What Is a Stroboscope?
A stroboscope is an instrument for observation and measurement that emits a high-speed flashing light.
By turning the light on and off instantly, the trajectory and momentum of an irradiated object can be analyzed. They can be broadly classified into two categories: those that are activated by setting the number of flashes per unit time and those that are activated by an external signal.
The former is mainly used to measure motion, while the latter is used to measure timing. A wide variety of products are available from various companies, ranging from portable size for personal use to relatively large ones for industrial use.
Uses of Stroboscopes
Stroboscopes are mainly used for calibration of products such as tape recorders and record players, whose performance is directly related to the number of revolutions, and for engine ignition timing adjustment.
1. Calibration Work
In the case of calibration work, if a disk rotating at the specified speed of 100 RPM is marked and the stroboscope is set to blink 100 times per minute, the disk and the marked area will appear to be stationary.
Therefore, if the rotation speed is slower than the specified speed, the object irradiated by the stroboscope will appear to be rotating backward at 1RPM, and calibration can be determined to be necessary.
2. Ignition Timing Adjustment
When used for engine ignition timing adjustment, the strobe is illuminated at the timing when the first cylinder is ignited by the spark plug by interrupting the signal line to the ignition circuit of the first cylinder.
The strobe will then read the point where the scale on the crank pulley coincides with the mark on the cylinder block to determine the timing of the ignition.
In either case, “whether or not adjustment is necessary” and “the result of adjustment” are visually displayed in real time, enabling efficient work.
Principle of Stroboscopes
1. Afterimage Phenomenon of the Retina
The operating principle of the stroboscope is based on the “retinal afterimage phenomenon,” which is a phenomenon that is particularly common in human vision. This is a phenomenon in which a momentary change in light intensity continues for a certain period of time (said to be about 1/16 of a second). Specifically, it refers to a phenomenon in which a light source appears to our vision as if it had existed for a short period of time even after the light source has disappeared.
A stroboscope uses this visual effect to illuminate a fast-moving object with a blinking light for a brief moment and capture that moment as a “still image. This is similar to the time-lapse technique used in the video industry. 2.
2. Light Source for a Stroboscope
Xenon flashlamps and LED lamps are the most common light sources for stroboscopes. Xenon flashlamps provide a large amount of white light, while LED lamps consume less power, have a longer life, and can change light colors.
However, since these light sources are designed to illuminate objects with high light intensity, direct viewing with the naked eye should be avoided. This is because excessive stimulation of the retina may affect vision.
How to Select a Stroboscope
The choice of a stroboscope depends largely on how it is used and what features it requires. Therefore, the following points should be considered when selecting a stroboscope
1. Brightness
The brightness of a stroboscope depends on the environment and the object itself to be observed. A model with a stronger light output is suitable for bright places and large objects.
2. Luminous Frequency
A stroboscope with a higher light emission frequency is required when observing a fast-moving object or when observing minute movements in detail.
3. Type of Light Source
Xenon flashlamps and LED lamps are mainly used as light sources for stroboscopes. Xenon flashlamps provide powerful light output, but their drawbacks are high power consumption and short lamp life. LED lamps, on the other hand, consume less power, have a longer life, and can change light colors.
4. Portability and Durability
Depending on the environment of use, portability and durability may be important selection criteria. For use in harsh environments such as outdoors or in factories, choose a model with a rugged design and good dustproof and waterproof performance.
Other Information About Stroboscopes
1. Advantages of a Stroboscope
Unlike other devices that measure motion, such as rotation, acceleration, and position sensors, stroboscopes have the advantage of being extremely versatile. It can be used to observe the progress of chemical reactions, to diagnose pharyngeal cancer, and in many other areas.
2. Disadvantages of Stroboscopes
However, since a stroboscope is an instrument that uses light and contrast, it has some limitations: it must be illuminated from an appropriate distance and direction, it is not suitable for use in brightly lit areas, and if the contrast is too large, it can cause white spots. To cope with this, some models are equipped with an automatic exposure function, but in many cases it is difficult to take measurements, especially in bright outdoor locations.