Principles of PhotometryPhotometry

Principles of Photometry
Photometry is the measurement of Electromagnetic radiation weighted by the human eye's response. This response changes with wavelength, and to an extent, from person to person. Internationally-agreed standard observer functions are therefore used in order to provide a consistent measurement base for photometry; the two most widely used are the V(λ) function, which applies for photopic vision (typical day-time light levels) and the V'(λ) for scotopic vision (low lighting levels). At intermediate light levels (mesopic or ‘twilight’ levels, such as found on lit roads at night), the CIE system of mesopic photometry is used to provide a smooth transition between these two functions.

In photometry, the word 'luminous' is used to indicate that measurements have been made using a detection system (called a photometer) that has a spectral response similar to that of a human eye. The two principal photometric scales maintained at NPL are of luminous intensity and luminous flux. Setting up appropriate geometries permits calibrations of other quantities, such as luminance from luminous intensity standards. NPL has extensive facilities available for the photometric measurement of both sources and detectors, including photometers, luxmeters, luminance meters and colour temperature meters. Services include the calibration of luminous intensity, illuminance, luminance, luminous flux and correlated colour temperature.
Luminous intensity measures the luminous output from a source ina specific direction into unit solid angle. The candela (one of the SI base units, abbreviation cd), is the unit of luminous intensity and is maintained at NPL using standard photometers and lamps with an uncertainty of ±0.2%. Working reference standards are calibrated against the standard photometers whose calibration derives in turn from the NPL spectral responsivity scale based on the cryogenic radiometer.
Luminous intensity measurements are carried out on a photometric bench. They compare the output of test lamps with that of working reference standard lamps using a specially constructed filter-corrected silicon photodiode (photometer).
Illuminance, (measured in lux), at a point of a surface is thequotient of luminous flux incident on an element of the surface, by the area of the element. For a point source and a surface normal to the direction of view, illuminance equals luminous intensity divided by distance squared.
Apparatus for illuminance measurements are similar to that for luminous intensity, but, instead of comparing lamps, the distances from light centres to the photometer are carefully measured for each lamp. The illuminance produced at the photometer by the standard is calculated using the inverse square law. The best measurement capability is ± 0.5%. This method can be used to calibrate photometers and luxmeters.

Total luminous flux (in lumen, lm) is a measure of theamount of light emitted from a source in all directions (i.e. the full solid angle of 4 π steradians). The NPL total luminous flux scale is derived at the ± 0.3% level from the luminous intensity scale by use of a specially constructed goniometer. The reference goniophotometer has a maximum detector to source distance of 18 m, which can permit very high angular resolution of large sources such as luminaries and spotlights. Luminance (in cd m-2) is a measure of the radiation emittedin a given direction from a given area of a source and can be thought of as a correlate of the visual attribute of ‘brightness’. The measurement scale is maintained in devices such as 'luminance gauges', which give a uniform field of luminance. The reference system at NPL uses a white diffuser of knowreflectance, illuminated normally by a luminous intensity standard at a measured distance.
A telephotometer designed to have a response close to the V(λ) function measures light reflected at 45º to the normal. The best measurement capability is ±1.5%. Colour temperature is a specification system describing the colour of a source by reference to a Planckianradiator scale. The appearance of coloured materials depends on the spectral properties of the illuminating source, so lamp colour temperature is quoted in several standards. A common requirement is the use of CIE Source A, defined as a tungsten source with a correlated colour temperature of 2856 K. NPL offers calibration services for the correlated colour temperature of tungsten lamps and for the calibration of meters for colour temperature and chroma measurements.
In addition to services for the calibration of sources supplied by customers, NPL can supply calibrated tungsten and tungsten halogen lamps, including a range of lamps designed specifically for use as standards of luminous intensity or luminous flux.
Throwing Light on the Use and Abuse of Luxmeters Luxmeters are a common sight in industry and science. Lighting engineers use them not only to check illuminance levels in offices and factories but also to make performance checks on the lighting used in transport, photographic and film studios, hospital operating theatres and so on. There are even applications in the aerospace industry, for materials testing and the design of cockpit displays in aircraft.
However, it is seldom appreciated that while the digital displays on these instruments often indicate fractions of a per cent, the accuracy of meters used in most practical applications is seldom better than 10%.
The principal reason for this is the difficulty in matching the spectral response curve of the detector to the eye's response function, V(λ). This means that even if the meter has been accurately and traceably calibrated using a tungsten lamp - as recommended in most specifications - errors will occur when it is used to measure other types of source with a different spectral distribution, such as fluorescent lamps. NPL has extensive expertise and specialist facilities available to address this problem. These range from advice and training in the optimum use of luxmeters, through accurate calibration of customers' meters to allow fully for the effects of the spectral mismatch, to the supply of special individually- designed photometers for applications where the very highest accuracies are required.







