When measuring the intensity of light, the size of the light source should be small compared to the photometric distance. In this case, the law of squares of distance is fulfilled, which can be applied in practice and obtain high measurement accuracy if the photometry distance exceeds the largest size of the light source by at least 10 times. For light sources with finite dimensions at small distances to the illuminated surface, this law must be amended. This paper presents the results of calculations of errors when using the law of squares of distance for light sources of finite sizes of various shapes and various light distributions.

Keywords: the law of squares of distance, luminous intensity, measurement error, photometry distance.

Prism spectral devices have a spectrum-variable dispersion and therefore a nonlinear relationship between the wavelength and the position of spectral lines on the focal surface of a spectral monochromator device, which makes it difficult to calibrate such devices in terms of wavelengths and dispersion.Most often, the well-known Hartmat formula is used for graduation. However, the accuracy of its calculation is satisfactory only in a limited spectral range, and therefore the calculation is carried out on overlapping areas no wider than 200 nm with averaging in overlapping zones. Averaging gives a calibration curve (and, accordingly, a dispersion curve) with gaps at the joints. In this paper, we consider the possibility of using a single calibration for the entire spectrum region, providing smooth, continuous calibration curves. The best result is obtained by using the Hartmann formula for the entire spectral range, after which a set of deviations of the calibration points is determined. This set is interpolated by a polynomial of an arbitrarily chosen order n using the least squares method.

Keywords: monochromator, spectrum, calibration, dispersion, Hartmann formula, interpolation, polynomial

The operability of an optical device depends entirely on the quality of the optical parts that make up the optical system. Timely measurement of errors of optical parts in the process of surface shaping organizes feedback: the more accurately the error is measured, the more accurately the correction of the geometry of the surface is possible. Errors of optical surfaces and optical systems in general can be estimated by the mismatch of coordinates of real and ideal (calculated) profile curves of surfaces; mismatch of normals to this surface; difference of wave fronts in incident and refracted (or reflected) beams of light rays, etc.. The reproducibility of optical surfaces from sample to sample and their compliance with the calculated one is usually estimated by the discrepancy between the actual and theoretical functions of the course of light rays. Such a discrepancy is estimated by the aberrograms of optical systems, which are determined experimentally on special installations – aberrographs. Unlike the known schemes for measuring longitudinal aberrations of only reflectors or only lenses, the devel-oped installation is universal, designed to measure zonal aberrations of large-diameter mirror and lens lenses that are used in lighting devices, solar energy concentrators, transmitting and receiving optical systems of optoelectronic de-vices.

Keywords: aberrometer, aberrogram, longitudinal aberration, lens lens, mirror lens