The photon counters based on avalanche photodiodes feature a number of advantages, compared with those based on traditional photodetectors-photoelectric multipliers. This is essential when recording weak optical signals of a small duration with subnanosecond time resolution. Photon counting with industrial silicon photodiodes, as well as with the avalanche photodetectors based on a metal-dielectric-semiconductor structure, has been reported with a presentation of their main single-electron characteristics. The aim of this work is to study the quantum efficiency of recording and the threshold sensitivity of avalanche photodiodes in the photon counting mode.

The development of new physical principles and technology was the basis of creating fast- response one-quantum photomultipliers with subnanosecond time response. At the present time, the photoelectric multipliers of special designs have a resolution of 47 ps, namely: device R1564V-01 with microchannel plates and device VPM-154M with static crossed fields. It is sufficiently close to the limiting possibilities (several picoseconds) of the existing electronic equipment for multichannel time analyzing.

In various fields of science and engineering a need often arises to record images in a single- photon mode, especially if an addition to spatial information and analysis also demands time data. The last two decades have resulted in a wide development of photon television counters (PTC), incorporating an image converter (IC) and camera tube, matched together. The basic component of the PTC determining its parameters is an IC tube whose task consists in the maximum possible efficient conversion of the light quantum flux to photoelectrons, amplifying the latter with a minimum dispersion in space, time, and energy and, finally, converting the amplified photoelectrons to light flashes with the help of a phosphor, also with a minimum dispersion.

In the USSR there are two absolute methods of measuring the diffuse reflection spectral factors realized in two high-precision ethalon devices. Hence the unity of measurements requires the comparison of the measurement data obtained from these two devices. This work presents the results of comparisons of these two ethalon devices. We also describe the peculiarity of other main methods for absolute measurements of the diffuse reflection spectral factor.

For inspection and adjustment the sensitivity characteristics of the photoelectric devices (P E D) intended for star radiation registration, in laboratory practice the star imitators are used. These imitators provide reproduction of the corresponding levels of radiation of a definite spectral composition in a given dynamic range.

It is known that the energy distribution in the star spectrum is one of the most important characteristics of radiation. Traditionally Vega is taken for the fundamental spectrophotometric standard. In relation to Vega spectrum the network of the secondary standards, uniformly distributed over the sky, is created (see for example [1 ] ). Then, by the Vega and by these standards the data of measurements for other stars close by distributed to them by zenithal distance, are absolutized. The basic requirements to a standard are the radiation stability in time, because if the variation of the star standard is unknown or it is not taken into account during the observation data processing, then it leads to increasing the catalogues and actual measurements error. Besides, the standard star spectrum should be purely stellar. In other words, the star should not have any peculiarities in spectrum, it should not be fast rotator and it should be no dust and gas around it.

One of the basic optical characteristics, describing the light-diffusing properties of materials and coatings is a spatial indicatrix of reflection. When illuminating the studied sample of material from some fixed directions the reflection indicatrices are characterizing changes in the reflected flux intensity depending on angles of reflection. In this case the illumination direction for the materials and coating with isotropic surface properties is characterized by one, zenith angle €-j,counted off from the normal to a surface in the incidence plane (this plane contains the light incidence direction and normal to the sample surfaces) and the reflection direction -by two angles: a zenith angle e , counted off between the selected direction of reflection and the mentioned normal, as well as an azimuthal angle between the planes of incidence and reflection (the latter incorporates the reflection direction and normal to the sample surfaces) . Thus the devices usually referred to as goniophotometers, used for measuring the reflection indicatrices should have in accordance with the minimum number of measured function arguments, at least three degrees of freedom. allowing to change in respect to each other the relative angular positions of goniophotometer elements: the illuminant, sample and photometer (an instrument measuring the luminous intensity or the sample brightness in specified directions) . The stated three degrees of freedom are realized in the known designs of goniophotometers by various mechanical constructions with the use of a flat sample.

Black deep-dull enamel coatings are widely used in different fields of instrument engineering and this leads to the necessity of fast reliable inspection of reflection coefficient (luminance) of such coating in the interval less than 0.03. The solution of the task becomes rather difficult due to the fact that most commercially available instruments do not ensure the measurement of parameters to be inspected at the desired low level. An attempt was made to develop the procedure of fast inspection of the luminance reflection coefficient of black deep-dull enamel coating by means of a FOU photometer provided for reliable data with the values of the inspected parameter at a level of 0.015 and lower.

