Abstract

A laboratory-type camera is readily assembled using the following off-the-shelf components: a 3-mW He–Ne laser; an acoustooptic modulator; an electromechanical beam deflector; and a video (TV) tape recorder. The present camera is distinct in its operation in that submicrosecond laser flashes freeze the image motion while still allowing the simplicity of (millisecond range) electromechanical image deflection. The gating and pulse delay circuits of an oscilloscope synchronize the modulator and scanner relative to the subject being photographed. The pictures consist of a 3–64 frame sequence; the interframe time ranged from ~1 μsec to >1000 μsec. Video recording provides immediate monitoring of the picture quality and accuracy of synchronization. A number of variations are available for particular applications. For example, one can change the electrical pulsing to produce either streak or stroboscopic pictures instead of frames, and film can be substituted for video recording in order to retain more details of the image.

© 1980 Optical Society of America

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  1. By laboratory camera, we are emphasizing information gathering and display and not the resolution of conventional photographs. For example, the number of frames on the video screen ranges from 3 to 64. Thus, the resolution along each axis of the picture may be as low as 10 line pairs.
  2. Types and manufacturers are listed in trade journals, e.g., Laser FocusBuyers Guide (Newton, Mass., 1978).
  3. Note that stroboscopic pictures are readily produced but display only periodic behavior of the subject being photographed. However, this format has the advantage of requiring only low light intensities due to the integrating ability of the film or of the vidicon.
  4. Sony model VO-2850 video cassette recorder. The term field will be used to differentiate the (~17-msec) video frames from the microsecond type frames that appear on one field. Note that vidicons (and most other image tubes) integrate light and store it for ~1 sec or until read out, whichever is less. This is why the microsecond laser pulses are recorded and then read out later all on (essentially) one video field.
  5. Polaroid film 57 or 410, Polaroid Corp., Cambridge, Mass.
  6. GBC-ITC Corp., model CTC-6000 total darkness camera.
  7. Examples of acoustooptic modulators are Isomet (Springfield, Va.) model 2204 driver plus 1205 crystal or Intra Action (Bensenville, Ill.) model DE-70 driver plus ADM-70 crystal.
  8. Examples of resonant mirror scanners are model S-230 made by General Scanning (Watertown, Mass.) or L45 made by Bulova Watch Co. (Woodside, N.Y.).
  9. The galvanometer type scanners are G100PD scanner plus CCX102 driver made by General Scanning or ALS-300 scanner and PA driver made by Bulova Watch Co.
  10. The oscilloscopes must have two independent horizontal timing circuits, e.g., Tektronix model 545.
  11. The square-wave generator must accept an external gate signal, e.g., Hewlett-Packard model 214A or Altech model 501.

Other (11)

By laboratory camera, we are emphasizing information gathering and display and not the resolution of conventional photographs. For example, the number of frames on the video screen ranges from 3 to 64. Thus, the resolution along each axis of the picture may be as low as 10 line pairs.

Types and manufacturers are listed in trade journals, e.g., Laser FocusBuyers Guide (Newton, Mass., 1978).

Note that stroboscopic pictures are readily produced but display only periodic behavior of the subject being photographed. However, this format has the advantage of requiring only low light intensities due to the integrating ability of the film or of the vidicon.

Sony model VO-2850 video cassette recorder. The term field will be used to differentiate the (~17-msec) video frames from the microsecond type frames that appear on one field. Note that vidicons (and most other image tubes) integrate light and store it for ~1 sec or until read out, whichever is less. This is why the microsecond laser pulses are recorded and then read out later all on (essentially) one video field.

Polaroid film 57 or 410, Polaroid Corp., Cambridge, Mass.

GBC-ITC Corp., model CTC-6000 total darkness camera.

Examples of acoustooptic modulators are Isomet (Springfield, Va.) model 2204 driver plus 1205 crystal or Intra Action (Bensenville, Ill.) model DE-70 driver plus ADM-70 crystal.

Examples of resonant mirror scanners are model S-230 made by General Scanning (Watertown, Mass.) or L45 made by Bulova Watch Co. (Woodside, N.Y.).

The galvanometer type scanners are G100PD scanner plus CCX102 driver made by General Scanning or ALS-300 scanner and PA driver made by Bulova Watch Co.

The oscilloscopes must have two independent horizontal timing circuits, e.g., Tektronix model 545.

The square-wave generator must accept an external gate signal, e.g., Hewlett-Packard model 214A or Altech model 501.

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Figures (3)

Fig. 1
Fig. 1

Schematic representation of the present microsecond movie camera. All the optical components are placed on a 1 × 1.5-cm optical table; the components in the middle row are supported above an optical rail for ease in focusing and aligning.

Fig. 2
Fig. 2

A series of pictures showing a 50-μm ink droplet splattering on a 50-μm thick rubber sheet. (The ink viscosity is 1.8 centistokes, and velocity is 20 m/sec.) The interframe time is 8 μsec, and the exposure time is ~0.2 μsec. The split mirror provides a two-column image. The ink droplet is traveling from right to left and can be seen in the first frame. The second frame shows the droplet spreading as it contacts the surface. The remaining frame shows splattering as the ink first bounces rapidly upward and then breaks up into fine spray. Viscous drag due to air holds the mist essentially motionless over the rubber sheet for the remaining 80 μsec.

Fig. 3
Fig. 3

Block diagram of the triggering/gating circuits; the purpose of components is in parenthesis. Note that when a resonant mirror scanner is utilized a signal giving its angular position starts the time sequence. The relative position of the frames on the vidicon are thus reproducible.

Tables (1)

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Table I Comparison of Optical Scanners for Use with Microsecond Movie Camera

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