Sunglasses detection methods: focal to measure
Sunglasses belongs to the category of individual eye facial protection articles, to measure the quality of technical indicators mainly embodied in the top of coke, uv protection, mechanical impact, from several aspects such as being able to stop the dazzling glare. One is able to measure, top coke over the years, international on sunglasses dioptric power measurement has not been unified. By different measuring methods, measuring principle and measuring instrument as a result of the differences between the measurement results for the same product in different situation, raising the quality of the products, in turn, to rise to the dispute and technical barriers to trade, has affected the international trade. China as the production and use of sunglasses power, focal viscometer method has been used for many years. There are literature introduces the China institute of standardization of telescope and focal viscometer method measuring the consistency of the results between two different measurement methods the results of the study. However, the new ISO/CD12311 'sunglasses - General use mirror EN1836 international standard and the European Union: 2005 'the eye protection routine use of sunglasses and filter criteria are method is recommended to use a telescope. Last year at the international standard ISO standardization group sunglasses measurement standard working group meeting, the working group has proposed focal meter measuring method in our country to ISO sunglasses in the test method of international standard. Focal degree measurement method and the principle of (1) the telescope method accurately, telescope focal power measurement is sunglasses, namely, the reciprocal of after the lens focal length, refers to the lens after primary side to focus. Can use optical bench build telescope method experiment platform. The experiment platform is mainly composed of light source, the resolution of the board, aperture, object stage, auxiliary lens, reading microscope, such as slideway of seven parts. When measuring color sunglasses, you should choose white light source, and frosted glass is placed behind the light source, in order to make uniform beam. Measuring colorless with optical lenses, should add green broadband filter in front of the light source, in order to eliminate the color difference and increase with the comparability between the focal meter method. International standards ISO/CD12311 is recommended to use a fixed image of real target, on the optical bench measuring spherical plain sunglasses, should add the auxiliary lens in the optical path in order to help gather parallel to the incident light. International standards ISO/CD12311 recommended to measure the aperture of 20 mm. (2) focal viscometer method focal viscometer method measurement is after lens focal degrees, the lens after the reciprocal of the focal length, refers to the lens surface after vertex to the focal distance. (3) by the definition of two kinds of measuring principle of extended difference after lens focal power and lens focal degree on the definition of difference, and when the sample under test is thick lens, its principal plane and the surface is not in the same plane, so the focal length and back focal length is different, the focal power has been derived and the coke is also different. In general, the thin lens can be neglected.