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Instrument

Photometer

Physical Sciences
Photometer glyph

A photometer is an instrument for measuring photometric quantities such as luminous flux, illuminance or luminance, widely used in astronomy and lighting science.

Facts
Open Questions
Resolution
Not stated as a numeric figure in the cited source. 1
The cited source gives no numeric sensitivity or resolution figures for photometers generally; it describes visual comparison and photon-counting methods without stating detection thresholds.
Operating Range
Not stated as a numeric figure in the cited source. 1
The cited source gives no numeric light-intensity range for photometers generally, only historical method descriptions and a detector time-resolution figure unrelated to intensity range.
Invented Year
1729 2
Measures
Luminous flux, illuminance or luminance. 1
Operating Principle
Detects light by converting it into an electric current using a photoresistor, photodiode or photomultiplier; several rival mechanical and electrical designs were already in common use by the 1860s. 1
Classification
Instrument Class
Measurement or Metrology Instrument 1
Connections

Belongs To Instrument Class

Instrumentation, Concepts

Invented By

Benjamin Thompson, Count Rumford, Scientists

One of several early photometer designs in common use by 1861, alongside Ritchie's photometer and shadow extinction methods; no single fixed invention year is established for the instrument class.

Source Photometer (Wikipedia)

Open Questions

When was the photometer invented, and by whom?, Open Questions
Source Photometer (Wikipedia)

Used In

Astronomy, Disciplines
Source Photometer (Wikipedia)
Chemistry, Disciplines

The photometer is a principal instrument in analytical chemistry.

Source Photometer (Wikipedia)
Sources
1. Photometer (Wikipedia)
Wikipedia
  • Lead section
    A photometer is an instrument for measuring photometric quantities such as luminous flux, illuminance, or luminance.
  • Overview section
    Most photometers detect the light with photoresistors, photodiodes or photomultipliers.
  • History section
  • Photon counting section
  • Lede, instrument class
    A photometer is an instrument for measuring photometric quantities such as luminous flux, illuminance or luminance, widely used in astronomy and lighting science.
  • Invented By: Benjamin Thompson, Count Rumford
  • Used In: Chemistry, Applications section
    The photometer has become one of the principal instruments in biochemistry and analytical chemistry.
View the Source
2. Wikipedia: Pierre Bouguer
WikipediaCareer section
Quote, Career section
In 1729 he published Essai d'optique sur la gradation de la lumiere, the object of which is to define the quantity of light lost by passing through a given extent of the atmosphere, and became the first known discoverer of what is now more commonly known as the Beer-Lambert law.
View the Source
Open Questions (1 open question)
When was the photometer invented, and by whom?

Wikipedia's Photometer article states three photometer types (Rumford's, Ritchie's, and shadow-extinction types) were already in common use by 1861, but names no invention year or event for the instrument itself. The existing invented edge already credits Benjamin Thompson (Count Rumford), but neither his own Wikipedia biography nor the Photometer or Photometry (optics) articles state a year. A web search found a plausible date, Rumford's 1794 paper in Philosophical Transactions vol. 84, but the corroborating page (Citizendium) returned HTTP 403 and was not visited, so it is not citable under the quote-capture duty.

What would resolve this A fetchable, quotable page (not blocked) that states the year Rumford, Ritchie or an earlier figure such as Bouguer or Lambert first built or described a working photometer, ideally naming the specific publication (Rumford's 1794 Philosophical Transactions paper is the leading candidate).
History of sciencePhotometer (Wikipedia)

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