Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
  • G01B11/00—Measuring arrangements characterised by the use of optical techniques
  • G01B11/30—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces
  • G01B11/303—Measuring arrangements characterised by the use of optical techniques for measuring roughness or irregularity of surfaces using photoelectric detection means
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
  • G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
  • G11B7/123—Integrated head arrangements, e.g. with source and detectors mounted on the same substrate

Definitions

• the invention relates to an optical scanning head according to the preamble of claim 1.
• Such optical scanning heads are intended for installation in CD players and are used to read out the optical information stored on the CD (cornpact disk).
• This construction of the scanning head than for use in Kra ft poverty CD players' non-relevant further advantage that the beam path between the measuring light source and lens for manipulation is accessible because of the deflecting mirror in an opening of the housing of the scanning head is set ein ⁇ .
• the invention proposes, "to use a deflecting mirror, which is un verseläs ⁇ sig Although the measuring light, but is permeable to at least one wavelength in sichtba ⁇ ren region of the spectrum and not just on the specular front, but also on its sud ⁇
• An optical inspection device can then be placed directly behind this deflecting mirror, since the deflecting mirror is often a dielectric mirror from the outset, ie has a base body (generally made of glass) that is transparent to visible light it is sufficient in many cases, the particular already on Units for CD-scan scanning head, located to decrease slightly zugnature deflecting mirror, additionally on its back on optical quality -. u polish and then install again the observation optics, a commercial microscope -Ocular.
• the modification of the optical scanning head according to the invention thus allows a visual inspection of the respectively measured point of the workpiece surface at very low additional costs.
• the additionally provided optical parts do not need to be specially manufactured, they also do not require a lot of space and do not increase the weight of the scanning head significantly.
• the lenses used in CD scanning heads have a very short focal length (in practice 4.5 mm) and also have a small diameter (in practice 6-8 mm), these lenses correspond to microscope lenses in very good approximation. Together with a commercially available microscope eyepiece, a microscope integrated into the scanning head is thus obtained according to the invention.
• the scanning head and the observation device containing the illumination device form a compact, smooth-surface unit.
• the observation light strikes the measuring point exactly, so that the lighting device need only have low power.
• the development of the invention according to claim 7 is in view of the simple upgrade of such read heads an advantage, which do not offer any possibility for direct observation of the measuring point.
• observation light source can be spatially separated from the scanning head, which is advantageous with regard to keeping heat away, without additional ones for guiding the observation light to the measuring point precautions must be taken.
• FIG. 2 A schematic view of a modified eyepiece insert with an integrated image converter and a monitor connected to it, for use with the scanning head according to FIG. 1;
• Fig. 3 A similar sectional view as Figure 1 through a modified Abtstkopf.
• a scanning head is generally designated 10, which is used for high-precision measurement of surface roughness and surface structures on the surface of a workpiece 12.
• the scanning head 10 has a housing 14 which is essentially cup-shaped. In a lower opening 16 of the housing 14, an annular coil 18 is firmly inserted, which generates an axial magnetic field.
• the ring coil 18 works together with an annular permanent magnet 20 which is glued to the outside of an objective ring 22.
• the lens ring 22 holds a lens 24.
• the unit formed by the permanent magnet 20, the lens ring 22 and the lens 24 passes through the ring coil 18 with radial play and is supported by two leaf springs 26, 28 running parallel to one another, the springs of which are shown in FIG. 1 the section on the left is designed in the form of glasses so that the lens 24 remains free, while the section on the right is strip-shaped and is fixed at its extreme end by screws 30 to a web 32 of the housing 14.
• the leaf springs 26, 28 thus form an elastic parallelogram suspension for the lens 24.
• a semiconductor laser 34 working in red is fastened.
• the laser beam emitted by this passes through a semitransparent measuring mirror 36 and reaches a deflecting mirror 38.
• This consists of a glass base body 40 and a dielectric layer 42 applied to its underside, which is selected such that the deflecting mirror 38 receives the laser beam reflected. This then passes through the lens 24 and is imaged by the latter on the surface 'of the workpiece 12th
• the laser light reflected from the workpiece surface is collected by the objective 24 and reaches the measuring mirror 36 again via the deflecting mirror 38. This splits off part of the reflected measuring light and directs it onto a photoelectric transducer arrangement 44, the center of which is indicated at 46.
