scholarly journals PbS and CCD Array Autocollimation Micrometers for the Infrared Meridian Circle

1995 ◽  
Vol 167 ◽  
pp. 337-338
Author(s):  
V. N. Yershov
Keyword(s):  
Focal Plane ◽  
Optical Axis ◽  
Meridian Circle ◽  
Pulkovo Observatory ◽  
Primary Mirror ◽  
Small Constant ◽  
Ccd Array ◽  
Secondary Mirror ◽  
Axis Position ◽  
Optical Unit

A new infrared meridian instrument is being developed at Pulkovo Observatory. The main purpose of the instrument is to extend the fundamental coordinate system to the K-infrared waveband and to faint stars at visual and I-wavebands. The instrument has a 30-cm primary mirror made from astrositall. An intermediate focal plane is used to introduce luminous reference marks. One can obtain autocollimated images of the marks at the intermediate focal plane with the use of a polished chamber located around the central hole of the primary mirror. The secondary mirror of the telescope forms images of the marks and of their autocollimated counterparts and passes them to the plane of a photodetector (Fig. 1.). The luminous marks give a reference frame for the measurements. These measurements are not affected by displacements of any optical unit placed after the intermediate focal plane or by displacements of the detector. The measurements are done relative to the coordinates of the average between positions of the luminous mark and its autocollimated image. Any small constant difference between the center of curvature and the optical axis position can be determined in the laboratory.

scholarly journals A Giant Meridian Circle - Reflector

1995 ◽  
Vol 166 ◽  
pp. 360-360
Author(s):  
V.N. Yershov
Keyword(s):  
Focal Plane ◽  
Optical Axis ◽  
Focal Length ◽  
Vertical Plane ◽  
Optical Scheme ◽  
Infrared Observations ◽  
Secondary Mirror ◽  
Axis Position ◽  
Reference Grid ◽  
Reading System

A 1.5 m reflector is proposed for infrared and optical meridian observations in order to extend the fundamental coordinate system to faintest objects and to the K-infrared waveband. Classical meridian circles are unfit for the infrared observations because their lens objectives do not give good images in the infrared. But reflectors are almost never used as meridian circles due to uncertainties in their optical axis position. The main problem is that the secondary mirror is not connected with the micrometer and the circle reading system. In order to overcome this difficulty the author proposes to use an intermediary focal plane between the primary and the secondary mirrors where a luminous reference grid of wires might be placed. The Gregory optical scheme has such a focal plane, and its secondary mirror forms images of a star and the grid at the micrometer's detecting area. At the same time a special champher around the primary's central hole forms anautocollimated image of the grid near the grid itself. The micrometer measures the star image coordinates relative to two images of the reference grid. So, observations will not be affected by displacements of the secondary mirror and by those of the micrometer. The telescope's equivalent focal length has been chosen as 3 m, and the optical system has been transformed into an aplanatic Mersenne combined with an aplanatic focal reducer corrector (Popov, 1988). A new autocollimated circle reading system is chosen for the instrument (Yershov and Nemiro, 1994). The observations will be linked to the fixed optical axis of two long-focus collimators placed at the prime vertical plane.

scholarly journals An Autocollimation Circle Reading System for the Infrared Meridian Instrument

1995 ◽  
Vol 166 ◽  
pp. 361-361
Author(s):  
V.N. Yershov ◽  
A.A. Nemiro
Keyword(s):  
Optical Axis ◽  
Angular Position ◽  
Optical Center ◽  
Meridian Circle ◽  
Primary Mirror ◽  
Axis Position ◽  
Spherical Mirrors ◽  
Reading System ◽  
Zero Points ◽  
New System

