Which lens is used in flashlight?

The benefit of instant control, and the absence of flame, meant that hand-held electric lights started to replace combustion-based lamps like the hurricane lantern. Flashlights became extremely popular in China; by the finish of the 1930s, 60 companies made flashlights, some selling for less than one-third the price of equivalent imported models. Miniature lamps developed for flashlight and automotive uses became an important sector of the incandescent lamp manufacturing business. ANSI standard FL1 does not specify measurements of the beam width angle but the candela intensity and total lumen ratings can be used by the consumer to assess the beam characteristics. If two lights have similar candela ratings, the light with higher lumen value will produce a wider beam and can light a wider area overall. Typically a good flashlight beam with a small hot spot could have some light visible as “spill” around the spot.

You will also find lenses in binoculars and telescopes, though not absolutely all microscopes use them. Ordinary microscopes use a series of glass lenses to magnify tiny objects, while super-powerful electron microscopesuse electromagnets to bend electron beams that help us see in even more detail.