There is an ongoing discussion whether patents encourage or hinder innovation. Patents grant a temporary monopoly as an incentive for the inventor to commercialize the inventions and come up with follow-up innovations. However, many companies file patent applications to block competition even though the companies owning the patent do not intend to commercialize the invention.
It is tempting to speculate what would have happened to many technologies were they patented or not. Although we can’t go back in time, we can see how patents or lack thereof have influenced the spread of technology and its subsequent innovations. One such example is the invention of the telescope.
The earliest telescopes were built at the beginning of the 17th century in the Seven United Provinces (present day Netherlands). Three individuals, Hans Lippershey and Sacharias Janssen (spectacle-makers in Middelburg), and Jacob Adriaenszoon Metius of Alkmaar are widely credited with building the first working telescopes, although the matter is apparently far from being resolved .
Their telescopes were made of two lenses to form an image: a convex objective lens and a concave lens in the eyepiece (therefore these telescopes did not invert the image) and had a modest magnification of around 3x. In October 1608 Hans Lippershey applied for a patent for an instrument “for seeing things far away as if they were nearby,” but the patent was denied due to claims of the other inventors. Jacob Metius applied for a similar patent but the request was also denied on similar grounds.
Italian Giambattista della Porta claimed also to be the inventor of the telescope, but died while preparing a treatise (De telescopiis) in support of his claim. In his book Magiae Naturalis (part XVII, chapter 10, 1558) he wrote however:
With a Concave lens you shall see small things afar off very clearly. With a Convex lens, things nearer to be greater, but more obscurely. If you know how to fit them both together, you shall see both things afar off, and things near hand, both greater and clearly.
Many other inventors such as the Catalan Juan Roget, or the Englishmen Leonard Digges and Thomas Harriot  have also claimed inventing the telescopes but the evidence in their support is very weak.
In May 1609, during a stay in Venice, Galileo Galilei (1564-1642) received a letter from a former pupil. In it the “spy-glass” or the “Dutch perspective glass” of Lipperhey was described. Back in Padua, where he held a professorship, Galileo immediately (reportedly within a month) built such instrument with a set of convex and concave lenses along the way perfecting several elements and making the instrument much more powerful. He ingeniously used it to look at the sky and made many fascinating observations, which he described in Sidereus Nuncius (1610). Galileo’s discoveries were widely admired. In 1610 Galileo was first to observe the four major moons of Jupiter. (The names however were given by his rival Simon Marius (in Mundus Iovialis, 1614): “Io, Europa, the boy Ganymede, and Callisto greatly pleased lustful Jupiter.“)
Galileo observed also spots on the sun, the phases of Venus, and the hills and valleys on the Moon. His fame grew up so much that the instrument was known by the name of Galilean telescope.
Initially the telescope was identified by a variety of names, among them the optic glass, perspective glass, truncke-spectacle, trunk glass, perspicillum, conspicillum, mathematician’s perspicil, occhiale, specillum, and penicillium. The modern name “telescope” (τηλεσκόπος, teleskopos “far-seeing” from the Greek τῆλε, tele “far” and skopos “seeing,” itself from σκοπεῖν, skopein “to watch.“) was invented on April 14, 1611 at a banquet held by Prince Federico Cesi in honor of Galileo Galilei at the Accademia dei Lincei (Academy of the Lynxes) by the Greek poet, theologian and mathematician Giovanni Demisiani (or Demiscianus) of Cephalonia . (In the Sidereus Nuncius, Galileo had used the term “perspicillum” or “organum” and “instrumentum.“) Grant McColley  argues that the widespread adoption of this name was partially due to a treatise on astronomy by Josephus Blancanus “Sphaera Mundi” (1620). In his book, Blancanus consistently and repeatedly used the word “telescope” and the book was widely popular and reprinted at least four times during the 17th century.
The earliest depiction of a telescope was engraved by Adriaen van de Venne and included in the “Emblemata of zinne-werck” (Middelburg, 1624) by the poet Johan de Brune (1588-1658).
Lack of patents for the invention may have been the reason for the great popularity of the telescope during the next centuries and the many discoveries and innovations in optics, astronomy, and biology.
The telescope was not patented until 1851 when Alvan Clark received a patent for his version of the telescope. At that time, however, optics and optical instruments have already improved a great deal.
 Huib J. Zuidervaart, The ‘true inventor’ of the telescope. A survey of 400 years of debate.
 Grant McColley, Josephus Blancanus and the Adoption of Our Word “Telescope”, Isis, 28, 2, 364 (1938).
 Edward Rosen, The naming of the telescope, Henry Schuman, New York, (1947).