A new autocollimation circle reading system is proposed for the reflector meridian circle (Nemiro and Streletsky, 1988). The instrument will be used for observations in the K-infrared waveband. Instead of the divided circle fixed to the instrument tube the new system has small spherical mirrors polished at the lateral surfaces of the primary mirror. The primary mirror is made from sitall and has an autocollimation system aimed at monitoring its optical axis position. The small spherical mirrors of the circle reading system link the circle readings with the primary's optical axis. The divided circles are fixed unmovable opposite to both lateral surfaces of the primary's optical block. Both surfaces have four spherical mirrors. The distance between the divided circles and the mirrors is equal to the mirrors' radii of curvature. The scales of each circle are illuminated from outside (where the measuring microscopes are placed). The mirrors form autocollimated images of the divisions at the plane of the divisions itself. Averaged coordinates of a division and its autocollimated image give the position of the mirror's optical center, and the semi-difference of the coordinates gives the angular position of the telescope. So, the measurements of the circle positions are differential ones, and any displacements of the microscope zero-points are not critical. The precision of measurements is estimated to be better then 0.05″ (random) and 0.005″ (systematical). The work was supported by the Russian Foundation of Fundamental Investigations (the project's code is 93-02-17095).

scholarly journals The Modernization of the Pulkovo Photographic (Photoelectric) Vertical Circle by a CCD Array

1995 ◽  
Vol 167 ◽  
pp. 333-334
Author(s):  
G. A. Goncharov ◽  
B. K. Bagildinsky ◽  
E. V. Kornilov ◽  
D. D. Polojentsev ◽  
K. V. Rumyantsev ◽  
...  
Keyword(s):  
Focal Plane ◽  
Focal Length ◽  
Wide Field ◽  
List Type ◽  
Type Number ◽  
Pulkovo Observatory ◽  
Vertical Circle ◽  
Ccd Array ◽  
Field Imaging ◽  
Wide Field Imaging

The Zverev photographic vertical circle (PVC) of the Pulkovo observatory is in the process of modernization. The features of the vertical circle are: a)Maksutov mirror-lens optical system with small aberrations and wide passband: aperture: 20 cm, focal length: 200 cm, focal scale: 103 arcsec/mm.b)Very compact instrument: 140 cm total length, 60 cm — tube.c)Wide field: 25 × 25 mm = 40′ × 40′. Wide-field imaging can be combined with meridian observations.d)Easily-reversible instrument: reversing takes less than 30 seconds.e)Two divided vertical circles of glass. Photoelectric circle reading microscopes.f)Photographic micrometer in focal plane. This will be changed with a CCD micrometer.

scholarly journals 8. Positional Astronomy

1970 ◽  
Vol 14 (1) ◽  
pp. 39-51
Author(s):  
A. A. Nemiro ◽  
W. Fricke ◽  
A. N. Adams ◽  
P. Lacroute ◽  
R. H. Stoy ◽  
...  
Keyword(s):  
Meridian Circle ◽  
New Materials ◽  
Digital Readout ◽  
New Techniques ◽  
Primary Mirror ◽  
Astronomical Instruments ◽  
Large Numbers ◽  
On Line ◽  
Positional Astronomy ◽  
And Control

It is with deep regret that we mention the death, on 15 July 1969, of Prof. Dr G. Demetrescu who has done so much for the development of Astronomy in Roumania.This report is based on letters received from members of the Commission, whom I wish to thank most cordially.The most important events in the development of positional astronomy during the three past years were:(1)The construction and use of new types of astronomical instruments based on new techniques, and(2)The collective observations of large numbers of stars, especially in the Southern hemisphere on the basis of international cooperation.At the USNO a design study for a ten-inch automatic meridian circle (ATC)was completed in 1968. Construction and installation should be completed by the end of 1970. A modified Cassegrainian optical system with a Cer-Vit primary mirror is being used. For some other important parts of the instrument new materials will also be used. At each end of the horizontal axis of the instrument Inductosyns will be mounted.An Inductosyn system for digital readout of the pointing angle of the telescope was installed on the six-inch transit circle of the USNO in 1967 for testing and calibration. An IBM-1800 data acquisition and control system was on line with the same instrument.

