Pub Date : 1976-11-01DOI: 10.1088/0335-7368/7/6/305
M. Belmahdi
The building of large flux collectors for infrared astronomy necessitates the construction of mirrors less precise than those of conventional telescopes (the optical quality is restricted to a value which takes into consideration, in particular, the dimensions of the detector that is used and of the collector itself). We are trying to make mirrors with new designs, light and less costly. With this aim, a prototype of hexagonal element, 98 cm across, of a primary mosaic of a projected collector of large diameter, was built, tested and polished. We give the description of the mirror and details of the making. The weight reduction of the mirror to 70 per cent and the optical quality obtained will allow the effective utilisation of this new mirror.
{"title":"An economical construction of large astronomical lightweight mirrors made of glass","authors":"M. Belmahdi","doi":"10.1088/0335-7368/7/6/305","DOIUrl":"https://doi.org/10.1088/0335-7368/7/6/305","url":null,"abstract":"The building of large flux collectors for infrared astronomy necessitates the construction of mirrors less precise than those of conventional telescopes (the optical quality is restricted to a value which takes into consideration, in particular, the dimensions of the detector that is used and of the collector itself). We are trying to make mirrors with new designs, light and less costly. With this aim, a prototype of hexagonal element, 98 cm across, of a primary mosaic of a projected collector of large diameter, was built, tested and polished. We give the description of the mirror and details of the making. The weight reduction of the mirror to 70 per cent and the optical quality obtained will allow the effective utilisation of this new mirror.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132420625","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-11-01DOI: 10.1088/0335-7368/7/6/304
R. Pasquetti, F. Papini
This study is concerned with the design of a selective surface, in view of its possible utilization in the range of medium temperature solar energy thermal conversion (between 80 and 200 °C). The study of significant parameters (absorption and emission factors, cut-off wavelenth,...) allows the determination of optical properties for such a surface. It is so demonstrated that a hot selective surface shows a good interest for helio-thermal conversion at medium range temperature. A two thin layers selective structure on a metallic substrate is then determined: Lead sulfide and zinc sulfide deposition on to aluminium substrate leads to convenient theoretical results, that are experimentally confirmed. Moreover, replacement of aluminium by zinc or nickel seems to be encouraging. Generally an absorption factor of 80% is obtained, together with a 6% global hemispherical emissivity value at 200 °C. Durability tests as a function of temperature showned significant results.
{"title":"Study and realization of a selective surface for thermal conversion of solar energy: application to medium range temperature","authors":"R. Pasquetti, F. Papini","doi":"10.1088/0335-7368/7/6/304","DOIUrl":"https://doi.org/10.1088/0335-7368/7/6/304","url":null,"abstract":"This study is concerned with the design of a selective surface, in view of its possible utilization in the range of medium temperature solar energy thermal conversion (between 80 and 200 °C). The study of significant parameters (absorption and emission factors, cut-off wavelenth,...) allows the determination of optical properties for such a surface. It is so demonstrated that a hot selective surface shows a good interest for helio-thermal conversion at medium range temperature. A two thin layers selective structure on a metallic substrate is then determined: Lead sulfide and zinc sulfide deposition on to aluminium substrate leads to convenient theoretical results, that are experimentally confirmed. Moreover, replacement of aluminium by zinc or nickel seems to be encouraging. Generally an absorption factor of 80% is obtained, together with a 6% global hemispherical emissivity value at 200 °C. Durability tests as a function of temperature showned significant results.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123255241","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-11-01DOI: 10.1088/0335-7368/7/6/302
P. Cahuzac, G. Golman
We propose here an experimental set-up allowing a precise measurement of mirror reflectances close to unity. The experimental arrangement is easy to adjust, although it requires the use of multi-paths optical cavity. The method can be applied to spherical mirrors as well as flat ones. The accuracy is up to 5.10−4. Results of measurements for visible and infrared spectral ranges are presented.
{"title":"Measurement of high reflectances by use of multi-paths optical cavity","authors":"P. Cahuzac, G. Golman","doi":"10.1088/0335-7368/7/6/302","DOIUrl":"https://doi.org/10.1088/0335-7368/7/6/302","url":null,"abstract":"We propose here an experimental set-up allowing a precise measurement of mirror reflectances close to unity. The experimental arrangement is easy to adjust, although it requires the use of multi-paths optical cavity. The method can be applied to spherical mirrors as well as flat ones. The accuracy is up to 5.10−4. Results of measurements for visible and infrared spectral ranges are presented.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130859497","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-11-01DOI: 10.1088/0335-7368/7/6/301
E. Pelletier, P. Roche, B. Vidal
We briefly describe the principle of a completely automatic spectrophotometer which measures optical properties (R, R', T) in the spectral range 2 000-7 000 A. The results obtained for normal incidence are then used by computer to determine the optical constants (n, k) and thickness d of a thin film. We study in detail the computer program which is based on successive iterations. The parameters d, n, k must be successively determined. First iterations are performed to compute thickness and mean values of n and k over a large spectral range. It remains to determine the complex refractive index, the accuracy being only limited by experimental errors measurements. We present some of our results. For certain layers, the curve n(λ) obtained shows characteristic discontinuities and we conclude that the layer has defects of structure. On the other hand, it is possible to obtain practically perfect layers with given materials and with the values of optical constants differing little from one layer to another if evaporation conditions are identical.
