In every image projected by an optical or electro-optical system, the irradiance varies from the centre to the edge independently of the object structures. It generally decreases, i.e., even an object surface of uniform radiance will be imaged with an irradiance which decreases from the image centre to the edge.
ISO 13653 discusses standards for optics and photonics. ISO 13653 refers to the relative irradiance in the image field. ISO 13653 specifies general optical test methods for the measurement of the relative irradiance in the image field.
ISO 13653 is applicable to optical imaging systems in the optical spectral region from λ = 100 nm to λ = 1 μm. Theoretical reflections and the comparison with the calculation apply only to optical systems. ISO 13653 is also applicable to rotationally invariant and rotationally variant systems, anamorphic systems.
ISO 13653 is also applicable to the determination of the relative radiant power. As far as measurements are concerned, ISO 13653 is also applicable to electro-optical systems. The two methods described differing particularly in the influence of veiling glare.
ISO 13653 on image irradiance in optical systems is applicable to:
The irradiance produced at image points in any lossless optical system by an extended diffuse radiator of given radiant emittance is determined by the final pencil of rays and the indices of refraction of object and image space and can easily be calculated using thermodynamic reciprocity.
ISO 13653 describes factors influencing the relative irradiance. ISO 13653 includes classification of the measurement procedures for relative irradiance in the image field. Two different measurement procedures are generally acceptable such as irradiance measurement and radiant power measurement.
BS ISO 13653:2019 specifies graphs and formulas which are given to show the degree to which parabolic and spherical reflectors depart from the usual paraxial irradiance formulas when an extended source or a small source is placed near the aperture. Overall, ISO 13653 guides you for determination of image irradiance in optical systems.
BS ISO 13653:2019 supersedes BS ISO 13653:1996, which is withdrawn. BS ISO 13653:2019 has a change compared to the BS ISO 13653:1996 are as follows: A second option for measurement, which does not require a rotation of the specimen but allows to measure along with an image diameter, has been included in 7.2.3.
ISO 13653