GB225690A - Apparatus for photometric measurements and comparisons - Google Patents

Apparatus for photometric measurements and comparisons

Info

Publication number
GB225690A
GB225690A GB2813823A GB2813823A GB225690A GB 225690 A GB225690 A GB 225690A GB 2813823 A GB2813823 A GB 2813823A GB 2813823 A GB2813823 A GB 2813823A GB 225690 A GB225690 A GB 225690A
Authority
GB
United Kingdom
Prior art keywords
patch
luminosities
luminosity
lens
aperture
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB2813823A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to GB2813823A priority Critical patent/GB225690A/en
Publication of GB225690A publication Critical patent/GB225690A/en
Expired legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J1/00—Photometry, e.g. photographic exposure meter
    • G01J1/10—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void
    • G01J1/20—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle
    • G01J1/22—Photometry, e.g. photographic exposure meter by comparison with reference light or electric value provisionally void intensity of the measured or reference value being varied to equalise their effects at the detectors, e.g. by varying incidence angle using a variable element in the light-path, e.g. filter, polarising means

Abstract

225,690. Waldram, J. M. Nov. 8, 1923. Comparison photometers are constructed so that one of the luminosities to be compared is seen as a background of graduated brightness from one edge to the other, while the other luminosity appears as two uniformly illuminated patches within the background, Fig. 4. The values of the two luminosities are varied relatively until the part of the background surrounding one patch appears brighter than the patch, and the part of the background surrounding the other patch appears darker than this patch. Light from one source is reflected into the apparatus by a mirror 0 through a lens A, the aperture being controlled by an iris diaphragm B operated by a ring C. This light is received on a ground glass screen D which is viewed through an eyepiece F by means of an inclined silvered mirror E, the centre of which is set off the axis of the lens A to give a field view of graduated luminosity. Parts of the silvering of the mirror E are removed for the observation of the other luminosity viewed through the aperture G. Filters H, J are adapted to be inserted in the paths of the rays when the luminosities are widely different, and are actuated by a knob moving a slide K; movement in one direction placing the filter J in position, and movement in the other direction placing the filter H in position. An extension of the slide K carries a cylindrical scale plate M upon which three scales are engraved, calibrated for each position of the slide K. The scales are at right-angles to the axis of the lens and are observed through an aperture N in the ring C controlling the iris diaphragm.
GB2813823A 1923-11-08 1923-11-08 Apparatus for photometric measurements and comparisons Expired GB225690A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB2813823A GB225690A (en) 1923-11-08 1923-11-08 Apparatus for photometric measurements and comparisons

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2813823A GB225690A (en) 1923-11-08 1923-11-08 Apparatus for photometric measurements and comparisons

Publications (1)

Publication Number Publication Date
GB225690A true GB225690A (en) 1924-12-11

Family

ID=10270843

Family Applications (1)

Application Number Title Priority Date Filing Date
GB2813823A Expired GB225690A (en) 1923-11-08 1923-11-08 Apparatus for photometric measurements and comparisons

Country Status (1)

Country Link
GB (1) GB225690A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2921497A (en) * 1954-03-25 1960-01-19 Mine Safety Appliances Co Optical instrument for smoke determination

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2921497A (en) * 1954-03-25 1960-01-19 Mine Safety Appliances Co Optical instrument for smoke determination

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