SU61539A1 - Condenser for transmitted light - Google Patents

Description

Even MV Lomonosov concentrated light energy by reflecting rays in one place with the help of several mirrors. Subsequently, this technique has been applied several times, but usually only under the condition that the reflected rays are directed in the direction opposite to the direction of the rays going from the light source to the reflector, for example, as is the case in various parabolic and other mirror reflectors. We have such an application in projection devices of various types, for example, in film projectors. However, reflectors of this type are inconvenient, since:

1) the light source illuminates part of the reflector floor and 2) overall dimensions are too large.

The subject of the invention is a reflective condenser, which is completely free from these disadvantages and makes it possible to cover a large solid angle of radiation of the source in transmitted light.

Imagine a series of narrow cylindrical rings / (fig. 1) of thin tin arranged concentrically around a common axis. The inner cylindrical surface must be a mirror. The radii of rings 1 increase in proportion to the increase in the tangent of the aperture angle.

The rays lying on the main optical axis from the light point 2, which form the diverging beam, fall on the inner mirror surfaces of the rings / and are reflected towards the main experimental axis, collecting in a relatively small volume.

The path of the rays is depicted in FIG. 1, where a section of a row of rings is represented by a plane passing through an axis.

FIG. Figure 1 shows that all practical rays in a solid angle, the top of which is in the luminous point, and the base of which is the largest ring, converge in volume on the optical axis; the diameter of the volume is equal to the double width of the aperture angle zone between two adjacent rings.

Obviously, what the rings 1 will be, i.e., the smaller their sizes along the generatrix of a cylindrical surface, the narrower the zones between them should be, the more perfect the collective action of the whole device.

The collective action, depending on the value of the minimum cross section through which the luminous flux behind the condenser must pass, can be further increased if the reflecting rings are made not cylindrical, but are areas of surfaces suitably selected (Fig. 2). Then the area of the minimum cross section of the outgoing beam of rays will be equal to the area of the source plus the aberrations, otherwise, we get a device that is completely analogous to a conventional condenser.

Since on: the value of the device is reduced only to the concentration of the luminous flux and it should not give an image, and consequently, the question of resolving power disappears, the requirements for the optical correctness of the reflecting surfaces are minimized. Even a wavy surface of the curved ring can still provide a sufficient concentration of light, as long as it has a high reflectance (85-90 / o).

Even with a low coefficient of reflection of the surface of the rings, the loss of light on reflection in the described instrument will be less than in a conventional glass two-lens condenser with four reflecting surfaces.

For ease of manufacture, it is possible to somewhat change the design of the device, simplifying it by some deterioration in optical properties, namely: to replace individual rings with a flat spiral (like a clock spring, rolled up from a shiny thin mirror tape) - with metal, plastic, glass or other material ( Fig. 3). It is only necessary that the pitch of this spiral increases in proportion to the tangent of the aperture angle of the light source. This will increase somewhat the aberration, but with a light source with a luminous body of considerable size does not entail a strong decrease in illumination in the plane of the minimum cross section of the outgoing beam of rays.

The described condenser is achromatic and is distinguished by the fact that the apertures of the incoming and outgoing beams of rays are always equal to each other. Moving the source away causes the same moving away to the minimum cross-section planes (maximum illumination), with dark zones appearing from the light rays passing through the condenser without reflection or reflected to the sides.

Thus, the described condenser may be referred to as a constant-aperture condenser.

It is possible to build the device on the same principle with a different aperture ratio than the one. To do this, we should take rings not cylindrical, but tapered and arrange them not in the same plane, but shift them somewhat along the optical axis so as to intercept the entire aperture angle and direct the rays of all zones to one section of the axis (Fig. 4). This will complicate the manufacture, but, taking into account the reduced requirements, is still not enough to devalue other advantageous features of the device.

The device was built by the author for the purpose of the concentration of ultraviolet rays from the arc lamp PR.I lecopy experiments and luminescence analysis. The prototype fully justified all the calculations.

You have dreamed that a condenser of this type can have a very diverse use, far beyond its original purpose.

The condenser is suitable for portable projection apparatus and episcopes of those types in which the volume and weight of the apparatus must be reduced. In the form of a spiral ribbon, it is particularly suitable for children's projection devices, since the cost of making it is negligible and for this purpose all thinning tin is suitable.

On condition of a more thorough production, the new condenser is suitable as an illuminator for microscopes, micrographs, and microprojection apparatuses, especially when working with ultraviolet light.