What does watt/sq. cm/steradian (at 555 nm) measure?

It measures spectral radiance as radiant power per unit projected area per unit solid angle at the wavelength of 555 nm, which aligns with human visual sensitivity.

Why convert to the blondel unit?

Converting to blondel helps interpret modern measurements in the context of older photometric data and historical standards used before SI units became dominant.

Is the blondel still commonly used today?

No, the blondel is obsolete and mostly found in historical records; modern practice uses SI units such as candela per square metre.

Convert Watt/sq. cm/steradian (at 555 nm) to Blondel - Online Unit Converter

Easily convert luminance from watt per square centimeter per steradian at 555 nm to the historic blondel unit. Useful for comparing modern radiometric data with legacy photometric measurements.

Watt/sq. cm/steradian (at 555 nm)

Blondel

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Watt/sq. cm/steradian (at 555 nm) to Blondel Conversion Table

Watt/sq. cm/steradian (at 555 nm)	Blondel

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Start Value

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Watt/sq. cm/steradian (at 555 nm) to Blondel Conversion Table
Watt/sq. cm/steradian (at 555 nm)	Blondel

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What Is This Tool?

This online converter transforms luminance values measured in watt per square centimeter per steradian at 555 nm into the blondel unit, a historical photometric measure. It facilitates comparison between current radiometric measures aligned with human vision sensitivity and earlier luminance units used in lighting engineering.

How to Use This Tool?

Enter the luminance value in watt per square centimeter per steradian at 555 nm.
Select blondel as the target unit for conversion.
View the converted value instantly to compare or document in historical terms.

Key Features

Converts luminance from watt/sq. cm/steradian (at 555 nm) to blondel seamlessly
Supports legacy photometric unit conversions for historical data analysis
Browser-based and user-friendly interface suitable for researchers and engineers
Aligns with photopic peak wavelength for accurate spectral radiance to luminance translation

Examples

0.5 watt/sq. cm/steradian (at 555 nm) converts to approximately 10728538.912009 blondel
2 watt/sq. cm/steradian (at 555 nm) converts to about 42914155.648036 blondel

Common Use Cases

Analyzing spectral radiance of small-area light sources at the photopic peak for vision studies
Converting radiometric radiance measurements to historic photometric units for archival comparison
Evaluating LED, lamp, or optical system output in optical metrology regarding 555 nm wavelength
Referencing early 20th-century photometric data when reviewing lighting engineering literature

Tips & Best Practices

Ensure measurements are taken specifically at the 555 nm wavelength for valid conversions
Consider the historic context of the blondel when interpreting results
Use calibrated spectral radiance instruments to maintain data reliability
Transition to SI units like candela per square metre for modern photometric reporting

Limitations

Blondel is an obsolete unit rarely utilized today, replaced by the candela per square metre
Conversion accuracy depends on measurements at 555 nm; other wavelengths may yield incorrect results
High precision demands well-calibrated instruments and understanding of unit historical usage

Frequently Asked Questions

What does watt/sq. cm/steradian (at 555 nm) measure?: It measures spectral radiance as radiant power per unit projected area per unit solid angle at the wavelength of 555 nm, which aligns with human visual sensitivity.
Why convert to the blondel unit?: Converting to blondel helps interpret modern measurements in the context of older photometric data and historical standards used before SI units became dominant.
Is the blondel still commonly used today?: No, the blondel is obsolete and mostly found in historical records; modern practice uses SI units such as candela per square metre.

Key Terminology

Watt/sq. cm/steradian (at 555 nm): A radiometric spectral radiance unit measuring radiant power per projected area and solid angle at the 555 nm wavelength, relevant to human vision sensitivity.
Blondel: An outdated photometric luminance unit named after André Blondel, formerly used before the adoption of SI units like candela per square metre.
Photopic peak: The wavelength (555 nm) at which the human eye is most sensitive under well-lit conditions, important for correlating radiometric and photometric quantities.

Quick Knowledge Check

What wavelength is specified in the conversion from watt/sq. cm/steradian to blondel?

550 nm

555 nm

560 nm

Which modern SI unit has replaced the blondel?

Lumen

Candela per square metre

Lux

Why is the blondel unit important for some users today?

It is used in current lighting design

It helps interpret historical photometric data

It measures spectral radiance at any wavelength

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