Moving Mirror Goniophotometer

System Configuration
Goniophotometric System:
Goniometric Rotating Console: Japanese Mitsubishi Motor and German Angle encoder
System to keep the test accuracy to 0.0017degree. Far Field Test (Near Field Test is option)
High Reflective Moving Mirror: Special design and produced to keep high reflective value.
Goniometric Rotating Control Instrument in 19inch cabinet: It connects to the PC and was controlled by the software.
Goniometric Rotating Control Instrument in dark room: This can allow the customer to control the rotating in the dark room when install the lumainires but no need to control in the PC.
Double Channel & High Precision Photometer
Class A Constant Temperature Photo Detector (Option is Class L)
Cross-beam Laser System for Calibrating


Measurement Principle
Moving Mirror Goniophotometer (also called Goniophotometer with Rotating Mirror) can test luminaries rotating in the prescribed burning position and around the vertical axle and a reflecting mirror rotates around the horizontal axle, meanwhile, a synchronous axle will rotate toward the opposite direction synchronously. The combined motion of the luminaries and mirror permit luminous measurement at the direction of any horizontal or vertical angle without tilting the luminaries, therefore, the luminous intensity will be not variation. The photometer head located at a fixed position of the limiting photometric distance in front of the reflecting mirror to gather the light in each direction.
The rotation priority is determined by the software. If mirror axle is took precedence of rotation, the goniophotometer will continuously measure the luminous intensity at each γ angle on a vertical plane determined by the C angle, the measuring trace is equivalent to the longitude. Similarly, while the luminaries axle is priority, the system will continuously measure the luminous intensity at each C angle on a conical surface determined by the γ angle, the trace can be looked upon the woof. See the following figure.
Moving Mirror Goniophotometer
The LSG-2000 full meet LM-79 Clause 9.3.1, CIE and GB standards for Goniophotometric of luminaries, this system is used to measure spatial luminous intensity distribution of luminaries for floodlight, street lighting and interior lighting, and other photometric parameters such as spatial iso-intensity curve, intensity distribution curve of each section (shown in rectangular coordinate system or polar coordinate system), iso-illuminance distribution curve, luminance limitation curve, luminaries efficiency, glare grade, effective beam angles, upward luminous flux ratio, downward luminous flux ratio, total luminous flux, effective luminous flux, utilization factor and electric parameters (wattage, power factor, voltage and current) of luminaries etc. The measured data may be saved in formats IES, LDT (Eulumdat), CIB, TM4, CIE, CEN and CSV for application software of lighting calculation and reflector design.

Laboratory Requirements
Room Requirements according to CIE
A. Dark Room for Goniometric Rotating Console
Dimension: W5.0m*L5.0m*H5.9m
B. Dark Room for Photometric Light Path
Dimension: W1.5m*H1.5m*L (15m – 30m)
C. Operating Room
Dimension: no less than W3m*L3m
*The dark room wall, ceiling and floor should be all coated with dull black paint or be covered by black cloth and black carpet.
*Air-conditioner: be set in the dark room to control the temperature around lamps to the standard value upon the CIE requirements.
Note: LISUN GROUP

ผลลัพธ์ (อังกฤษ) 2:

