1- Plain mirror:
Used when a fixed light source is used.
2- Concave mirror:
When skylight is used, this mirror helps to converge the beam onto the condenser.
3- Sub-stage lamp interchangeable with mirror:
Where there is no electricity or battery, mirror can be used.
4- Built-in sub-stage lamp (Tungsten filament or halogen lamp) with intensity adjustment:
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Source: Practical Pharmacognosy - Dr. K. R. Khandelwal