• the photoelectric converter arrangement 44 generates an output signal which depends on the position of the incident light with respect to the center line 46. This output signal arrives at an input amplifier 48 of an operating circuit assigned to the scanning head 10 and designated 50 in total.
• the operating circuit 50 contains circuits, not shown, which show the deviation of the currently received output signal of the converter arrangement 44 from that
• the operating circuit 50 determines an error signal for a power amplifier 52 which feeds the ring coil 18.
• IT ⁇ coil 18 is increased or decreased so long until the measuring 1 'c.htfleck on the transducer assembly 44 back on the telline Mit ⁇ is 46th This is the case when the distance between the lens 24 and the illuminated point on the surface of the workpiece 12 is exactly the effective focal length
• the lens 24 moves as axially when the scanning head 10 is moved over the surface of the workpiece 12 as this
• This measurement signal is provided on a line 54.
• the structure of the scanning head described so far corresponds to that of scanning heads as used in CD players for motor vehicles.
• the back of the glass base body 40 is polished to an optical quality. This can be done simply by taking the deflection mirror present in the commercially available CD scanning head out of the housing 14 and polishing it on its back to optical quality, after which the deflection mirror 38 is then reinserted into the housing 14
• the observation device denoted overall by 56 has a housing 58 which specifies a tube 60 and a lamp chamber 62.
• a halogen lamp 64 is arranged in the lamp chamber 62, the filament of which is imaged on the end of an angled light guide 68 via a lens 66. This passes through the tube 60 and, with its light guide section running vertically downward, lies on the axis of the objective, and thus also on the axis of the tube 60.
• a tube lens 70 which can be a plastic lens, is inserted into the tube 60.
• the tube lens 70 can be drilled through in the middle and the lower end of the light guide 68 can be passed through, as shown in the drawing.
• An eyepiece lens 72 is inserted into the upper end of the tube 60.
• the light emitted by the halogen lamp 64 reaches the workpiece surface via the light guide 68, through the deflection mirror 38 and via the objective 24, and is imaged there.
• the observation light reflected from the workpiece surface partly crosses the deflection mirror 38 again and reaches the eye of an observer through the tube lens 70 and the eyepiece lens 72.
• the objective 24, the tube lens 70 and the eyepiece lens 72 form a microscope, through which details of the workpiece surface can be viewed in an enlarged manner. That was watching
• the location of the workpiece surface is exactly the one that is also measured using the laser light.
• the semiconductor laser 34 excited by a zru sectionen supply circuit 74, the operation circuit 50 pulse-shaped, and the input amplifier 48 is designed as a phase-sensitive rectifier, so that non-modulated light components, which are also on the Wandleran-. 15 order 44 fall, do not affect the readjustment of the lens position.
• FIG. 2 shows an eyepiece 76 which is inserted into the upper end of the tube 60 instead of the eyepiece lens 72.
• the eyepiece 76 contains a solid-state image converter 78, such as is used in television cameras, that the real image of the workpiece surface generated by the tube lens 70 lies on the light-sensitive surface of the image converter 78.
• 25 converter 78 is connected to a monitor 82 via camera electronics 80, which can completely correspond to the commercially available electronics of portable television cameras.
• camera electronics 80 can completely correspond to the commercially available electronics of portable television cameras. The microscope image of the area of the workpiece surface that has just been measured can thus be viewed on the surface simultaneously with the
• the housing 58 is separated from the housing 14 and on it
• An adapter plate 84 is screwed on, which specifies a tube 86.
• a flexible coherent fiber cable 90 is fixed by means of an elastic clamping sleeve 88.
• This comprises a large number of properly bundled glass or plastic fibers and can thus transmit an image.
• the other end of the fiber cable 90 is fixed by an elastic clamping sleeve 92 in the lower end of the tube 60 of the housing 58.
• a mirror 94 which is semitransparent to the observation light, which deflects the observation light generated by the halogen lamp 64 and now converted into a parallel beam by the lens 66 into the fiber cable 90 and the light reflected back from the workpiece surface to the eyepiece lens 72 lets continue to run.

Landscapes

• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Length Measuring Devices By Optical Means (AREA)
• Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
• Optical Head (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6329815

Family Applications (1)

Country Status (5)

Cited By (1)

Families Citing this family (3)

Citations (5)

Family Cites Families (10)

• 1987
  • 1987-06-16 DE DE19873720079 patent/DE3720079A1/de active Granted
• 1988
  • 1988-06-14 WO PCT/EP1988/000527 patent/WO1988010405A1/de not_active Ceased
  • 1988-06-14 JP JP63505429A patent/JPH01503642A/ja active Pending
  • 1988-06-14 DE DE8888905756T patent/DE3865641D1/de not_active Expired - Fee Related
  • 1988-06-14 EP EP88905756A patent/EP0318566B2/de not_active Expired - Lifetime
  • 1988-07-14 US US07/328,587 patent/US4948984A/en not_active Expired - Fee Related

Patent Citations (5)

Non-Patent Citations (4)

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