At the present time the testing of spectrophotometrical measuring means (spectrophotometers) in the ultraviolet and visible spectrum in accordance with the existing USSR verification scheme carried out by means of glass light filters, types KS-100, KS-102 certified with standard instruments. The main shortage of these light filters when using them as the standard measures is the necessity to certify them for transmission coefficient. To solve the problem, it seems reasonable to develop and use the liquid standard samples of optical density (LS) as highly efficient and economical means ensuring the unity of measurements in the spectrophotometry. In this report the possibility of utilization of the set of LS of optical density is considered. The set of LS represents acid and water solutions of organic compounds of five types (LS 04-1, LS 04-2, LS 04-3, LS 04-4, LS 04-5) having two levels of optical density in the wave band of 220 - 720 nm.

The method and apparatus for investigation of paper surface roughness have been developed. The method is based on depolarization oflinear-polarized light with orientation of electricvector in the plane ofincidence. Studies of surface roughness (smoothness) of some paper types by the above-mentioned method and friction method according to GOST standard (gas jet flow velocity) have been fulfilled by means of a standard device BEK. In addition paper surface roughness has been measured by means of scanning microscope ORIM-1. The results obtained vitness that optical measurements allow to register surface roughness, and smoothness measurement method according to GOST responds not only to surface roughness but also to other parameters, particularly to quantity of material per unit of surface area.

The automated optical system for the control of spatial distribution of the optical parameters of solids is developed. The possibilities of spectrophotometric method for detection of the low- contrast geometrical and physical inhomogeneities of dielectric, semiconducting and metal materials are investigated.

An express method for determination of spatial characteristics of laser radiation allowing us to reduce some operations in photometric process, and as a consequence to decrease systematic mistake and to accomplish the measurement faster, is described.

The main instrument for metrological control of the precise measurements for the incoherent optical radiation power characteristics is the black-body model (BBM), i.e., the heat radiator the power output of which can be calculated beforehand with sufficiently high accuracy. For obtaining a black-body model with the preset metrological characteristics, the procedures for optimization of the emitting cavities geometric parameters are worked out depending on the emissive properties of materials and required working temperatures. The main technical problem to be tackled when elaborating the black-body model is to ensure isothermal characteristics of its emitting cavity. In this case, when the temperature rises, the non- uniformity of heating reduces as a rule.

Beginning from the middle of the 1970s, specialists of the All-Union Research Institute for Optical and Physical Measurements widely employed thermoelectric effect for creating different types of optical radiation receivers. Especially suitable for the purpose proved to be thermoelectric receivers with thermocouples which can measure energy illumination intensity in a range from 1 to 3 (DOT) 10³ W/m². For more powerful radiation fluxes, the optimal thermoelectric receivers are those provided with the wire thermocouples having a power range of 10^-3 up to 10 W.

In the practice of spectrophotometric studies, a need often arises for measurements of the transmission and reflection factors of various diffusing objects. In the visible band of wavelengths, this problem has been practically solved by using a sphere photometer with an inner coating of BaSO₄ paint, or a polyvinyl alcohol, MgO, and others. For these aims, in the infrared region of the spectrum use is made, as a rule, of systems allowing us to concentrate on a photodetector with the radiation scattered by a specimen to the half-space. The sphere photometers, available at present for the infrared region, either are slightly efficient or may be applied in a comparatively narrow spectral range. We are suggesting specially treated aluminum as an inner coating for the sphere photometer surface. The factor of diffusion reflection of such a coating reaches 0.92 and is slightly selective up to 25 micrometers , the diffusion indicatrix is close to the Lambert one and remains unchanged in the entire stated interval, the deviation from the Lambert law at an oblique illumination of up to 70 degree(s) does not exceed 10%.

A compact nuclear radiation dosimetric complex consisting of a photodensitometer and three types of detectors based on the quartz glasses and permitting us to measure the transmittance of glasses having been irradiated by large doses up to 10⁸ Gy and to find the doses value by calibrating dependence between the transmittance of quartz glasses and the doses value is described.

The immersion lens (IL) influence on detecting ability D(lambda) ^* of Cd_xHg_1-xTe photodiodes designed for the IR range from 8 to 14 micrometers is considered. Theoretical dependencies of D(lambda) ^* and the threshold temperature difference (Delta) T_t of the IR imaging system on the limit wavelength (lambda) _co immersion photodiodes (IPh) are given. Affecting both a signal and noise of photodiodes the immersion increases their D(lambda) ^*. IR imaging systems with IPh become not so critical to the choice of (lambda) .

Real physical receivers, based on extrinsic and intrinsic photoeffect, are used practically in every spectral and photometric instrument. However, their current and voltage sensitivities provide a possibility for independent usage as the holders of the basic units of energetic photometry (W, J and their derivatives). At this case the simplicity of reproduction in units and possibility of prediction of not only the sensitivity itself but also the construction of the receivers with prescribed or known quantum output are important.