本文简要介绍了一种全自动分光光度计的原理，该分光光度计可测量光谱范围为2 000-7 000 a的光学性质(R, R′，T)。然后用计算机计算法向入射的结果来确定薄膜的光学常数(n, k)和厚度d。对基于连续迭代的计算机程序进行了详细的研究。参数d, n, k必须依次确定。第一次迭代执行计算厚度和平均值n和k在一个大的光谱范围内。复折射率的测定还有待进一步研究，其精度仅受实验误差测量的限制。我们将介绍我们的一些结果。对于某些层，得到的曲线n(λ)显示出特征不连续，可以得出层存在结构缺陷的结论。另一方面，如果蒸发条件相同，则有可能用给定的材料获得几乎完美的层，并且层与层之间的光学常数值相差不大。
{"title":"Automatic evaluation of optical constants and thickness of thin films: application to thin dielectric layers","authors":"E. Pelletier, P. Roche, B. Vidal","doi":"10.1088/0335-7368/7/6/301","DOIUrl":"https://doi.org/10.1088/0335-7368/7/6/301","url":null,"abstract":"We briefly describe the principle of a completely automatic spectrophotometer which measures optical properties (R, R', T) in the spectral range 2 000-7 000 A. The results obtained for normal incidence are then used by computer to determine the optical constants (n, k) and thickness d of a thin film. We study in detail the computer program which is based on successive iterations. The parameters d, n, k must be successively determined. First iterations are performed to compute thickness and mean values of n and k over a large spectral range. It remains to determine the complex refractive index, the accuracy being only limited by experimental errors measurements. We present some of our results. For certain layers, the curve n(λ) obtained shows characteristic discontinuities and we conclude that the layer has defects of structure. On the other hand, it is possible to obtain practically perfect layers with given materials and with the values of optical constants differing little from one layer to another if evaporation conditions are identical.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"45 6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123128179","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-11-01DOI: 10.1088/0335-7368/7/6/306
G. Lemaitre
The theory of elasticity is applied to the determination of the flexure of telescope secondary mirrors in the field of gravity. With respect to the basic configuration defined by a mirror of essentially constant thickness, we consider the thickness profile to be a free parameter. As a first approach to the problem, we study four thickness configurations supported by their central zone, and having the same total mass. The sharp edge lenticula configuration leads to Euler-Gauss hypergeometrical functions. The quasi-conical configuration is that which gives ideal rigidity since its own deformations, purely parabolic, do not result in any image quality degradation. The configuration permitting one to aspherize the mirror by the dioptric elasticity method also represents a considerable gain in rigidity compared to the basic configuration.
{"title":"On the flexure of telescope secondary mirrors","authors":"G. Lemaitre","doi":"10.1088/0335-7368/7/6/306","DOIUrl":"https://doi.org/10.1088/0335-7368/7/6/306","url":null,"abstract":"The theory of elasticity is applied to the determination of the flexure of telescope secondary mirrors in the field of gravity. With respect to the basic configuration defined by a mirror of essentially constant thickness, we consider the thickness profile to be a free parameter. As a first approach to the problem, we study four thickness configurations supported by their central zone, and having the same total mass. The sharp edge lenticula configuration leads to Euler-Gauss hypergeometrical functions. The quasi-conical configuration is that which gives ideal rigidity since its own deformations, purely parabolic, do not result in any image quality degradation. The configuration permitting one to aspherize the mirror by the dioptric elasticity method also represents a considerable gain in rigidity compared to the basic configuration.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123996388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-11-01DOI: 10.1088/0335-7368/7/6/303
P. Gallet, A. Ropke
Anti-losses cellular structures are a device allowing the reduction of radiative losses existing in solar absorbers by modification of radiative transfers upon the collecting surface. This device is composed of prismatic cells, normal to the surface to be protected which so constitute the base of the cells. To study anti-radiative properties of such devices, it is necessary to determine the emittance distribution along the walls of one cell. The works done until now were concerned with black or diffuse grey surfaces, in the field of far infrared (λ > 3 μm). Having given the results relative to both these types of surfaces, the authors are presenting in this paper a method for determination of emittance distribution along a cell walls, whatever being the shape of emission index for far infrared, and the reflection on to the surface being only a specular one. Then, the method is applied to two special situations in which the index is ellipsoidal.