Principles of photometry
photometry is the measurement of Electromagnetic Radiation weighted by the Human Eye's response. This response changes with wavelength, and to an extent, from person to person. Internationally-agreed standard observer functions are therefore used in order to provide a consistent measurement base for photometry; the two most widely used are the V (λ) function, which applies for photopic vision (typical day-time light levels) and the V '(λ) for scotopic vision (low lighting levels). At Intermediate Light levels (Mesopic or 'Twilight' levels, such as Found on Lit roads at Night), the CIE System of Mesopic photometry is used to provide a Smooth transition between these Two functions. In photometry, the Word 'Luminous' is used. to indicate that measurements have been made ​​using a detection system (called a photometer) that has a spectral response similar to that of a human eye. The two principal photometric scales maintained at NPL are of luminous intensity and luminous flux. Setting up appropriate geometries permits calibrations of other quantities, such as luminance from luminous intensity standards. NPL has extensive facilities available for the photometric measurement of both sources and detectors, including photometers, luxmeters, luminance meters and colour temperature meters. Services include the calibration of Luminous Intensity, illuminance, luminance, Colour Temperature Luminous flux and correlated. Luminous Intensity Luminous measures the output from a Source ina specific direction Into UNIT Solid Angle. The candela (one of the SI base units, abbreviation cd), is the unit of luminous intensity and is maintained at NPL using standard photometers and lamps with an uncertainty of ± 0.2%. Standards are calibrated against the working reference standard photometers calibration derives in turn from the NPL whose spectral responsivity scale based on the cryogenic Radiometer. Luminous Intensity photometric measurements are carried out on a Bench. They compare the output of Test lamps with that of working reference standard lamps using a specially constructed Filter-corrected Silicon photodiode (photometer). illuminance, (measured in Lux), at a Point of a surface is Thequotient of Luminous flux Incident on an element. of the surface, by the area of the element. For a Point Source and a surface Normal to the direction of View, illuminance equals Luminous Intensity divided by Distance Squared. Apparatus for illuminance measurements are similar to that for Luminous Intensity, but, instead of comparing lamps, the distances from Light Centres to the photometer. are carefully measured for each lamp. The illuminance produced at the photometer by the standard is calculated using the inverse square law. The best measurement capability is ± 0.5%. Can this method be used to Calibrate photometers and Luxmeters. Total Luminous flux (in Lumen, LM) is a measure of Theamount of Light emitted from a Source in all Directions (IE the full Solid Angle of Steradians p 4). The NPL total luminous flux scale is derived at the ± 0.3% level from the luminous intensity scale by use of a specially constructed goniometer. The reference goniophotometer has a maximum detector to source distance of 18 m, which can permit very high angular resolution of large sources such as luminaries and spotlights. Luminance (in cd m-2) is a measure of the radiation emittedin a given direction from a given area of a source and can be thought of as a correlate of the visual attribute of 'brightness'. The measurement scale is maintained in devices such as 'luminance gauges', which give a uniform field of luminance. NPL at the reference System uses a diffuser of Knowreflectance White, normally Illuminated by a Luminous Intensity standard measured at a Distance. A Telephotometer designed to have a response close to the V (lambda) function measures Light reflected at 45º to the Normal. The best measurement capability is ± 1.5%. Colour temperature is a specification system describing the colour of a source by reference to a Planckianradiator scale. The appearance of coloured materials depends on the spectral properties of the illuminating source, so lamp colour temperature is quoted in several standards. A common requirement is the use of CIE Source A, defined as a tungsten source with a correlated colour temperature of 2856 K. NPL offers calibration services for the correlated colour temperature of tungsten lamps and for the calibration of meters for colour temperature and chroma measurements. in addition to Services for the calibration of sources supplied by customers, NPL Can Supply calibrated Tungsten and Tungsten halogen lamps, including a Range of lamps designed specifically for use as Standards of Luminous Intensity or Luminous flux. Throwing Light on the Use and Abuse of Luxmeters. Luxmeters are a common sight in industry and science. Lighting