Use has been made of a technique to determine the distribution in atmosphere of the so-called optically active components (aerosol, ozone, water vapor, etc.) by the brightness profiles of atmosphere on a horizon, measured from space. Developed are the PHASE eight-channel aerospace teleradiometer and laboratory equipment for its study and graduation (including the complex for an absolute graduation and collimator for reading the characteristics of the teleradiometer field of vision). The PHASE teleradiometer has been installed on board of orbital complex `Salyut-7' - `Cosmos-1686' - `Sojuz-T14' and more than 10,000 brightness profiles were obtained over various regions of the Earth.

By simulation the influence of generation time delay, pattern-effect, and time jitter in an injection laser device on the dynamical information store process in the closed loop is investigated.

Traditionally neutral light filters are made of glass (HC6, H7, HC8, etc.). There exists thin film technology for neutral-gray filters production with the use of vacuum evaporation on transparent glass substrates. To minimize residual reflectivity it is desirable to fulfill the following relation between refraction factor n of MgF₂ layer and optical conductivity Z of metal-dielectric mixture on the glass substrate: Z((lambda) ) n, where (lambda) - is a wavelength. It is shown, that to reduce dispersion of Z((lambda) ) in the visible it is necessary to use low thickness of metal layers in NTFF, that is of 3 to 5 nm.

The photometric characteristics, especially the transmission and reflecting light factors of the materials are used widely and require accuracy and unity measurements during manufacture, usage and at studying their change under various factors. All the photometric devices and instruments intended for measuring the transmission and reflection light factors of the materials are graduated and checked in the period of operation with the use of sets of light filters and plates with known transmission and reflection factors respectively. Referred to the requirements to be met by these photometric devices and measuring facilities are spectral composition of light source radiation and spectral correction of the radiation flux falling onto the receiver. These requirements should be in compliance with the curve of relative spectral light effectiveness V (A) . That is why, the standard light filters and reflecting plates employed for the metrological control of these types of measurements must possess nonselectivity with respect to the spectral composition of radiation falling on them, as well as chemical and light damage resistance, heat resistance and mechanical strength. The sets of the neutral light filters used in the USSR are principally plane-parallel plates made of neutral homogeneous glass having various thickness and sizes. The filters reveal various transmission factors in a range from 0.0 1 to 0.92 and serve to check the photometric scale of devices and instruments.

The paper is devoted to the recent development aimed at effectively correcting the spectral sensitivity of selective and non-selective radiation receivers to conform to the spectral luminous efficiency by using liquid correction filters. The basic principle for stabilizing liquid filters and the methods of optimal component determination with the account of the spectral characteristic of an individual radiation receiver are described. The measurement and calculation results in support of the suggested mathematical model of the transmission function are presented, and the characteristics of the liquid filters currently used in the national primary standard of luminous intensity are specified.

A method of luminous intensity measurement in accordance with the new definition of candela adopted by the 16th International Committee of Weights and Measures in 1979 is described. Principal emphasis is placed in applying selfcalibrated photodiodes to the spectroradiometric measurements. The results of luminous intensity measurements with the CSMU photometric standard lamps are given.

When transmitting energetic units the crux lies in a monochromator-comparator that allows to compare the spectroenergetic characteristics of radiation sources and detectors. For the last decade, the Fourier spectrometers have found a wide application in the world practice of optical and spectral analysis [1, 2]. Thanks to a number of advantages (high sensitivity, wide spectral range, high aperture ratio, accuracy of the wavelength scale, high rate of scanning, high level of automation, etc) , these instruments claim to a leadership in the field of spectral investigations. They deserve the most serious attention in the energetic photometry as well. Since the Fourier spectrometer is based on an interferometer, further we will consider the possible application of these instruments on the basis of an interferometer.

The refraction factor profile (RFP) in a gradient optical fiber light guide determines information channel capacity of a fiber transmission line and should be tested with an error of about 10^-4. Of the greatest interest in RFP studying in half-finished light guide fiber as soon as precise knowledge of the RFP values results in preliminary selection of non- conditions wires before their stretching out, along with opportunity to improve the technology. Transverse interferometry is one of the most precise non-destructive methods for this purpose. Commonly, one uses Mach-Zender interferometer which has unfortunately high vibration sensitivity, that complicates the interferometer adjustment and prevents the user from obtaining high contrast and low noise interferograms. In the present report the Moire method's possibilities to solve the problem are discussed.

