DE2500798A1 - OPTICAL MEASURING SYSTEM - Google Patents

Description

ERNST LEITZ GMBH

UnMfZeIdMn ₁ A 1 9 ·> 7 / υ 285't 633 Wetzlar, den. Dec 18, 1974

Pat Lü / Pe

Optical Mef-Ssysterii

The invention relates to an optical heating system for measuring of lengths, inclinations or optical constants the moire fringe or interference fringe principle.

Such measuring systems are known per se in various forms. For example, in the German patent specification 1 136 83 ^ an optical scanning system for measuring changes in position according to the two-phase principle by detecting the mutual displacement of two optical grids to one another is described, in which an optical imaging system is provided between the two grids, which are mapped onto one another which generates at least two mutually offset partial images, each of which is assigned a photoelectric receiver, whose output signals are shifted in their phase position by an angle / η 180 (where η is an integer) and therefore in addition to the measurement result obtained by counting provides information about the direction of movement between the grids. A practical application of this measuring principle is described in German patent specification 1 099 182, which has a reading device for measuring graduations as its content. Furthermore, a measuring and recording device is known from the German patent specification k99 5k5 , in which an interference fringe system is assigned three nested photoelectric receiver groups, spatially offset by defined amounts, whose output signals are each fed to a winding of a rotary field generator.

ßAD ORIGINAL -

609829/0310

A Τ ;;> 7 / Β 2854

_Ä 18. 12.

Patent Department Ä

The anchor of this encoder is then positioned according to the signals oin present (Fig. 2). Also known from DAS 1 G'JS 28 ') nine is a device for determining and controlling the change in position of an object in relation to a dev.ugssysteiu, in which a measuring field is opposed to a line of Potoelclctrischen Eüipfänder, whose separating edges in relation to the "measuring direction sctiräj; ve rl au Ten.

The invention was based on the object of an optical To develop MeUsystem in which the in series arranged Receiver dos i'otoelektrisc'ipn receiver system are arranged differently so that for the receiver system Space can be saved, which is advantageous in the targeted miniaturization of such devices brings.

In the case of measuring systems, this task is mentioned in the introduction Art solved by the fact that a centrally symmetric resp. centrally oriented photoelectrically oriented receiving surfaces ^ s Pünp catcher system is provided and arranged in this way is that straight lines which go through the centers of gravity of these surfaces and preferably parallel to both Image plane as well as to the moiré or interference fringes run, have the same distances from one another in pairs. The receiving surfaces can with the surfaces dor photoelectrisciien receiver of the system coincide. It but can also between the receiving surfaces and the their associated photoelectric receiver optical and / or light-conducting components can be inserted.

The advantage of the measuring system according to the invention is that that with him for the photoelectric receiver system only little space is required.

6 09829/0 8VO _M

α ι >> yy / B 2L '> jh

, Λ Ui. 12. WTk

Patent department sj ■

DIo Ki-rintluri /, lsi below based on in dor drawing Schematic dai'go s te J. lieu exemplary embodiments are described. Show it

Fig. 1, 1a a linear step generator with the invention Arrangement of photoelectric Reception fl. Ictien;

Fig. 2 shows a ^hint: how the invention is based on the arrangement of the photoelectric reception area;

Example of a device / ur determination optical Constants;

a - 4i exemplary embodiments for the photoelectric Receiver system including its orientation.

In Fig. 1 is a measuring system for measuring lengths or movements according to a coordinate direction; shown at which two linear raster 10 and 11 cooperate. That Grid 10 is illuminated by a light source 12 via a condenser 13 and is connected to the not shown, object to be measured connected. Its marks are oriented perpendicular to the direction of movement. The grid 11 is at the front end of a fixedly mounted fork-shaped Holder 14 attached in such a way that its brands are oriented slightly obliquely to the direction of movement of the grid 10. Through the interaction of the two grids horizontally directed moire stripes result, which in the case of a relative movement of the grid in the direction of measurement transversely to this direction over the grid 11, like this is shown enlarged in Fig. 1a. A lens 15 depicts the moiré fringes in a plane 16 in which four centrally symmetrically oriented receiving surface η through four photoelectric receivers 17-20 are defined.

