JJG 952-2000 Verification Procedure for Interpupillary Distance Meters JJG952-2000 Standard download decompression password: www.bzxz.net
This procedure applies to the initial verification, subsequent verification and in-use inspection of interpupillary distance meters.

National Metrology Verification Regulation of the People's Republic of China JJG952—2000
Pupil Distance Meter
2000—05—08 Issued
2000—10-01 Implementation
State Administration of Quality and Technical Supervision Issued
J.IG,952-20m0
Verification Regulation of Pupit Distance Meter
Meter
JJG952-2000
This regulation was approved by the State Administration of Quality and Technical Supervision on May 8, 2000, and will be implemented from October 1, 2001.
Original unit: National Optical Meter Technical Committee Drafting unit: China Institute of Metrology This regulation is entrusted to the National Optical Meter Technical Committee for interpretation. Main drafters of this regulation:
Shi Jiaoru
Song Jianping
Meng Jia Drafting person:
Ma Zhenye
JJG 952-1000
(China Institute of Metrology)
(China Institute of Metrology)
(China Institute of Metrology)
General speed·
Metering performance requirements
Indication error
Asymmetry error
Round-off error
General technical requirements
Appearance requirements
Illumination uniformity·
Reward capability
Control of measuring instruments·
Verification cases
Verification items and verification methods
Handling of verification results
Verification cycle
Appendix A
Control record of abdominal distance meter
JJG 952—20DD
Appendix B Tachymeter Calibration Certificate (Back) Format
1 Scope
J3G 952 - 20
Tachometer Calibration Procedure
This procedure applies to the initial inspection, subsequent inspection and in-use inspection of tachymeters. 2 Description
A tachymeter is a measuring instrument used to measure the distance between the two eye holes of a person's eyes during the process of eyeglass fitting. Optometry and spectacles fitting: Generally, it is necessary to correct the vision of the customer in two fast states: near vision and selective vision. Therefore, the pupil distance measurement actually includes the measurement of the customer's pupil when they are far away and the measurement of the pupil when they are near. Usually, the distance of 5m or more is measured. The distance selected as the human eye limit is 300mm, and the working distance is 300mm as the human eye limit. When the human eye sees an object, an image is formed on the retina. The line connecting the object point and the center of the retina is called the visual axis. Although the optical axis of the human eye is very close to the visual axis, it does not coincide. Artificial measurement of visual distance refers to the optometrist using a ruler to directly measure the distance from the outside (or inside) of the patient's eye to the inside (or outside) of the eye, or the distance from the center of the eye to the center of the eye (Figure 1, the symbol PD represents the distance. Figure! Schematic diagram of artificial measurement of visual distance
Due to the different professions of the operator, the measurement and calculation of near distance varies from person to person: for example, the near working distance of a person working at a desk is different from that of a computer operator, and the near working distance of a pianist and a violinist is different, so the calculated near distance will also be different. The calculation and determination of the near pupil distance can refer to formula (1)
NC = P×L+h+R
. In order to eliminate the manual measurement error of the optometrist and the error caused by the measurement and conversion difference of the near and far sighting distances, the most effective method is to make the pupil distance objective and accurate. The tachograph is mainly composed of four parts: the optical display and its control system, the optical system, the electromechanical system and the computer components. The measurement principle of the tachograph is: the sight mark illuminated by the light source is imaged by the optical system at a certain working distance in front of the patient's eyes. When the patient looks at the sight mark, the visual axis of the left eye intersects at this specific working distance. At this time, the light forms a spot on the surface of the left and right corneas of the patient. The optometrist can see the reading spring and the two reflective points at the same time through the eyepiece. After moving the left and right reading springs to face the reflective points of the patient's left eye respectively, the patient's following distance can be obtained on the display screen: wwW.bzxz.Net
According to the principle of optometry, the telemeter only needs to measure the patient's far following distance, and the near following distance can be obtained through conversion. That is: after measuring the patient's far following distance at the infinite working position, select the appropriate near working distance according to the patient's condition and adjust it to the corresponding working position: At this time, the number on the display screen is the patient's near following distance at the near working distance. In actual work, the near following distance should also be determined by the optometrist based on the patient's condition, the data of the telemeter and the actual observation results.
3 Metrological performance requirements
3.1 Indication error
The absolute value of the indication error of the tachymeter shall not exceed 0.5mm3.2 Asymmetry error
The absolute value of the asymmetry error of the tachymeter between the left and right sides shall not exceed 0.5mm13.3 Inclusion error
The absolute value of the error of the tachymeter from the far distance to the near distance shall not exceed 0.5mm. 4 General technical requirements
4.1 Visual requirements
4.1.1 The tachymeter shall have a nameplate with the instrument name, model, manufacturer, instrument number and production date, and the center of the instrument. The nameplate shall be the same and the handwriting shall be clear: 4.1.2 The appearance of the tachymeter shall be neat and intact, and shall not have corrosion, peeling, abrasions and other defects. The reading and the measured person's window are uniform, without oil, water, mildew and other defects that affect observation and reading. 4.1.3 All parts are working properly. The positioning spring moves smoothly: no jumping: 4.2 Illumination uniformity
The internal illumination of the optical microscope is uniform, and there shall be no stray light of any shape. The optometrist observes the reflection of the patient's cornea.
