GB2116724A - Microscope for measuring and displaying dimensions electrically - Google Patents

Abstract

A measuring mark 1 on a carrier 2 in a microscope eyepiece is moved during calibration and measurement and a transducer 51 produces signals representative of carrier position. The signals are converted at 71 and processed by circuits 91 and 13 into which a range is set at 16 according to the magnification used and the resulting measurement is displayed at 17. The measurements can be made along one direction or two orthogonal directions and the apparatus can be adapted for use with a zoom objective lens. <IMAGE>

Description

SPECIFICATION Microscope apparatus for measuring and displaying dimensions This invention relates to a measuring instrument for a microscope of the type having an eyepiece provided with a mark on a measuring mark carrier which is displaceable in the optical path and apparatus for digitally displaying the dimensions of an object being observed.

Known instruments of this general type have a length measurement transducer with an adjustable cross wire visible in the optical path, the apparatus being arranged so that the signals produced by the transducers are proportional to the cross wire displacement. In addition, in the plane of the cross wire, a reticle or graticule can be provided within the microscope.

In such an instrument, for each magnification setting, a standard gauge or master gauge is inserted for calibration in place of the object which is being observed. Calibration is accomplished by associating a known line on the standard with a line on the graticule corresponding thereto. After each magnifiction change, recalibration is necessary.

Each calibration process takes a long time and is therefore expensive. In addition, there is a substantial risk of incorrect setting.

According to the present invention there is provided an apparatus for producing and digitally displaying a length measurement of an object positioned in the optical path of a microscope of the type including an eyepiece having a measurement mark carrier with a measurement mark thereon, the carrier being movable transversely with respect to the optical path, the apparatus including:: transducer means to be coupled to the carrier for producing output signals representative of positions of said carrier; memory means for selectively storing said output signals; means coupled to said transducer means and said memory means for producing a measurement signal representative of the distance between two positions of said measurement mark; range switch means for establishing a predetermined range of length measurements; means responsive to said range switch means and said measurement signals for producing a scaled signal indicative of a dimension represented by the two positions; and means for displaying said scaled signal.

The invention also provides a microscope provided with such apparatus.

Thus the invention can provide a simplified and partially automated method and apparatus for calibrating a measuring instrument of a type capable of measuring at least one dimension, and in preferred forms the apparatus can be effective along two coordinates, the diagonal associated with the two coordinates being continuously determinable by means of calculating devices.

In order that the invention may be more clearly understood, the following description is given by way of example only with reference to the accompanying drawings, in which: Figure 1 is a simplified schematic diagram of a portion of the optical system of a microscope in conjunction with a first embodiment of an apparatus for measuring and displaying dimensions of an observed object; Figure 2 is a view similar to Figure 1 showing a second embodiment of a viewing and measuring apparatus in accordance with the invention; Figure 3 is a similar schematic diagram showing a third embodiment of an apparatus in accordance with the invention; and Figure 4 is a similar schematic diagram showing a fourth embodiment of an apparatus in accordance with the invention.

Referring now to the drawings in detail, the left-hand portion of Figure 1 schematically illustrates a portion of the optical system of a microscope of the type having a viewing objective lens 41 and an eyepiece assembly 3 for viewing, as well as for measuring the dimensions of, the objects under examination. The observer's eye is positioned above the eyepiece. The objective lens 41 is adjustable, in a conventional fashion, to make it possible to set different magnifications of object 42. This can be accomplished in any of several known manners including by mens of various interchangeable lenses, by a lens turret or by the use of a zoom lens.

Eyepiece assembly 3 contains an adjustable measuring mark carrier 2 which has on it a measuring mark 1 which can be employed for the length measurement of object 42 and for the prior calibration at the desired magnification or measuring range. The instrumentation for measuring and displaying the length, which must be recalibrated for each magnification range, is shown to the right of microscope 4 in Figure 1 as an electronic circuit.

Prior to the actual length measurement, calibration takes place at the desired magnification range.

This calibration process takes place as follows: A calibration standard which can be in the form of a plate or bar having marked thereon a series of visible calibration lines for different length measurements is placed on the objective stage of microscope 4 in place of object 42. The standard can have various calibration lines for various length ranges such as, for example, 0-0.75 mm, 0-1.5 mm, or 0-28 mm. The actual calibation process is performed by looking through the viewing lens assembly and adjusting the measuring mark carrier 2 until the mark 1 thereon reaches the zero mark inscribed on the standard. The mark on the carrier can be a line or a cross, the carrier itself being transparent.The carrier is displaced laterally relative to the optical path by rotation of the knarled knob 511 which is mounted on a threaded shaft, permitting the carrier to be moved to the left and right, as illustrated in Figure 1. A measurement transducer 51 is coupled to the mechanical shaft which moves the carrier and produces electrical signals representing each of the positions of measuring mark carrier 2. These signals are conducted to the electronic circuit which includes a measured value converter 71 which converts thje signals and delivers them to a computing element 91.

