It is provided with rack & pinion arrangement and slit.Slit is of circular type.The jaws of the slit are optically ground.It is provided with Holfmann’s Diaphragm.
It is provided with rack & pinion arrangement for proper focussing of spectral lines.
Eyepiece ; (Ramsden Type) : magnification : 10x
In eyepiece holder a conical pointer is fitted in the focal plane of eyepiece.
(c) Corrected achromatic doublet are fitted in the lens holders of collimator and telescope tube.
Doublet dia : 44mm, F.L. : 350mm (14").
(d) A calibrated drum (Calibration for visible region i.e. from 4000A°- 7000A°) is attached with the prism table assembly. Accuracy of calibration + 5A°.
(e) Machined cast iron plate with drum assembly is fitted over the head of a heavy cast iron base.
The base and machined cast iron plate,Collimator, Telescope, Prism table, Drum assembly are painted black.
The Collimator and telescope tubes are fitted in cast iron blocks which are mounted on a machined cast iron blocks which in turn are mounted on a machined cast iron plate.
(f) Suitable gap is provided between collimating lens and prism table to accommodate high resolving instrument like Fabry-Perot Etalon( to be asked extra).
(g) Prism Table is fitted on the machined cast iron plate and actuated by tangent screw to provide smooth rotation of the C.D.S. prism placed on it.
(h) Prism table is covered with a box of a aluminium casting having two gates. One gate allows light coming from collimator to enter into C.D.S. Prism.Another gate allows light to be collected by telescopic objective after light being dispersed from C.D.S. prism.