{"title":"The study of emittance distribution along the walls of a cellular anti-losses structure, associated to a base surface whatever being the index emission shape","authors":"P. Gallet, A. Ropke","doi":"10.1088/0335-7368/7/6/303","DOIUrl":"https://doi.org/10.1088/0335-7368/7/6/303","url":null,"abstract":"Anti-losses cellular structures are a device allowing the reduction of radiative losses existing in solar absorbers by modification of radiative transfers upon the collecting surface. This device is composed of prismatic cells, normal to the surface to be protected which so constitute the base of the cells. To study anti-radiative properties of such devices, it is necessary to determine the emittance distribution along the walls of one cell. The works done until now were concerned with black or diffuse grey surfaces, in the field of far infrared (λ > 3 μm). Having given the results relative to both these types of surfaces, the authors are presenting in this paper a method for determination of emittance distribution along a cell walls, whatever being the shape of emission index for far infrared, and the reflection on to the surface being only a specular one. Then, the method is applied to two special situations in which the index is ellipsoidal.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128835525","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-09-01DOI: 10.1088/0335-7368/7/5/302
J. Bescós, J. Santamaría
The colour distribution in the Polychromatic Line Spread Function is computed in the case of primary aberrations. Different corrections of longitudinal and transverse chromatism, constant and dispersive cases of spherical aberration, coma and astigmatism have been considered. The calculations have been carried out for source C, and the standard observer, specified by the three sensitivity functions of the human eye CIE 1931.
{"title":"Distribution of colour in the polychromatic line spread function. Influence of the aberrations","authors":"J. Bescós, J. Santamaría","doi":"10.1088/0335-7368/7/5/302","DOIUrl":"https://doi.org/10.1088/0335-7368/7/5/302","url":null,"abstract":"The colour distribution in the Polychromatic Line Spread Function is computed in the case of primary aberrations. Different corrections of longitudinal and transverse chromatism, constant and dispersive cases of spherical aberration, coma and astigmatism have been considered. The calculations have been carried out for source C, and the standard observer, specified by the three sensitivity functions of the human eye CIE 1931.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"178 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123344014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-09-01DOI: 10.1088/0335-7368/7/5/303
G. Agrawal
An object illuminated with partially coherent light is imaged through a square law medium characterized by the dielectric variation (r, z) = 0(1 - α2 r2). We have studied the performance of this medium as an imaging element. An expression for the intensity distribution at the observation plane is derived and is found to be formally identical to the homogenous case. This formal identity is used to obtain an expression for the optical transfer function in the incoherent case. The variation of the degree of coherence at the observation plane is also considered in a special case when the object is incoherently illuminated.
{"title":"Imaging characteristics of square law media","authors":"G. Agrawal","doi":"10.1088/0335-7368/7/5/303","DOIUrl":"https://doi.org/10.1088/0335-7368/7/5/303","url":null,"abstract":"An object illuminated with partially coherent light is imaged through a square law medium characterized by the dielectric variation (r, z) = 0(1 - α2 r2). We have studied the performance of this medium as an imaging element. An expression for the intensity distribution at the observation plane is derived and is found to be formally identical to the homogenous case. This formal identity is used to obtain an expression for the optical transfer function in the incoherent case. The variation of the degree of coherence at the observation plane is also considered in a special case when the object is incoherently illuminated.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114579466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1976-09-01DOI: 10.1088/0335-7368/7/5/306
M. Arsalane, A. Tosser
Photovoltaic phenomena similar to phototransition effects are induced in ZnS sputtered films by light of energy beneath the band-gap (not more than 0.22 eV). It is advanced that hot electron may escape from the photoionized coulombic centre and moves to some level within shallow traps distribution. Thickness dependent phenomena confirm the existence of a critical thickness in which the density of coulombic centres is higher.
{"title":"Interband photoconduction edge in zinc sulphide thin films","authors":"M. Arsalane, A. Tosser","doi":"10.1088/0335-7368/7/5/306","DOIUrl":"https://doi.org/10.1088/0335-7368/7/5/306","url":null,"abstract":"Photovoltaic phenomena similar to phototransition effects are induced in ZnS sputtered films by light of energy beneath the band-gap (not more than 0.22 eV). It is advanced that hot electron may escape from the photoionized coulombic centre and moves to some level within shallow traps distribution. Thickness dependent phenomena confirm the existence of a critical thickness in which the density of coulombic centres is higher.","PeriodicalId":286899,"journal":{"name":"Nouvelle Revue D'optique","volume":"86 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1976-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122676227","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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