The conversion can be analog-to-digital or can be analog conversion or digital format conversion, depending upon the choice of devices for transducer 51 and the subsequent computing devices.

When mark 1 is aligned with the zero position of the calibration standard, the carrier is regarded as being in its zero position and the operator momentarily closes resetting switch 81 so that the signal produced by transducer 51 and converter 71 can be conveyed to a store or memory 101. Computing element 91, which continuously receives the position signals from data transmitter 51, is thus informed by store 101 that the signal being received in this circumstance is the zero point signal of the select magnification range. Element 91 continuously or repetitively computes the difference between the signals supplied to it by store 101 and converter 71.

Thus, the value produced is referenced to the zero position stored in store 101. In a fully digital embodiment, element 91 can be simply a counter, adding counts to the value in 101. By means of knob 511, the operator then moves the measuring mark carrier 2 until mark 1 reaches the end of the calibration line, e.g., 1.5 mm. The operator feeds the selected measuring range N as a code into range switch 76 which can be, for example, in the form of one or more thumbwheel switches. The operator also momentarily closes calibration switch key 11 so thatthe position ofthe measuring mark 1, at 1.5 mm, passes into a second computing element 12 as the calibration line end.Because the measuring range N fed into the range switch 16 is already in the third store 15, the second computing element 12 can calculate a scale factor M and store it in a second computing element 14which also receives the range signal for measuring range N which was predetermined by switch 16. These values are then available to a third computing element 13 for the actual measurement process.

Computing element 12 divides the output from 91 by the range factor N which is stored in memory 15 when switch 11 is closed to arrive at the scale factor M which is then stored in memory 14. Element 13 is a multiplication device which multiplies the output of 91 with the scale factor from memory 14, that value having been scaled as described. The various computing elements are thus commonly available elements.

It will now be assumed that an object such as a small screw or an electronic printed circuit is to be placed in the position of object 42 and features thereof are to be measured. The operator rotates knurled knob 511 until mark 1 of carrier 2 is aligned with a selected portion of the object. Resetting switch 81 is again momentarily closed, thereby establishing the zero position of that feature on object 42 in the first computing element. The operator then rotates knob 511 to move mark 1 across the screw or electronic circuit portion to be measured to, for example, the other end of the portion.The position signals generated by transducer 51 are delivered through converter 71 and computing element 91 to computing element 13 where they are processed, taking account of the values from the calibration process, and the results of this arithmetic are delivered to display 17 or, when switch 181 is closed, to printer 18.

The measuring process accomplished by the apparatus of Figure 1 has only been described in connection with one coordinate direction. It is, however, possible to measure in several coordinate directions as will be shown hereinafter in connection with the embodiment of Figure 4. In the measuring process of Figure 1, the so-called zero point can be placed at any random point of object 42.

If, for some reason, the magnification range must be changed, a calibration process is required for the new magnification range. Such a calibration process can easily and effortlessly be performed with the embodiment of Figure 1 because it merely requires the operation of reset switch 81 to establish the zero point of the calibration standard, the operation of key 11 for fixing the actual scale and the operation of range switch 16 if the range is to be changed. The calibration values are thus stored for each magnification range. This also applies for different calibration lines within the same magnification range. With this apparatus, it is a simple matter to store calibration or reference values even in the event of a power failure by simply supplying a battery to operate the overall system, the battery being substituted for a conventional power supply, not shown.

Figure 2 shows an embodiment employing the components of Figure 1 and with the addition of a drive for the viewing objective lens 41. In the embodiment of Figure 2, the lens is constructed either as a lens turret or a zoom lens and the magnification ranges are selected by a magnification range change drive device 6. A range switch 61, which can be constructed as part of drive 6, provides electrical signals representing the set magnification range to the store 14 and store 15 through signal converter 19. In the embodiment of Figure 2, the calibration and measuring processes take place in the same way as described in conjunction with Figure 1 except for the power drive of the objective 41.

Athird embodiment of an apparatus in accordance with the invention is shown in Figure 3 in which a zoom lens is used as the observing objective lens 41.