engineers use them not only to check illuminance levels in offices and factories but also to make performance checks on the lighting used in transport, photographic and film studios, hospital operating theatres and so on. There are even Applications in the Aerospace Industry, for Materials Testing and the Design of Cockpit displays in Aircraft. However, it is seldom appreciated that while the Digital displays on these Instruments often indicate fractions of a per cent, the accuracy of meters used in Most. Applications seldom practical is better than 10%. The Principal Reason for this is the difficulty in Matching the spectral response of the Curve Detector to the Eye's response function, V (lambda). This means that even if the meter has been accurately and traceably calibrated using a tungsten lamp - as recommended in most specifications - errors will occur when it is used to measure other types of source with a different spectral distribution, such as fluorescent lamps. NPL has extensive expertise and specialist facilities available to address this problem. These range from advice and training in the optimum use of luxmeters, through accurate calibration of customers' meters to allow fully for the effects of the spectral mismatch, to the supply of special individually- designed photometers for applications where the very highest accuracies are required. Moving Mirror Goniophotometer System Configuration Goniophotometric System: Rotating Goniometric Console: Japanese Mitsubishi Motor and German Angle Encoder System to Keep the Test accuracy to 0.0017degree. Far Field Test (Near Field Test is Option) High Reflective Moving Mirror: Special Design and produced to Keep High reflective Value. Goniometric Rotating Control Instrument in 19inch Cabinet: It Connects to the PC and was controlled by the Software. Goniometric Rotating Control Instrument in. Dark Room: This Can Allow the customer to Control the Rotating in the Dark Room when Install the Lumainires but no Need to Control in the PC. Double Channel & High Precision Photometer Class A Constant Temperature Photo Detector (Option is Class L) Cross-Beam. Laser System for Calibrating Measurement Principle Moving Mirror Goniophotometer (also Called Goniophotometer with Rotating Mirror) Can Test luminaries Rotating in the prescribed Burning position and Around the Vertical axle and a Reflecting Mirror rotates Around the horizontal axle, Meanwhile, a synchronous axle Will Rotate toward the. opposite direction synchronously. The combined motion of the luminaries and mirror permit luminous measurement at the direction of any horizontal or vertical angle without tilting the luminaries, therefore, the luminous intensity will be not variation. The Head photometer located at a fixed position of the limiting photometric Distance in Front of the Mirror to gather Reflecting the Light in each direction. The Rotation Priority is determined by the Software. If mirror axle is took precedence of rotation, the goniophotometer will continuously measure the luminous intensity at each γ angle on a vertical plane determined by the C angle, the measuring trace is equivalent to the longitude. Similarly, while the luminaries axle is priority, the system will continuously measure the luminous intensity at each C angle on a conical surface determined by the γ angle, the trace can be looked upon the woof. See the following figure. Moving Mirror Goniophotometer The LSG in 2000 full-LM-79 Meet Clause 9.3.1, CIE and GB Standards for Goniophotometric of luminaries, this System is used to measure Spatial Luminous Intensity Distribution of luminaries for Floodlight, Street Lighting and Interior. lighting, and other photometric parameters such as spatial iso-intensity curve, intensity distribution curve of each section (shown in rectangular coordinate system or polar coordinate system), iso-illuminance distribution curve, luminance limitation curve, luminaries efficiency, glare grade, effective beam. angles, upward luminous flux ratio, downward luminous flux ratio, total luminous flux, effective luminous flux, utilization factor and electric parameters (wattage, power factor, voltage and current) of luminaries etc. The measured data may be saved in formats IES, LDT. (Eulumdat), CIB, TM4, CIE, CEN and CSV Application Software for Calculation of Lighting Design and reflector. Laboratory Requirements Requirements according to CIE Room A. Dark Room for Goniometric Rotating Console Dimension: W5.0m * * H5.9m L5.0m B. Dark Room for Photometric Light Path Dimension: W1.5m H1.5m * L * (15m - 30m) C. Operating Room Dimension: no less than w3m * L3m * The Dark Room Wall, ceiling and floor should be all coated with Dull Black Paint or be covered by Black Cloth and Black Carpet. * Air-Conditioner: be SET in the Dark Room to Control. Temperature Around the lamps to the standard CIE Value upon the requirements. Note: LISUN GROUP.

