640 x 480-pixel image digitized to 256 gray levels. This offers a light measurement capability equivalent to 307,000 light meters. The lower cost 820 utilizes an interlaced camera and TRICOR's Eyeppearance® software (a Windows compatible PC-based software system) to provide analysis tools used to establish photometric levels for an image.

A user-friendly Windows® interface offers many menu options for analyzing the acquired gray scale image; however, the real potential of Eyeppearance® is realized when a calibration transform file is loaded for the image. The calibration transform translates the relative gray levels into absolute radiometric levels. Pixel radiance levels and histogram distributions are given in photopic units.

Some Typical Applications include
  • Appearance characteristics
  • Cluster appliques
  • Lamps
  • Haze
  • Reflectance
  • Backlit panels
  • Control switches
  • Instrument panels
  • LEDs
  • Micro pitting
  • Transmission
  • Light Meter Applications

Menu options, such as the Enhance option, provide a close coupling of the image data and the histogram distribution. The image is highlighted in green for a given section of the histogram. The user can use the mouse to quickly change the highlighted radiance levels in bandwidth and position on the histogram distribution. Also, false coloring can be applied to the image, allowing the user to readily see those areas below, above, and within the user-specified tolerance band. Quantitative values associated with the highlighted area(s) are then displayed on the PC screen.

Another powerful feature of Eyeppearance® is its ability to define up to 254 regions of interest. Each region of interest may be any region as outlined by the user using the mouse. From this region an active subset can be selected, which establishes a new histogram distribution and limits image analysis to this active region only.

  • 820: CCD Interlaced video photometer with eight user-selectable shutter speeds
Receptor Silicon CCD filtered to closely match the CIE relative photopic luminosity response
Calibration System supplied with one set of calibration curves (one curve for each of the eight shutter speeds at one lens f/stop)
Light Measurement Scales Light meter
  • Absolute: absolute luminance scale (fL or cd/m2)
  • Digital: 8-bit image scale (256 gray levels)
  • Relative: linear scale based on camera shutter speed
Analysis Capabilities (partial listing)
  • Pixel interrogation
  • CCF (Color Correction Factor) to correct system response when measuring colored subjects.
  • Real-time false coloring
  • ROI (Region of Interest) selection
Optical System
  • 820: 35-mm, f/1.7 lens standard (other lenses available)
Field of View
  • 820: 13.5° with standard lens
Focusing Distance
  • 820: 15.2 cm (6 inches) to infinity with standard lens
Target Area
  • Minimum: as small as 1 image pixel
  • 820: [0.051mm (0.002 inch) approx.]
  • Maximum: dependent upon measuring distance and field of view with standard lens
Luminance Units cd/m2 or fL selectable; calibration values in memory automatically converted for user display
Light Measurement Ranges
  • 820: 0.1 fL to infinity; 0.34 cd/m2 to infinity
Accuracy ±4% of measured value (Measuring conditions: subject: standard illuminant A; ambient temperature: 20° to 30° C (68° to 86° F)
Short-term Repeatability ±0.4% (Measuring subject: standard illuminant A)
Resultant Image 640 x 480 x 8 bits resolution (256 gray levels)
Temperature Ranges
  • Operating: 0° to 32° C (32° to 90° F); relative humidity less than 85% at 32° C (90° F)
  • Storage: -20° to 55° C (-4° to 131° F) with no condensation
System Components
  • 820 Interlaced CCD Camera: With shutter control and 35-mm, f/1.7 lens. 4.6 H x 4.6 W x 15.2 L cm(1.8 H x 1.8 W x 6 L inches) 378 g (13-1/2 oz.)
  • Cable: 1.8 m (6 feet) long standard
  • Photopic Filter with one set of calibration curves
  • Tabletop Tripod
  • Image Processing Board
  • Eyeppearance® Software
  • Reference Manual
  • Customer Requirement: Personal Computer: Windows® 98, ME, NT, 2000 with half PCI bus slot available
Histogram Classification
Histogram Classification
Profile Window
Profile Window
Locator Option
Locator Option
Software Specification Window
Software Specification Window
Typical Image
Typical Image

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