With the aid ofthe magnification range change drive, the magnification range of the zoom lens is adjusted over the entire range in a continuum rather than in steps. The electrical signals representing the values of the magnification ranges are supplied by range switch 61,through signal converter 19, to an interpolator 20 as well as to memories 14 and 15.

Interpolator 20 interpolates the scale factcrs M located between the individual fixed points of the magnification ranges. Here again, there is no need to set the magnification values associated with each magnification. As a result, a continuous, automatic measurement is possible because the calibration for individual magnification values takes place as fixed points. Thus, the calibration and measuring sequence is the same as in the preceding embodiments.

Whereas the previously described three embodiments permit calibration and measurement in only one coordinate direction, e.g., either in the X direc tion or in the Y direction, the fourth embodiment which is shown in Figure 4 permits calculation in both coordinate directions. Thus, circuit components 51,71,81,91 and 101 are used for the X coordinate measurement and parallel circuit components 52, 72, 82, 92 and 102 are used for the Y coordinate determinations. The latter circuit elements are of the same nature as those previously described in connection with Figures 1-3. The outputs of the two parallel circuits formed from these components are delivered to a computing element 21. In principle, the calibration process and the measuring process are the same as in the three other embodiments.The operator sets the measuring mark 1 of carrier 2 by operating the knurled knobs 511 and 521 to move the carrier in the X and Y directions, respectively, by threaded orthogonal mechanical drives. Movements in the X direction cause values produced by transducer 71 to be sent to computing element 91. In the Y coordinate direction, the values produced by transducer 52 are delivered through converter 72 to the second computing element 92. When the measuring mark 91 is set on a zero point during the calibration or measuring process, the switches 81, 82 are momentarily operated for both coordinates so that the so-called zero values can be delivered to memories 101 and 102.If mark 1 of carrier 2 is then moved along the calibration standard, or the actual object being measured, by moving knobs 511 and 521 the individual movements in the coordinate directions are processed in the additional computer 21 so that the actual movement sequence of mark 1 (diagonal or some differently shaped curve) can be further processed as output signals of computer 21.

This processing, including the operation of calibrating key 11, takes place in the same way as described in connection with the preceding three embodiments. In connection with the embodiment of Figure 4, it is pointed out that the individual magnification ranges can be supplied to two stores 14, 15 either by means of adjusting device 6, range switch 61 and signal converter 19 or by range switch 16. To illustrate these possibilities, range switch 16 is indicated in dashed lines in Figure 4.

While certain advantageous embodiments have been chosen to illustrate the invention, it will be understood by those skilled in the art that various changes and modifications can be made therein without departing from the scope of the invention as defined in the appended claims.

Claims (8)

1. An apparatus for producing and digitally displaying a length measurement of an object positioned in the optical path of a microscope of the type including an eyepiece having a measurement mark carrier with a measurement mark thereon, the carrier being movable transversely with respect to the optical path, the apparatus including:: transducer means to be coupled to the carrier for producing output signals representative of positions of said carrier; memory means for selectively storing said output signals; means coupled to said transducer means and said memory means for producing a measurement signal representative of the distance between two positions of said measurement mark; range swtich means for establishing a predetermined range of length measurements; means responsive to said range switch means and said measurement signals for producing a scaled signal indicative of a dimension represented by the two positions; and means for displaying said scaled signal.

2. An apparatus according to claim 1, wherein said range switch means includes a keyboard and said means for producing a scaled signal includes second and third memory devices directly connected to said keyboard.

3. An apparatus according to claim 2 for use with a microscope having a continuously variable zoom lens, said apparatus further including an interpolator for automatic interpolation of intermediate values of the magnification, said interpolator being connected between said signal converter and between said second memory and a third computing element in said means for producing a scaled signal.

4. An apparatus according to claim 1 for use with a microscope having an objective lens structure having selectable magnification ranges, and wherein said range switch means of said apparatus is adapted to be coupled directly to said lens structure to be concurrently changed therewith, said apparatus further including second and third memory devices, and signal converter means for coupling signals from said range switch to said second and third memory devices.

5. Apparatus for producing and digitally displaying a length measurement substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

6. A microscope including apparatus according to any preceding claim.

7. A microscope according to claim 6, wherein said carrier is movable in two directions perpendicularto each other, each direction having associated therewith respective transducer means, memory means and means for producing a measurement signal.

8. A microscope including apparatus for producing and digitally displaying a length measurement constructed and arranged substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.