4.3 Measurement ability
4.3, 1 This instrument should have the ability to perform one-way measurement and reading with the left and right eyes. The range of the optical microscope should be between 50mm-80mm, including infinite, 2m, 1m4.3.2
50cm, 40em, 30em and other working distance measurement positions. 4.3.3 The minimum reading of the distance meter shall not exceed 0.5mm. 5. Control of measuring instruments This includes the initial calibration, subsequent calibration and in-use inspection. 5.1 Calibration conditions 5.1.1 Calibration equipment 5.1.1- This calibration device The distance meter calibration device consists of an adjustable workbench with two-dimensional motion direction and "three standard distance measuring sets" with nominal distance values ​​of 55, 65m and 75m. The difference between the actual center distance value and the theoretical center distance value of the three standard sets should be controlled within 0.1mm. 5.1.1.2 Special simulation suit The distance meter calibration device is equipped with a standard simulation suit of 0.01 mm to simulate the working state. The area of ​​the light spot observed from the patient's eye is the standard image. 5.1.2 Calibration environment conditions: (2 -5)
5.1.2.2 Relative degree: 85%
3.2 Inspection items and inspection methods
5,2.1 Standard determination of pre-11
light items H
Xin Ke determination
Subsequent inspection
Make the state
light items day
show error
asymmetric ten·plan difference
distinguishing difference
long-term effective determination
JJG953—·200
table!
F inspection
Note: H is the nature of the small "middle" determination, not the whole company's ". 5.2.2 Method of determination
3.2.2.1 Verification according to technical requirements
Combined with visual observation and dynamic inspection, the inspection shall be carried out as required by 4.1-4.3, and the inspection results shall be recorded in the original records.
5.2.2.3 Indication error detection
Put two standard simulation limits in the three standard sets with nominal distances of 55mm1, 65mm and 75mm in the verification device in turn, and set the working gear of the special inspection rangefinder to the infinite distance gear, and then measure and read the values ​​respectively; each group is required to measure 3 times, and the deviation between the measured average value and the nominal value is the indication error. The range of indication error shall not be greater than 0.5mm according to the provisions of 3.1. 5.2.2.3: Standard calibration for error elimination
Use the standard analog on the calibration device to perform unidirectional measurement using a tachograph. Read 3 times in each direction. The difference between the average value of the reading in the non-unidirectional direction and the average value of the reading in the directional direction is 1/3, which is the asymmetry error of the distance. The absolute value of the asymmetry error shall not exceed 0.5 according to the provisions of 3.2. When measuring this indicator, the parallax of the measurement personnel shall be carefully observed. The inspector shall center the observation window and eliminate the parallax of the body by taking the half-mean method of multiple single measurements. 5.2.2.4 The near-field error shall be converted to the specified distance. On the "no-operation" night vision system, the calibration shall be arbitrarily set to one of the three values ​​of 55m1, G51rm and 75trm, respectively. Then the working position shall be transferred to the 30m1011, 50, 1m and 2㎡ positions available around the instrument in turn, and the actual readings of each position shall be observed and recorded respectively. They shall be compared with the theoretical values ​​of each position (Table 2). The difference between the theoretical value and the actual reading shall be the error of the instrument: the absolute confidence interval including the error shall be calculated based on the provisions of 3.3. The error shall be 0.5mm.1
30 cta
JJC 953—2000
Table 2 Theoretical range of near vision distance obtained from far vision distance PDSS
2 In which D55, D65 and PD75 represent the three near vision values ​​available for selection. The data in the same column represent the theoretical values ​​of the far vision value converted to different working positions, which are calculated according to formula (1). 5.3 Processing of verification results
Record the data measured during verification according to the table in Appendix A, calculate the deviation, and then judge whether it is qualified according to the actual requirements. For the first time, all the standards are qualified according to the specified distance requirements: for the subsequent verification and the distance tested in use, the three indicators of indication error, asymmetry error between the left and right eyes and combined error must be qualified to determine The certificate shall indicate whether all indicators have met the performance requirements or general technical requirements: a qualified distance meter shall be issued a calibration certificate, and an unqualified distance meter shall be issued a calibration non-conformity notice, and the unqualified items shall be noted:
5.4 Calibration period
Only for the calibration of pupil distance, the period shall generally not exceed "years. Appendix A
Model specification
Instrument number
Inspection unit
Appearance inspection
Measurement position
Certificate number
Record number
Value error (mm)
Measured at different distances but
Nominal
Comparison station
Calibrator
J3G 952--2000
Calibration record of telescope
Calibration basis
Calibration transfer
Production unit
Period average and
Telescope control procedure
Relative humidity unit
Minimum reading distance
Distance to near vision error [mm
Average value error
Working volume
30 crm
Asymmetry error (mm)
Left eye
Predicted based on this work
Calibrator
Average value
Measurement value
Right eye distance
Calibration date
Valid until
Theoretical value
Combined error
Incompatibility
Appendix B
1. Appearance:
2. Eye distance measurement range:
3 Numerical error:
4, Left eye asymmetry error:
JFG 952—2000
Pupillary distance meter calibration certificate (back) format
5, Rounding error when converting far visual distance to near visual distance: mm
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