ผลลัพธ์ (อังกฤษ) 3:

The rotation priority is determined by the software. If mirror axle is took precedence of rotation the goniophotometer,, Will continuously measure the luminous intensity at each γ angle on a vertical plane determined by the C angle the measuring,, Trace is equivalent to the longitude. Similarly while the, luminaries axle, is priorityPrinciples of Photometry
Photometry is the measurement of Electromagnetic radiation weighted by the human eye 's, response. This response changes, with wavelength and to an extent from person, to person. Internationally-agreed standard observer. Functions are therefore used in order to provide a consistent measurement base for photometry; the two most widely used. Are the V (λ), functionWhich applies for photopic vision (typical day-time light levels) and the V '(λ) for scotopic vision (low lighting levels).? At intermediate light levels (mesopic or 'Twilight', levels such as found on lit roads at night), the CIE system of mesopic. Photometry is used to provide a smooth transition between these two functions.

, In photometryThe word 'luminous' is used to indicate that measurements have been made using a detection system (called a photometer). That has a spectral response similar to that of a human eye. The two principal photometric scales maintained at NPL are. Of luminous intensity and luminous flux. Setting up appropriate geometries permits calibrations of, other quantitiesSuch as luminance from luminous intensity standards. NPL has extensive facilities available for the photometric measurement. Of both sources and detectors including photometers,,, meters luxmeters luminance and colour temperature meters. Services. Include the calibration of luminous intensity illuminance luminance luminous flux,,, and correlated colour temperature.
.Luminous intensity measures the luminous output from a source ina specific direction into unit solid angle. The candela. (one of the SI, base units abbreviation CD), is the unit of luminous intensity and is maintained at NPL using standard photometers. And lamps with an uncertainty of edge 0.2%.Working reference standards are calibrated against the standard photometers whose calibration derives in turn from the. NPL spectral responsivity scale based on the cryogenic radiometer.
Luminous intensity measurements are carried out on a. Photometric bench.They compare the output of test lamps with that of working reference standard lamps using a specially constructed filter-corrected. Silicon photodiode (photometer).
Illuminance, (measured in Lux), at a point of a surface is thequotient of luminous flux. Incident on an element of, the surface by the area of the element. For a point source and a surface normal to the direction. Of, viewIlluminance equals luminous intensity divided by distance squared.
Apparatus for illuminance measurements are similar to. That for, luminous intensity but instead of, comparing lamps the distances, from light centres to the photometer are carefully. Measured for each lamp. The illuminance produced at the photometer by the standard is calculated using the inverse square. Law.3% level from the luminous intensity scale by use of a specially constructed goniometer. The reference goniophotometer. Has a maximum detector to source distance of 18 m which can, permit very high angular resolution of large sources such as. Luminaries and spotlights.The best measurement capability is edge 0.5%. This method can be used to calibrate photometers and luxmeters.

Total luminous. Flux (in lumen LM), is a measure of theamount of light emitted from a source in all directions (i.e. The full solid angle. Of 4 π steradians). The NPL total luminous flux scale is derived at the edge 0.Luminance (in CD m-2) is a measure of the radiation emittedin a given direction from a given area of a source and can be. Thought of as a correlate of the visual attribute of 'brightness'. The measurement scale is maintained in devices such as. 'luminance gauges', which give a uniform field of luminance. The reference system at NPL uses a white diffuser, of knowreflectanceIlluminated normally by a luminous intensity standard at a measured distance.
A telephotometer designed to have a response. Close to the V (λ) function measures light reflected at 45 º to the normal. The best measurement capability is edge 1.5%. Colour. Temperature is a specification system describing the colour of a source by reference to a Planckianradiator scale.The appearance of coloured materials depends on the spectral properties of the, illuminating source so lamp colour temperature. Is quoted in several standards. A common requirement is the use of CIE Source A defined as, a tungsten source with a correlated. Colour temperature of 2856 K.NPL offers calibration services for the correlated colour temperature of tungsten lamps and for the calibration of meters. For colour temperature and chroma measurements.
In addition to services for the calibration of sources supplied, by customers. NPL can supply calibrated tungsten and tungsten, halogen lampsIncluding a range of lamps designed specifically for use as standards of luminous intensity or luminous flux.
Throwing. Light on the Use and Abuse of Luxmeters Luxmeters are a common sight in industry and science. Lighting engineers use them. Not only to check illuminance levels in offices and factories but also to make performance checks on the lighting used in. Transport.Photographic and, film studios hospital operating theatres and so on. There are even applications in the, aerospace industry. For materials testing and the design of cockpit displays in aircraft.
However it is, seldom appreciated that while the digital. Displays on these instruments often indicate fractions of a, per centThe accuracy of meters used in most practical applications is seldom better than 10%.
The principal reason for this is. The difficulty in matching the spectral response curve of the detector to the eye 's, response function V (λ).This means that even if the meter has been accurately and traceably calibrated using a tungsten lamp - as recommended in. Most specifications - errors will occur when it is used to measure other types of source with a different, spectral distribution. Such as fluorescent lamps. NPL has extensive expertise and specialist facilities available to address this problem.These range from advice and training in the optimum use of luxmeters through accurate, calibration of customers meters. ' To allow fully for the effects of the spectral mismatch to the, supply of special individually - designed photometers for. Applications where the very highest accuracies are required.









