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Goniometric (spectral)

Goniometric (photometric)


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The Murakami Team
Murakami Products
Avian Technologies LLC
Murakami Corporate


Spectrophotometric Transmittance Meter

This instrument is designed for measuring diffuse transmittance, equipped with an integrating sphere for the source of diffuse illumination. The double-beam design provides precise and stable measurements, especially for transmittance measurement of specimens which are transparent or translucent. The geometry is also suitable for non-flat samples, such as concave or convex glass, and lenses. The horizontal specimen table allows fast, easy placement of samples, and makes much more efficient use of your operator's time. The DOT-3C can measure very thick samples (max 30mm), making it ideal for the measurement of the transmitted color for the lenses of spectacles.

The DOT-3C is well-suited to make measurements of a wide variety of solid and liquid applications including:

  • Determining the color of lenses
  • Transmittance of glass and plastics
  • Transmittance of filters
  • Transmittance of liquids, including beer, wine, whiskey, juices, and edible oils.

Operational Information

The light from the halogen lamp passes through an infrared filter before entering the integrating sphere. This is to reduce any effect due to warming of the sample. After being integrated in the sphere, the diffuse light illuminates the sample, and the transmitted light (sample beam) is directed to the chopper mirror.
     A second sphere port allows the reference beam to exit the sphere without passing through the sample. This beam is also directed to the chopper mirror.
     The chopper mirror alternately allows either the sample beam or the reference beam to enter the polychromator. Each beam in turn is dispersed by the concave grating and imaged onto the detector array.
     The shutter at the polychromator entrance is used for measuring the dark current of the detector array.
     Last, a processing step uses the signals for sample beam, reference beam, and dark current to calculate the spectral transmittance of the sample.


Measuring MethodDouble-beam spectrophotometer
Measuring GeometryDiffuse illumination, normal viewing (d:0°)
Sphere Diameter150mm
Viewing Area4mm x 8mm
Illumination Area40mm diameter
Sample ThicknessMaximum 30mm
Spectral Range390nm - 730nm
Wavelength Interval10nm
Spectral BandpassApproximately 10nm
Dispersion System Concave diffraction grating
Light SourceHalogen lamp, 12V, 50W
Detector35 element silicon photodiode array
A/D converter16 bits
Computer interfaceRS-232
Data transfer timeabout 4 seconds - variable (1.5 seconds when delivered)
Reproducibility0.03% max standard deviation, 30 measurements of air when data transfer time set to 3 sec
Power requirements100, 50/60Hz
Power consumption300W
Dimensions324mm x 500mm x 342mm (W x D x H)
Weightapproximately 18Kg


Power cordInstrument cover
RS-232C cableAccessory Case
Spare LampInstruction manual
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