Background technology
Laser has the good advantage of monochromaticity with respect to general light source, and promptly line width is very little.Narrow like this spectral line width be after the atom-exciting radiation through the acting in conjunction of number of mechanisms such as resonator cavity with interfere mutually, at last one or more of Xing Chenging stablize, meticulous spectral line, these spectral lines are exactly the mould of laser.Each zlasing mode correspondence a kind of stable electromagnetic field and is distributed, and has certain light frequency.From going to analyze zlasing mode with two angles of direction parallel (vertically) and vertical (laterally) of light output, zlasing mode can be called longitudinal mode and transverse mode.
For laser longitudinal module, Tsing-Hua University's precision measurement technology and instrument National Key Laboratory and Beijing are opened up and are reached JX-1 type helium-neon laser frequency splitting, polarization and the mode competition teaching experiment system that laser apparatus Ltd unites manufacturing and successfully realized the observation of longitudinal mode and polarization state thereof and the demonstration of longitudinal mode splitting and mode competition.But, also there is not the complete experimental system of a cover can realize that colourful laser transverse mode is observed and analysis now for laser transverse mode.
The present invention adopts half exocoel He-Ne laser instrument, the cat ' s eye reflector that utilization is made up of discrete convex lens and concave mirror constitutes loss adjustable laser resonator cavity, change the loss ratio of laserresonator by regulating cat ' s eye reflector, realized changing the effect of laser transverse mode state.Utilize CCD to carry out image acquisition, the storage of computer realization image.
Summary of the invention
The objective of the invention is to set up a cover transverse mode and observe and analyze experimental system, change the laser transverse mode state, realize the observation and the record of transverse mode by observing system by regulating the laser resonance cavity loss.
A kind of laser transverse mode demo system of regulating based on the opal cavity lens loss, form by half exocoel He-Ne laser tube, convex lens and holding adjuster, concave mirror and holding adjuster thereof, ccd image acquisition system, computing machine, be followed successively by computing machine, the ccd image acquisition system, half exocoel He-Ne laser tube, convex lens and holding adjuster thereof, concave mirror and holding adjuster thereof;
Described half exocoel He-Ne laser tube by He-Ne Electric Discharge Laser pipe, kapillary, be positioned at the catoptron of this laser tube one side and the anti-reflection window that links to each other with the pipe neck of described laser tube one side is formed.
The focal length of the convex lens in convex lens and holding adjuster thereof and concave mirror and the holding adjuster thereof equals the radius-of-curvature of concave mirror, and equals the distance between the stream oriented device, forms cat ' s eye reflector;
Cat ' s eye reflector is made up of discrete convex lens and concave mirror.The focal length of convex lens equals the radius-of-curvature of concave mirror, and equals distance between the two.Convex lens are placed in the convex lens groove, and be fixed on the two-dimensional lens support, the two-dimensional lens support realizes that convex lens are perpendicular to the angular adjustment on the optical axial plane, the two-dimensional lens support is fixed on the two-dimentional work bench by a rod sleeve arrangement for adjusting height simultaneously, propping up the rod sleeve arrangement for adjusting height realizes highly regulating, simultaneously by regulate two-dimentional work bench can realize convex lens along moving of optical axis direction and perpendicular to axial direction moving, thereby change between convex lens and the concave mirror spacing and over against the position; Concave mirror is placed in the concave mirror groove, and be fixed on the two-dimensional lens support, the two-dimensional lens support is fixed on the two-dimentional work bench by a rod sleeve arrangement for adjusting height, propping up the rod sleeve regulating device realizes highly regulating, simultaneously by regulate two-dimentional work bench can realize concave mirror along moving of optical axis direction and perpendicular to axial direction moving, thereby change between convex lens and the concave mirror spacing and over against the position.Can also can fix wherein one state simultaneously by regulating the state of concave mirror and convex lens, regulate another person's state, to reach the purpose that changes both relative positions.By regulating the spacing between two discrete components, both pitch attitudes, both are perpendicular to the parameters such as position of beam direction, mainly be back two adjustings in a big way, change the state of opal chamber mirror, regulated the loss of laser instrument inside, also just changed the loss of laser cavity, thereby made a large amount of high order transverse modes by exciting to each rank transverse mode.Whereby, people can observe the transverse mode of each order very easily.This is the device of former any observation transverse mode, and instrument institute is irrealizable.
Described convex lens and holding adjuster thereof, convex lens are placed in the convex lens groove, and be fixed on the two-dimensional lens support, the two-dimensional lens support is fixed on the two-dimentional work bench by a rod sleeve arrangement for adjusting height simultaneously, can realize mobile and perpendicular to axial direction the moving along optical axis direction of convex lens by regulating two-dimentional work bench.
