Microscope Object Lenses Tube

Exercise No-1

Acquaintance with a microscope and other laboratory (equipments.)


To get mastery of the use of the microscope which is the basis to go through understanding of I microbiology


The lenses in this instrument all so adjusted that minute object invisible to naked eyes are magnified and made visible. There are two types of microscopes is common I use,
       1)   Simple microscope - Only one lens Cor one set
      of lenses) is used in between the eye and teat- Hand lenses f dissecting microscope
       2)   Compound Microscope - Two or more than
two lenses Cor set of lenses) are used in between the eye object and this helps     in obtaining more magnification . eg. Student's microscope, Research microscope.

Parts of Student's Microscope


       1)   Eye piece (ocular)
      A single set of lenses placed on the - Upper End of a body tube with uusual magnify
cation of 5x , 10x , 152, etc. The function of eyepiece I is to O magnify the object to a    certaind extent.
2)   Body tube Coraw tube) »
      Tube holding the eyepiece and the objective | lenses at upper and lower end respectively.
It is filted to the arm by back and pinion I arrangement for upward and downward   movement.
the length of the tube is fixed f is generally F160mm.
3)   Obiective lenses
One or more Sets of lenses are fitted to the lowes end of body tube.with the help of devolving noseniece

Thebe ape telo objectives in student's microscope :-

1)   Lopower objective = it is having ragnification of 10x 'or 20x
2)   High power objectives - It is having magnification 44x or 62
4)   It is a curved, solid, steel frame holding the draco tube at upper and stage at lower end.
      It is fitted to the pillar by  an inclination joint.
5)   Stage and clips :-
Stage is useful for placing the object slide, where as clips are used for holding the object   slide.
6)   Inelination joint –
Pt is used for changing inclination of the microscope to a certain extent for easy observation.
7)   Course or rough adjustment Screw :-
It is meant for bringing the microscopic objects after focusing! by course adjustment of the microscopic object under focus.
8)   fine adjustment Screw -
It is fove sharp focusing of the microscopic
obiect after focusing by course adjustment Screw
9)   Pillar & borse shoe shaped base :
It is the basal part bolding the arm & other parts in balance.
10)  Mirror
A mirror with two surfaces (concave & plain)  is fitted to the pillar for reflecting light  to the object
11)       Diaphragm —
     It' is a metal disc with adjustable Centocel holes For controlling the quantity of light.

Microscope Object
Microscope Object  

Iinstruction for use of microscope –

1)   It is a coastly and delicate instrument. Handle it with maximum care.
2)   clean all Optical parts, mirror and condenser I before use. use seperate cloth to clean body of microscope.
3)   Use the microscope in Vertical position, keep it to face the light source but avoid direct' Sunray's.
4)   focus light under, low power objective with mirror,
5)   Do not mount bot or flooded slide under the microscope
6)   Select Suitable microscopic Jield under low Land there observe it under high power or immersion objectives
7)   Never lower down the objective while viewing through eyepiece protect & slide from breakage, first lower down the objective just to touch the condo slip & lift it | upwards to focus while viewing through eyepiece.
8)   clean the oil' immersion objectives ofter use with xylol & wipe out with muslin cloth.
9)   Turm to low power objectives while replacing the
      Slide or closing the work.

Methods of sterilization and disinfection -

Object - To keep the material Free from micro-organisms
Sterilization - it is a process by means of which material is made sterile or free from living micro - organisms either by killing or by seperating them.
It is essential to sterilize cultural media glass ware and other laboratory instrument before their
use to avoid contamination. In pure culture Studies, different physical & chemical means are used foll this purpose which will are follow"
Microscope Object Lenses Tube
Object Lenses 

1) physical agents -

  i) Heats -
 a) Dray : 1) Direct ; Eg. flame 2) Indirect ' l.e Hot air over
 b) Moist :1) Steam without  pressure - Arnold steam sterilizer. 2) Steam with           pressure - autoclave.
 ii) Filters – 
a)   for liquids – porcelain on glass filters like- (a) chamber land (b) Berkefeld  (c) seitr
b)   for gases – cotton fibers etc.
 iii) light. - Ultraviolet rays : (2) Germicidal lamps.

2) chemical agents –

1)     Inorganic KM No 4, Iodine
2)      Organic – phenol, formaldehyde, ethyl alcohol etc.

Principle —

The material is exposed to ordinary steams i.e. 100-110 °C for 20-30' minutes and the process is repeated for successive 2 more days with an inteoval of 24 hrs. This repeated treatments kills the Resistant Spare farmers that germinate during the info retted' period , The process is also known as fractional or process is also known as fractional or intermitted' Sterilization or Tantalization.
The apparatus . Arnold Steam Sterilizer' consist of double walled copper chamber with a water holding trays at the bottom. The material to be sterilized' is placed on perforated sieves Steam rising from bottom . beats. The material, gets Condensed at the top and returns to be boiling trays through the space in between two walls. Heating
can be done' by either electric beaters or gas burner.
Moist heating the steam under pressure (Autoclave)-
Culture media like potato Dextrose Adale (P.D.A), nutrient broth (NB), Nutrient agar (N. A). and soil, water, sand manure etc, which are not damaged by high temperature of the steam under
pressure has high temperature and more power that is penetrating and bence. It is the quickest method Materials usually sterilized by direct beating or bot air can also be sterilized by this method. The apparatus used in this method is called as autoclave.

Precautions to be taken while working with autoclave

1)    Equipment must be in cooking Order,
2)   Siefficient water should be filled before beating a
3)    pressure is allowed to rise only when all air from in side is semoved through air cock
4)   alben desired pressure is obtained . It is maintained for specific time.
5)   After sterilization, the appratus is allowed to cool docoon and the pressure is slowly seleased before opening

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