Cassegrain telescope

The standard 0.75 M Spectraspan III has an approximately 6 cm x 7.5 cm display. Since the CID used is only 1.1 x 0.85 cm, only a very small portion of this display could be observed at any one time. However, this problem has been recently reduced by substituting a 15 cm focal length, f/1.4 Schmidt corrected Cassegrain telescope (Nye Optical, Spring Valley, CA) for the camera mirror (Figure 3). This reduces the display dimensions five fold. The focal plane remains flat and a minimum resolution of 0.1 nM is achieved. With this optical system the entire 200 to 800 nM region cannot be viewed simultaneously. Further image reduction is possible, but resolution will be compromised... 

M2IM1 Cassegrain telescope mirrors - 0D 215 I 0dl2 mm telescope length is 640 mm ... 

The angular (spatial) resolution of a telescope, or of any optical system, is ultimately limited by diffraction. As an example, we calculate these limitations for an instrument with a Cassegrain telescope however, the theory is directly applicable to other configurations as well. 

Figure 10.23. Geometry of different focusing systems and detector positions with parabolic radio telescope reflector dishes, (a) Cassegrain, (b) Gregory, (c) Nasmyth, (d) offset Cassegrain [36]. 

We have made a modest effort to use ANN for parametrization of a sample of stars in the temperature range 4500 to 8000 K. We have used a medium resolution Cassegrain spectrograph with the 2.3 m Vainu Bappu Telescope at VBO, Kavalur, India to get spectra at resolution (R) of 2000. Using 90 spectra for stars of known parameters, and ANN of 680 11 3 architecture we could attain an accuracy of 200 K in temperature and 0.3 dex in metallicity. 

In [9] it was shown that instrumental polarization for the polarimeter installed at the 60-cm telescope of the observatory near Tarija (Bolivia), had statistical error 0.024 % and the mean square was 0.023%. Investigations have shown that instrumental polarization in Newton and Nesmith focus can reach 5%, whereas it is less than 0.05% in a well adjusted Cassegrain. In the former case, values of Pi increase with wavelength whereas they decrease in the latter. 

Figure4.8 shows the collecting telescopes configuration. Each consists of a pair of focal parabolas (primary Ml, secondary M2) used in a Cassegrain configuration, plus a fold flat used for coarse beam steering (M3). The design is based in NASA s SPIRIT proposal (Wilson et al. 2007). After the beam steering mirror the light is...

The telescope used, a MEADE ETX-125 Maksutov-Cassegrain, 125 mm clear aperture, 1900 mm focal length,//15, was coupled to the Raman spectrometer with a non-imaging optical fiber bundle (600 pm diameter, model AL 1217, Ocean Optics, Inc.) containing the appropriate filters for the rejection of the... 

The mirror optics for large telescopes, which were developed later on by Cassegrain, utilized a large concave primary mirror which collects as much... 

We have used the RockweU Nicmos 3 infrared array camera described in Persson et al (1992) at the Cassegrain focus of the 40—indi Swope telescope at the Las Campanas Observatory in ChUe for 5 nights in June 1992. This... 

The telescope is a 3 mirror bent Cassegrain design. It feeds GRIM mth an f/10 beam to match the constraints set by the internal reimaging optics of the instrument. The telescope padcage is 27 inches in overall diameter and 56 inches long. 

The optical design of the spectrometer is presented in fig.l The 1ms B is a field lens. The mirrors D and E are a Cassegrain system (f/20) that collimates the optical beam coming from the telescope. The coUimated beam is reflected on the grating G by the plane mirror F. Finally the camera of the spectrometer (mirrors H and I), focalize the radiation on the detector L. 

These measurements were carried out over the period 1992 February to 1993 July at the Hale 5-m telescope with the same camera used for the survey initially with the f/415 G egori ul secondary and later on (after 1993 May) with a new reimaging systems designed to go with the standetrd f/70 Cassegrain secondary. Additional observations were made at the Steward Observatory 90 with a similar two-dimensional speckle imaging camera described by McCarthy et aL (1990). 

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