Described concave mirror and holding adjuster thereof, concave mirror is placed in the concave mirror groove, and be fixed on the two-dimensional lens support, the two-dimensional lens support is fixed on the two-dimentional work bench by a rod sleeve arrangement for adjusting height, prop up the rod sleeve regulating device and realize highly regulating, can realize mobile and perpendicular to axial direction the moving along optical axis direction of concave mirror by regulating two-dimentional work bench simultaneously.
Described concave mirror groove and convex lens groove, by center drilling, female, section is the groove and the center drilling of " " shape, has externally threaded annulus to constitute.Between groove and the annulus by being threaded.
Described ccd image acquisition system is characterized in that: ccd video camera is gathered laser beam transverse mode style, by video line input computing machine, gathers imaging by the image pick-up card in the computing machine, shows on computers and stores.
The system unit annexation: system is followed successively by computing machine from left to right, ccd video camera, half exocoel He-Ne laser tube, convex lens and holding adjuster thereof, concave mirror and holding adjuster thereof.Initial position is: ccd video camera optical center axle, the optical axis coincidence of half exocoel He-Ne laser tube central shaft and convex lens and concave mirror.Convex lens and concave mirror spacing should satisfy the condition that constitutes cat ' s eye reflector: distance between the two equals the focal length of convex lens, and equals the radius-of-curvature of concave mirror.
System's control method: the main regulating element of native system is for constituting the discrete component of cat ' s eye reflector: convex lens, concave mirror.The two all can carry out the plane pitch regulation, along the mobile adjusting of optical axis direction with perpendicular to the mobile adjusting of optical axis direction.Can also can fix wherein one state simultaneously by regulating the state of concave mirror and convex lens, regulate another person's state, to reach the purpose that changes both relative positions.By regulating the spacing between two discrete components, both pitch attitudes, both are perpendicular to the parameters such as position of beam direction, mainly be back two adjustings in a big way, change the state of opal chamber mirror, regulated the loss of laser cavity, thereby made a large amount of high order transverse modes by exciting to each rank transverse mode.
The present invention adjusts the laser resonant cavity loss ratio by the cat ' s eye reflector of being made up of discrete component, thereby can control the output state of laser transverse mode.The present invention can utilize same laser tube to observe colourful laser transverse mode state, and can help the analysis of zlasing mode and the understanding of Principles of Laser by the change procedure of computer recording transverse mode in regulating the cat ' s eye reflector process.These all be before this instrument (system) can not finish.
Embodiment
The present invention is a new pattern laser transverse mode scope, Fig. 1 is the laser transverse mode demo system structural representation of regulating based on the opal cavity lens loss, half exocoel He-Ne laser tube is by 2 anti-reflection windows, 3 kapillaries, 4 laser tubes and 5 concave mirrors are formed, and the resonator cavity of half exocoel He-Ne laser instrument is made up of the cat ' s eye reflector that 5 concave mirrors and 1-1 and 1-2 form.Cat ' s eye reflector is made up of 1-1 concave mirror and 1-2 convex lens, and the 1-1 concave mirror is placed in the clamping device, and clamping device is made up of 18 concave mirror grooves and 19 concave mirror end caps.18, on the 19 concave mirror clamping device stuck-at-7 two-dimensional lens supports of forming, the two-dimensional lens support is by on 16 spiral poles and 15 screw sheel stuck-at-s, 4 two-dimentional work bench.15, the 16 spiral branches rod sleeve arrangement for adjusting height of forming can realize that the height of concave mirror regulates, thereby two-dimensional lens support 17 can be realized the angular adjustment of concave mirror and regulates the bright dipping of laser instrument and the one-piece construction in opal chamber.The clamping device of 1-2 convex lens is made up of 9 convex lens grooves and 8 convex lens end caps, on the clamping device stuck-at-0 two-dimensional lens support, 10 highly adjustings of spiral branches rod sleeve arrangement for adjusting height realization by 11 screw rods and 12 screw sheels composition, and the spiral branches rod sleeve is fixed on the two-dimensional adjustment frame 13.Axial adjustment and vertical axial direction by two- dimentional work bench 13,14 are regulated, and the two dimension angular of two- dimensional lens support 10,17 is regulated, mainly being back two regulates in a big way, the location status of concave mirror or convex lens changes, thereby change the one-piece construction of cat ' s eye reflector, and then the loss ratio of change laserresonator, realized the adjusting of laser transverse mode.The light beam of laser output enters in the 6CCD camera, and CCD camera 6 links to each other with computing machine 7, and computing machine 7 is realized the observation and the record of laser transverse mode.
Fig. 2 is the cat ' s eye reflector structural representation of being made up of convex lens and concavees lens.1-1 is a concave mirror, plates the film that is all-trans in concave surface one side, and 1-2 is convex lens, two-sided plating anti-reflection film.The change of the mutual alignment relation of concave mirror 1-1 and convex lens 1-2 can change the loss ratio of laserresonator, realizes that transverse mode is regulated and control.