US_Patent_755840-Jagadish_Chandra_Bose-Detector_for_electrical_disturbances_fig_1-3.png
Summary
Description US Patent 755840-Jagadish Chandra Bose-Detector for electrical disturbances fig 1-3.png |
English:
A galena semiconductor
crystal detector
for
microwaves
invented by Indian physicist
Jagadish Chandra Bose
during his landmark
millimeter wave
optics experiments 1894-1900. It consists of a tiny crystal of the semiconducting mineral
galena
(lead sulfide, PbS)
(4)
with a metal point
(5)
making electrical contact with it, at the focus of a lens
(13)
which focuses microwaves on it. A battery
(18)
passes direct current through the contact and a
galvanometer
(19)
measures the current. When microwaves strike the crystal they reduce the resistivity of the contact, and the galvanometer registers an increase in current. The pressure of the point can be adjusted with a thumbscrew
(7)
. Bose used it to detect microwaves in the frequency range from 12 to 60 GHz generated by a spark transmitter in the first historic experiments with
millimeter waves
, in which he duplicated classical optics experiments, demonstrating refraction, diffraction, polarization, and standing waves, proving that microwaves are
electromagnetic waves
predicted by
James Clerk Maxwell
in 1873. The detector is deliberately built to resemble and function similarly to a human eye; due to Maxwell's theory, physicists of this era regarded radio waves as "invisible light". Bose called his detector an
artificial retina
. This was the first
crystal detector
(
semiconductor diode
) and is often considered the first patent on a semiconductor device.
Alterations to image: cropped out surrounding heading text and signatures. |
Date | |
Source | Retrieved from US Patent 755840A Jagadis Chunder Bose, Detector for electrical disturbances , filed: 30 September 1901, granted: 29 March 1904, fig. 1-3 on Google Patent search |
Author | Jagadish Chandra Bose |
Other versions | US Patent 755840 (Bose's Microwave Apparatus).djvu is a version with surrounding text and signatures included |
Licensing
Public domain Public domain false false |
|
In general
,
the contents of United States patents are in the public domain
.
In specific cases , patent applicants and holders may claim copyright in portions of those documents. In those specific cases, applicants are required to identify the portions that are protected under copyright, and are additionally required to state the following within the body of the application and patent (see 37 CFR 1.71(d) & (e) and 37 CFR 1.84(s) , and MPEP § 608.01(e) & (w) and MPEP § 1512 ):
The original patent should be checked for the presence of such language before an assumption is made that the contents are in the public domain. (This template can be replaced by {{PD-US-patent-no notice}} in such cases.) |
Public domain Public domain false false |
This media file is in the
public domain
in the
United States
. This applies to U.S. works where the copyright has expired, often because its first
publication
occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See
this page
for further explanation.
|
||
This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the
rule of the shorter term
for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See
Wikipedia:Public domain
and
Wikipedia:Copyrights
for more details.
|