A multipurpose automated photometer designed for controlling the sharpness and noise characteristics of photolayers and their spatial homogeneity is described. The photometer's specifications are given and the results are reported of the investigation of the bright strip contrast function and modulation transfer function of undeveloped course- and fine-grain laboratory-cast photographic films in the passed radiation.

A method is reported for estimating thermophysical and optical parameters, in which a two- spectral band sandwich photodetector is used. The sensitivity ranges of such a sensor are 2 - 5 micrometers and 8 - 14 micrometers . On irradiating an object's surface by a short radiation pulse the photodetector collected signals U₁, U₂ and the rates of their changes (dU₁/dt), (dU₂/dt) are recorded. These pertain to the same area on the object's surface and belong to the two spectral ranges mentioned. The parameters of the object are evaluated by means of calculations with the values measured.

A number of devices for residual stress monitoring in glass and other transparent optical media consisting of an illuminator and a registering part are known. Use of these devices makes it impossible to determine the residual inner stress in a transparent sample, the back side of which is covered with a mirror reflecting coating. The device we propose is able to make the final testing. The new instrument allows us to measure the residual stress either in samples that are transparent for probing radiation or in transparent for probing radiation objects, the rear side of which are covered with the reflecting coating. It is achieved in the following way: at a measuring residual stress in reflecting objects the recording part of the device may be located in the same half-space with the illuminator and receiver the radiation, reflected by the coating.

Problems of accuracy and sensitivity of polarimetry are discussed. Optimization method of measurements under the classical quenching scheme is proposed, results of theoretical estimations and experimental verification are presented.

The practice of using multichannel scanning systems and videospectrometers has shown the presence of a problem of information redundancy as well as the presence of a problem of increasing the accuracy and operativeness of identification, especially for objects with small changes in spectral characteristics. Agricultural crops and soils as the objects of monitoring are characterized by large accidental changeability of the spectral properties in space and time, that results in the identification accuracy errors of up to 15 - 20%. At the same time, the present task of nature management requires a realization of the ecological monitoring of agricultural biogeosystems with the aim of checking and controlling. This requires an improvement of the quality of optical remote information and new information technologies of its processing, enabling early detection, localization and identification of sowing of the soils and agricultural crops, evaluation of their provision with the elements of mineral nutrition. In this case, it is necessary to exclude to a maximum extent the influence of various natural and technical factors (NTF) , distorting the information obtained by remote methods.

Results of different researches [1, 2, 31 , prove that the whiteness as any other color is fully defined by three-color coordinates. Anyhow, the introduction of the colorimetric methods is hindered by some old tradition and inertia which limit the estimation of the whiteness by one figure, as well as the by the tendency to have a simple one-dimensional scale. In this case, there are no one opinion and consent as to one universal formula for estimation of the whiteness since the universal conception of the whiteness is like not to exist [1 ,4, 5] . Depending on the kind of the products to be checked for whitenessproduction, provision is made for its own ideal white color.That is why for each kind of products (paper, cellulose, textile, ceramics, while paint, porcelain, steel sheets etc.) , use should be made of the various methods preliminary based on the colorimetric researches taking into account their comparability with the visual estimations. In some cases, as the colorimetric experiments show [ 1 ], it is really possible to estimate the whiteness by using the simplified methods employing two coordinates (y -albedo z - blueing) and even one three-color coordinate. For example, during manufacturing such materials as paper, cardboard, cellulose and textile, the quality of these materials is checked for whiteness only in blue range of the spectrum. This method of whiteness estimation is controlled by the domestic and international standards [6-9].

A spectrocolorimetric complex for measuring the color coordinates of non-selfluminous objects was developed in our Institute as a part of a new standard color complex which is used as a state calibration test system for color and chromaticity coordinates measurement facilities instead of the previous one. The basic result of the present work is the reproduction and transfer of the unit dimension against the absolute scale of the color coordinates carried out within the framework of the entire calibration test system for the first time.

The results of subjective numerical ranking of color photographic prints deterioration after storage, carried out by groups of professionally experienced observes and unexperienced amateurs, were compared with results of objective measurements of color shift expressed in NBS units. A number of regularities were established, these depending on color hues examined. As a whole, a large degree of correlation between two approaches to color evaluation has been demonstrated.

The densitometric approach to integral shifts in color photographic images upon dark storage in various conditions and the colorimetric approach to color hue shifts in the same images were shown to be non-coinciding in Arrhenius-based predictions of image permanence. This is shown to be no argument for or against any of the two approaches, but merely results from principally different information content involved in data obtained in each approach. The predictions are always more short-termed for images becoming unsatisfactory by color mismatching than those for their integral decay. Both modes of predictions, as compared with direct experiment whenever possible, seem to give reasonable data.