: B 0 9 8? 9 / Π a 1 Π - h -

8AD ORIGINAL

A 1997 / B Z K54

t, December 18, 197 '+

Sponsorship 7 *

Lü / Pe

Win these Επη »five,"; er so an ;; eo, rdnot, that Vr. Rbinduugs lines of their class'ichonschworpuivktp run obliquely to the direction of the Läii ^ sausdohtmii;!; Dor moire stripes. More about the orientation; the Pimpfansflachen is explained in connection with Fig. H. The receivers emit signals that relate to one another in their phase relationship like the functions sin, cos, -sin and -cos. They thus define a four-phase rotation angle.

Fift. 2 shows an angle incremental encoder in which two circular grids 3 ⁽ >, 31, which have different pitches, work together. A lighting device consisting of light source 12 and condenser 13 is used for this purpose, which connects the object measuring with the λλχ measuring object! Tastc-x- '} Λ illuminates the grid 30 corresponding tnipfän ^ are assigned erflachen which also here by four fotoelektrisehe Kmpfän.'jer 17 - 20 were formed directly because of the Uli i, rrs>;.. tiiedlichen pitches of both Ras tor 'JO ₁ 31 yields a pattern of moire fringes, as can be seen from the plan view of the disk 30. upon rotation of the screen 31 results in continuous Koirestreifen and therefrom signals with respect to their phase position behave as described above.

3 shows an example of a measuring system for determining optical constants in the form of an interference refractometer. After passing through a condenser 13, the light from a source 12 enters a prism kO composed of two parts with a partially mirrored separating surface and is split there into two bundles of rays, one of which is a chamber M with a substance with a refractive index n .., the other one such. Kaninu-sr ^ 2 with a substance of the fracture type n "through-

de λ ■

runs. Bex bundles of rays are reflected on a mirror 43, go through the chambers backwards and become

# ■■ -

Potenfabteilune £ 1 ο. 1 2.

tin I'risi'ia 'in wi'Mlfi' uttered. Since in the chamber 41 assigned beam path pin wedge. 44 is inserted, if dip ro f loktiorten Strarilerigänge bei dor Viedervprpiniijun /; They do not close together, but rather they diverge slightly, so that in an IMIHn Done 45 an infectious field results in which the interference fcrei fen are oriented parallel to the outer edge of the prism 4θ and run parallel to the roof surface of this prism. The image plane is assigned four furious flat surfaces, which are also represented here by the surfaces of four photoelectric receivers 17-20 Interfering components and common-mode components cleaned up. The output signals of these amplifiers are used to control a counter. 43 which displays the measurement result.

The figures' la to 4i line execution possibilities for the tangential surfaces and4. their orientation in terms of on the marks or strips to be measured.

In the exemplary embodiment shown in FIG. 4a, four rectangular photoelectric receiving surfaces 4ü-43 are provided, which together define a square. This square lies within the illuminated image field 44 in which interference fringes 45 appear, which can move in the direction of the double arrow 46. If one draws straight lines g parallel to the interference fringes through the focal points S - S of the receiving surfaces. - S ₁ , it can be seen that the arrangement of the receiving surfaces 40-43 relative to the direction of movement de ι * interference fringes indicated by the double arrow is such that these straight lines have the same spacings a from one another in pairs. If you assign a photoelectric receiver to each receiving surface, or if you place the receiving surfaces themselves through the

BAD ORfGiNAL _ ₆

609829 / ÖÖ10

λ 1907 / η 2

uno ^€ · KJ. 12th

LU / Po

cTipri fotocloktrischor Ιΐιιιρ catcher, it turns out that there are (pants Si ^ nalo that relate to the movement of the stripes like the angle functions "sitius", "cos", "minus sinus" and "mimis cos" and. danit a For example, the signal from the reception area k2 corresponds to the "sinus", the signal from hü to the "cosinus", the "signal from" (3 to the "minus Sintis" and finally the signal from kl to the "minus cosine ". These signals are evaluated in a known manner and therefore not explained here any more.