System Moving Mirror Goniophotometer Configuration
Goniophotometric. System:
.Goniometric Rotating Console: Japanese Mitsubishi Motor and German Angle encoder
System to keep the test accuracy to, 0.0017degree. Far Field Test (Near Field Test is option)
High Reflective Moving Mirror: Special design and produced to keep high reflective. Value.
Goniometric Rotating Control Instrument in 19inch cabinet: It connects to the PC and was controlled by the software.
.Goniometric Rotating Control Instrument in dark room: This can allow the customer to control the rotating in the dark room. When install the lumainires but no need to control in the PC.
Double Channel & High Precision Photometer
Class A Constant. Temperature Photo Detector (Option is Class L)
Cross-beam Laser System for Calibrating


Measurement Principle
.Moving Mirror Goniophotometer (also called Goniophotometer with Rotating Mirror) can test luminaries rotating in the prescribed. Burning position and around the vertical axle and a reflecting mirror rotates around the horizontal axle meanwhile a synchronous,,, Axle will rotate toward the opposite direction synchronously.The combined motion of the luminaries and mirror permit luminous measurement at the direction of any horizontal or vertical. Angle without tilting, the luminaries therefore the luminous, intensity will be not variation. The photometer head located. At a fixed position of the limiting photometric distance in front of the reflecting mirror to gather the light in each direction.
.The rotation priority is determined by the software. If mirror axle is took precedence of rotation the goniophotometer,, Will continuously measure the luminous intensity at each γ angle on a vertical plane determined by the C angle the measuring,, Trace is equivalent to the longitude. Similarly while the, luminaries axle, is priorityThe system will continuously measure the luminous intensity at each C angle on a conical surface determined by the, γ angle. The trace can be looked upon the woof. See the following figure.

Moving Mirror Goniophotometer The LSG-2000 full meet LM-79. Clause 9.3.1 CIE and, GB standards for Goniophotometric, of luminariesThis system is used to measure spatial luminous intensity distribution of luminaries, for floodlight street lighting and. Interior lighting and other, photometric parameters such as spatial, iso-intensity curve intensity distribution curve of. Each section (shown in rectangular coordinate system or polar coordinate system), iso-illuminance, distribution curve luminance. Limitation, curveEfficiency luminaries, grade glare, beam, effective angles upward luminous flux ratio downward luminous flux ratio total,,, Luminous flux effective flux, luminous, factor utilization and electric parameters (wattage power, and, factor voltage current). Of luminaries etc. The measured data may be saved in, formats IES LDT (Eulumdat), CIB TM4 CIE,,,CEN and CSV for application software of lighting calculation and reflector design.


Laboratory Requirements Room Requirements. According to CIE
A. Dark Room for Goniometric Rotating Console
Dimension: W5.0m * L5.0m * H5.9m
B. Dark Room for Photometric. Light Path
Dimension: W1.5m * * L H1.5m (15m - 30m)
C. Operating Room
Dimension: no less than W3m * L3m
* The dark, room wallCeiling and floor should be all coated with dull black paint or be covered by black cloth and black carpet.
* Air-conditioner:? Be set in the dark room to control the temperature around lamps to the standard value upon the CIE requirements.
Note:? LISUN GROUP.