The main parameters determined by colour picture tube manufactu— rers are brightness and the ratio of anode currents of electron beams at white luminescence of the screen I I . To determine there parameters it is necessary to set the white colour of the luminescence and to measure the brightness of the white field luminescence, as well as the total anode current of electron gun and anode current for every beam. it is especially important to determine with the utmost accuracy the white colour of the screen luminescence, as it is known that set— ting of two different white colours with colour temperatures of 6500 K =O.3i3. v=O.329' and 9300 H (x=O28i. v=0.31fl on the same colour picture tube, operating under a certain mode at the same total anode current of electron gun, gives rise to changes in the screen lumines cence brightness up to several per cents, x and y being the chrornacity coordinates of the system XYZ as per 1931 CIE Standards.

The necessity for illuminance measurement arises when solving a number of problems -- in photometry, thermal physics, biology, meteorology, agriculture, everyday and industrial sanitation when developing cine, photographic and video technique, illuminating equipment, etc. The instrument described below was developed for illuminance measurement by studying photometric characteristics of natural formations from the aircraft.

To estimate accurately energetic luminance (EL) of objects for determination of their optical properties it is necessary to know the error of measurement mean -- that is radiometer error. Using the multichannel radiometers with several spectral ranges allows us to increase the reliability of the results, but it creates some difficulties during the graduating with external reference radiators. With large distance between the spread of spectrum bands, for example from the middle wavelengths to the long wavelength, the requirements to a range and stability of EL reproduction by external reference radiators become individual for every channel.

Half-tone images, obtained at photographic registration of fast events, are photometered by a scanning microdensitometer. Usually such an instrument has a mechanical scanner and a single-channel photometering head. We examined metrological performances of a new scanner that reduces considerably the time needed for photometering, which results from the use of an electronic scanning along one of the coordinates.

When analyzing curves of intensity decay in pulse photometry of optical radiation, the problem of estimation of unknown parameters of the decay function representable as a sum of exponents Ii 1(t) = A1 exp (— t/t1), i=l (1) where A - amplitudes, rj - decay times, i = 1 , . . . , n, arises. It is rather complicated to carry out such studies because in the majority of cases recorded time responses are in the nanosecond interval of duration. The last requires to take into account the influence of imperfect characteristics of recording equipment, which leads to the necessity of solving integral equations of the convolution type

Design of means for measuring optical radiation power of small levels (below i05 W) has come into an active phase in the '80s thanks to a fast development of fiber optical transmission systems (FOTS) . Atfirst, all manufacturers producing this kind of measurement means have calibrated them at their own laboratory facilities. This has led to a good deal of discrepancy in measurement results which became evident in the very first comparison studies' .Toavoid the discrepancy that could lead to dramatic consequences up to a total mismatch of fiber optical systems, special neasurement standards have been suggested and appropriate hardware has been designed to reproduce and transmit the power unit. The transmission of the power unit may be affected in most different ways. Techniques used initially for this purpose were traditional for non coherent radiometry. In our country, the transmission of the power unit is carried out by a multistage technique crowned by a primary State Standard for the average power of laser radiation of medium level. The leading world companies in the USA, Germany and Japan obtain the power unit value from primary standards of radiation of small levels.

Characteristics of various photorecording equipment (photometers, image sensors, laser radiation analyzers, laser communication, detection, ranging and other systems) are determined mainly by parameters of photoreceiving devices (PhRD) used. The present communication gives results of theoretical and experimental studies of a number of new PhRD circuits.

This work presents the results of studying the shock wave radiator made of a quartz microsphere filled in with neon at a pressure of 15 atm (the envelope diameter: 175 micrometers , thickness: 1.5 micrometers ), connected to the OKMB type quartz light guide, referred to as a `light pen' (LP). The LP transducers have been developed by us for optical recording of shock and detonation waves in a nanosecond range. The shock wave movement through neon in the microsphere is accompanied by radiation of light, which is transmitted via the light guide to a photorecorder.

A method for photodetectors quantum efficiency determination based upon a photocurrent fluctuations analysis at a priori defined radiation field statistics is presented. The value of quantum efficiency of silicon photodiode at the radiation wavelengths 0.67 and 0.95 micrometers is obtained experimentally.

A device for duration measurements of the picosecond and subpicosecond optical pulses in single shot is described. The elaborated scheme allows us to measure autocorrelation trace in a dynamic range no less than 10³. Operation is demonstrated by investigation of the temporal properties of the optical pulse on the output of the mode-locked Nd:glass laser.