Figures 4b and ^ c show a centrally oriented or a zcntralsymiuc Irish arrangement of the receiving surfaces, the example of Fig. Kh for generating a three-phase rotating field, which are used according to Figure hc x for generating a vior-phase rotating field. Here, too, the straight lines, which are parallel to each other and which are laid through the centers of gravity of the receiving surfaces, are in pairs at the same distance a 'or a ".

. In the example shown in FIG. Kd , the receiving areas hO ¹ - h '} ^{x are} in parallelgram form: i and in such an arrangement in relation to the vu measuring pins h%, that again between those parallel to the strips, through the centroids straight down the same distance a '"result. This arrangement has the advantage over that of Figure ha. shown the advantage of better harmonic filtering.

Instead of the parallelogram curses and circular surfaces can 3An provided as shown in FIG hey.

In all examples shown so far, it was assumed that the area of the photoelectric receiver is the reception area at the same time. But that this too

609829/0810 '' - 7 -

BATH ORIGINAL

Patent department τ 1 :: 1. 1 2. 1 ',' 7 '

Lü / Pe

250G798

may be different, zoic; i <n din after Γ ο Igp-udrm figures in perspective view:

Xn Figure 4f are photoelectric? Receiver 5 ^ inclined, each with a shielding! · cylinder 51 with attached Lens 32 is assigned. As indicated, these are cylinders ! ai fc their lenses relative to the strips to be drawn 45 arranged so that '> the above-mentioned condition of the same spacing in pairs is fulfilled.

This also applies for the example shown in Figure 4g embodiment in which optical fibers in the form of fiber bundles 53, or for the example of Fig. ^'1 Ii, in which μ as a light guide iihonibusprismen ^ are used h. In everyone; In this case, the arrangement of the end faces is already described above.

Finally, FIG. 4h shows that it is also possible to assign a common optical component, here in the form of a pyramid prism 55 with a downstream optics 5, to clon provided snap catchers 5, and thus to facilitate the orientation of the tilt capture surfaces with respect to one another. Here, too, what has been said above applies that, in addition, the centers of gravity of the pyramid surfaces, straight lines laid as receiving surfaces, must be equally spaced from one another in pairs in order to solve the problems mentioned at the beginning.

Variations of what has been described so far are possible. For example, instead of the main part shown in FIG. 4h, a correspondingly oriented pyramid grid can also be provided. This has the advantage that with a suitable choice of the division periods for the pyramid grid and for the hatcher 1 '<) b ^ w. '} Λ can do without the second grid 1 1 or 3 ^f) .

CHiuiHAL

Claims (3)

Potont drainage Li; / P ο '. ' A η s P__ £ __U e he 1.1 Optical measuring system for measuring lengths, angles or ^N - ^y optical constants according to the moire strip or interference strip principle, characterized by the fact that a centrally or centrally oriented photoelectric signal has a star (17 - 20) is provided and arranged in such a way that straight lines (g- - g.) Which go through the centers of gravity (S ₁ S run, have the same distances (a, a ', a ", a"') from one another in pairs. 2. Meßsyston according to claim 1, characterized in that the Kmpfangsflachen (4ü - 43; 40 ^f - 43 ») coincide with the surfaces of the photoelectric receiver of the system. 3. measuring system 'according to claim 1, characterized in that: i between the receiving surfaces (52, 55) and those assigned to them photoelectric receiver (5'-0 optical (5ö) and / or light-conducting components (531 54) inserted are. 2 8/0810 ^ßA ° original Blank page