Design and analysis of supporting structure between the primary mirror and the secondary mirror on a space telescope

2015 ◽  
Author(s):  
Chenjie Wang ◽  
Wenyi Chai ◽  
Liangjie Feng ◽  
Wengang Yang ◽  
Wei Wang ◽  
...  
Keyword(s):  
Space Telescope ◽  
Primary Mirror ◽  
Supporting Structure ◽  
Secondary Mirror

The eye of the soldier beetle Chauliognathus pulchellus (Cantharidae)

1979 ◽  
Vol 203 (1153) ◽  
pp. 361-378 ◽  
Keyword(s):  
Cross Section ◽  
Focal Plane ◽  
Optical Axis ◽  
Field Size ◽  
Acceptance Angle ◽  
Corneal Surface ◽  
Physiological Properties ◽  
Cone Cells ◽  
Optical Pathway ◽  
Surface Calculation

The soldier beetle eye is unusual in having large optically isotropic corneal cones which project inwards from a thick isotropic cornea. Refraction is mainly at the corneal surface. Calculation shows that the first focal plane is near the tip of the cone, from which the optical pathway continues as a crystalline tract. At the distal end of the crystalline tract, 3 µm in diameter, the four cone cells enclose the proximal tip of the corneal cone; at the proximal end they enclose the distal tip of a long fused rhabdom rod. The eye is remarkable in that there are two classes of retinula cells; four cells contribute to the long thin axial rhabdom, 2 µm in diameter and 120 µm long, and the other four cells form two rounded rhabdoms, 10 x 4 µm in cross-section and 20 µm deep, which lie to one side of the optical axis. The physiological properties of individual retinula cells were measured by intracellular recording. The retinula cells are of three spectral types with peaks near 360, 450 and 520–530 nm. Except by the criterion of spectral sensitivity, the retinula cells sampled could not be sorted into more than one class. The measured value of the acceptance angle, near 3° in the dark-adapted state, is consistent with the hypothesis that all sampled cells were of the anatomical type that participate in the central rhabdom rod. A calculation of the theoretical field size of individual retinula cells from measurements of refractive index and lens dimensions predicts that cells which participate in the central rhabdom will have acceptance angles near 3°. The conclusion, therefore, is that only one anatomical type of cell has so far been sampled.

scholarly journals SPHERICAL PRIMARY MIRROR IN TELESCOPES WITH COMPLEX (MULTI-ELEMENT) OPTICAL DESIGNS

2021 ◽  
Vol 34 ◽  
pp. 81-84
Author(s):  
S.V. Podlesnyak ◽  
N.N. Fashchevsky ◽  
Yu.N. Bondarenko ◽  
S.M. Andrievsky
Keyword(s):  
Wave Front ◽  
Focal Plane ◽  
Optical Design ◽  
Effective Field ◽  
Field Of View ◽  
Spherical Mirror ◽  
Primary Mirror ◽  
Reflected Wave ◽  
Aperture Ratio

An optical design for telescope with spherical primary mirror, planoidal surface and two-lens corrector is discussed. The spherical mirror hasn aperture ratio 1/2.69. After reflection from the spherical mirror, the wave front falls on a planoidal surface and “forms” the reflected wave front from a virtual mirror with e 2 = 1.576. After passing the two-lens corrector, the light is collected in the focal plane. A dot diagram in the focal plane shows that all three-order aberrations are successfully corrected. The effective field of view is 2 degrees. The aperture ratio is 1/2.28.

scholarly journals Commission 8. (Meridian Astronomy.)

1933 ◽  
Vol 4 ◽  
pp. 225-226
Author(s):  
Frank Dyson ◽  
J. H. Oort
Keyword(s):  
Southern Hemisphere ◽  
Special Interest ◽  
Variable Stars ◽  
Meridian Circle ◽  
Pulkovo Observatory ◽  
Southern Latitude ◽  
Financial Conditions ◽  
Vertical Circle ◽  
Short Period ◽  
Emission Stars

In connection with the plans of the Pulkovo Observatory for removing one of their vertical circles to the southern hemisphere the following recommendation was proposed by Dr Morgan and seconded by Prof. Boss: “The Commission regards the proposal of the Pulkovo Observatory to establish the Vertical Circle in as nearly equal a southern latitude as possible with great sympathy. We believe this will be of very great value in the improvement of fundamental decimations.”Dr Lundmark read a report on the programmes for the Lund meridian circle, which programmes include stars of special interest, such as long- and short-period variables, extremely red non-variable stars, B-emission stars, moving clusters, nebulous stars, nuclei of planetary nebulae and of anagalactic objects, etc. The definite programme will contain at least 3000 stars, results for some 400 of which have already been obtained. It is planned to extend the observations to stars in the southern hemisphere as soon as financial conditions will permit the erection of a southern station.

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