ISO 18490:2015 pdf download.Non-destructive testing — Evaluation of vision acuity of NDT personnel.
7 Test charts
Test charts shall be prepared in accordance with this International Standard. Charts shall be printed in black ink on white paper of an adequate quality and using equipment that ensures the print quality is suitahlc for the purpose. Charts shall he printed in black ink on white paper using equipment that ensures the print quality is suitable for the purpose. The printing equipment and the paper used shall be of an adequate quality for the purpose. This shall be verified practically by using magnifwation The two blocks ofoptolypes(see Annes A) have been developed to accommodate the ditkrent ypes of printing equipment commonly encountered. The block which prints best shall be used This can be determined under good lighting conditions using apiroximately lOs magnification. Inspect lines )and 10 and verify that the lincs forming the limbs of the F. characters on line 9 are all continuous and of an even appearance. There shall not be any spread of the print material such that the gaps between the limbs arc not visible. Line 10 characters may not all be perfectly formed due to the very small size and since it is not necessary to distinguish this line for compliance, the quality of this line does not form part of the acceptance criteria for the chart. It is. however, required that the overall shape of each optotype shall be discernible under magnification with the limbs and gaps being evident.
The size of the optotype is important and the prepared charts include size verification maris. Printed charts shall be verified tube the correct size by measurement. The annotated 250 mm distance between the defined marks shall be measured and shall not be less than 245 mm nor he more than 255 mm. Printing errors could affect vertical and horizontal scaling differently: therefore, before use, it shall be veritied that the basic shape of the individual optotype characters is square. This may be verified on the larger characters.
Test charts shall be prepared in accordance with this International Standard. Charts shall be printed in black ink on white paper of an adequate quality and using equipment that ensures the print quality is suitahlc for the purpose. Charts shall he printed in black ink on white paper using equipment that ensures the print quality is suitable for the purpose. The printing equipment and the paper used shall be of an adequate quality for the purpose. This shall be verified practically by using magnifwation The two blocks ofoptolypes(see Annes A) have been developed to accommodate the ditkrent ypes of printing equipment commonly encountered. The block which prints best shall be used This can be determined under good lighting conditions using apiroximately lOs magnification. Inspect lines )and 10 and verify that the lincs forming the limbs of the F. characters on line 9 are all continuous and of an even appearance. There shall not be any spread of the print material such that the gaps between the limbs arc not visible. Line 10 characters may not all be perfectly formed due to the very small size and since it is not necessary to distinguish this line for compliance, the quality of this line does not form part of the acceptance criteria for the chart. It is. however, required that the overall shape of each optotype shall be discernible under magnification with the limbs and gaps being evident.
The size of the optotype is important and the prepared charts include size verification maris. Printed charts shall be verified tube the correct size by measurement. The annotated 250 mm distance between the defined marks shall be measured and shall not be less than 245 mm nor he more than 255 mm. Printing errors could affect vertical and horizontal scaling differently: therefore, before use, it shall be veritied that the basic shape of the individual optotype characters is square. This may be verified on the larger characters.
