Sentence Examples

  • In the last the field is full of false light, and it is not possible to give sufficiently minute and steady separation to the images; and there are of necessity a collimator, two prisms of total reflection, and a small telescope through which the rays must pass; consequently there is great loss of light.
  • Spectroscopes generally consist of three parts: (I) the collimator; (2) the analysing appliance, (3) the telescope.
  • The slit of the collimator confines the light to a nearly linear source, the beam diverging from each point of the source being subsequently made parallel by means of a lens.
  • The lens may then be also dispensed with, and the whole collimator becomes unnecessary if the luminous source is narrow and at a great distance, as for instance in the case of the crescent of the sun near the second and third contact of a total solar eclipse.
  • The general results may be summarized as follows: if the width of the slit is equal to fX/4D (where X is the wave-length concerned, D the diameter of the collimator lens, and f its focal length) practically full resolving power is obtained and a further narrowing of the slit would lead to loss of light without corresponding gain.