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Currently, international measurements of the sun protection factor of sunscreen cosmetics rely primarily on calculations based on the test results of the ultraviolet spectrum transmittance of such cosmetics. It should be emphasized here that the testing of the ultraviolet spectrum transmittance of sun protection cosmetics is different from the testing of the ultraviolet spectrum transmittance of ordinary optical materials. An integrating sphere should be used as the receiver or ultraviolet radiation source in the UV protection tester, and it must meet the measurement geometry conditions of 0/d or d/0. After measuring the UV spectrum transmittance of the sun protection cosmetic, its SPF value can be calculated using a formula. http://www.kzwxcsy.com/upLoad/news/month_1507/201507221654237867.png Here, Eλ represents the relative influence of the erythema spectrum; Sλ is the spectral radiance of the sun, with units of W·m-1·nm-1; Tλ is the spectral transmittance of sunscreen cosmetics; and dλ is the wavelength interval. A sunscreen measuring instrument should be an ultraviolet-visible spectrophotometer with a 0/d or d/0 measurement geometry and scanning functionality. Once the geometric and spectral conditions of the measuring device are determined, its basic structure is also established. The general composition and structural block diagram of the measuring device are shown in the figure below. The figure shows the measurement schemes for spectrization first under the 0/d geometric condition (a) and then under the d/0 geometric condition (b); the main purpose of the radiation source is to provide sufficient and stable ultraviolet radiation energy for the tests. The monochromator disperses the ultraviolet radiation energy from the light source in order to perform spectroscopic measurements. The sample chamber can provide a mounting structure for the samples and minimize the impact of stray radiation. To enable the detector to receive as completely as possible the ultraviolet flux emitted in all directions from the sunscreen sample, a combination of an integrating sphere and a photomultiplier tube is used in the design. The signal output by the detector is amplified and processed before being fed into a computer for further signal processing. Take the method of spectrally separating first under 0/d geometric conditions as an example. The specific measurement process is as follows: the ultraviolet light emitted by the radiation source is dispersed by a monochromator and then converged by the optical path into a collimated beam, which enters from one side of the sample. The other side of the sample is in close contact with the window of the integrating sphere, so that the spectral radiant flux Φ0(λ) from all directions emerging from the sample is received by the integrating sphere. Using the same method, when no sample is placed, it is possible to measure the flux Φi(λ) incident on the sample. By calculation, the spectral transmittance τ(λ) of the sunscreen at specific wavelengths can be determined. By combining the aforementioned measurement steps with the use of a monochromator to scan through different wavelengths, the spectral transmittance at each wavelength can be obtained. Since some additives in sunscreens emit fluorescence under ultraviolet light, it is necessary to consider eliminating the influence of fluorescence measurements while taking into account the spectral and geometric conditions of the measuring device.