JPS6232673A - Sequence pulse solid laser and transient holography apparatus using the same - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a sequence pulsed solid-state laser and a transient holography device using the same, and more particularly to a sequence pulsed solid-state laser that can be used in a transient bolography device.

Holography is one of the important laser application areas. With the development of holography and its applications in measurement, analysis and other scientific fields, there has been an urgent need to be able to obtain transient bolograms sampled at regular time intervals about the object to be imaged. Engineering implementation requires that these transient bolograms be of high quality and that the sampling time interval between two side-by-side holograms be controllable. To meet this requirement, the laser, the central device of the holographic device, must produce a sequence of laser pulses, each laser pulse having good temporal and spatial coherence, and the light of each laser pulse A sequence of laser pulses whose intensities are approximately equal to each other and constant, the time interval between any two consecutive laser pulses is adjustable, and the adjustment range is sufficiently large, i.e. the time interval can be made as small as desired. It is required to be able to output.

<Prior art> As shown in FIG. 1, a typical laser used in a pulse holography device according to the prior art has an etalon 1,
Aperture stop 2, pumping light [3, ruby rod 4, pair of polarizers 5, electro-optic Q switch 6, total reflection diaphragm 7
A sequence of giant pulses is generated by repeatedly switching the Q-switch on and off for a single ruby rod. moreover,
An electro-optic or acousto-optic synchronous deflector is placed at the laser output to create a framed photograph. A typical laser of this type is ApOIIOLasers C
IMP produced by oi+pany in 1984
Pulsefo, known as ART I(TM). There are 2 valves for use in graphics equipment.

However, when this type of conventional laser is used in a transient bolography device, the following difficulties arise, which have not been overcome by the prior art. That is, (a) in conventional lasers, it is very difficult and required to maintain the peak power of each giant pulse substantially constant when arbitrarily adjusting the time interval Δt between two consecutive pulses; This is even impossible in principle if the time interval is smaller than the rise time of the giant pulse. (b) In conventional lasers, it is impossible to infinitely reduce the minimum value Δt min of the time interval Δt between two aligned lasers.

This value Δt min is 0A, which corresponds to the time resolution Δtr of the two-exposure hologram in holographic interferometry.
The aforementioned two-pulse ruby laser holography device, produced in 1984 by pollo La5er C0III) anV, makes it possible to adjust Δt in the range of 1 microsecond to 500 microseconds, with Δt 1
The minimum value of n is 1 microsecond. However, this technology index complicates the structure of the laser power supply and makes the device difficult to manufacture. (C) There are mainly two ways to improve the coherence of laser pulses in the prior art: improving the homogeneity of the ruby bar and improving the technology index of the etalon. But part 2
Using two methods brings great difficulties to the device fabrication process. Also, the presence of an electro-optic Q-switch in the optical resonant cavity severely limits the improvement of the coherence of the laser pulse using the two methods described above. □(d
) Conventionally, a synchronous deflector must be placed at the output end of the laser to create a framed photo.

If a deflection technique is used during the exposure process of the substrate, a displacement of the 1f dome with respect to the holographic substrate occurs such that the interference batten is deflected, which deteriorates the quality of the hologram.

<Summary of the Invention> The purpose of the present invention is to overcome the conventional extraction technique. The object of the present invention is to provide a new type of sequentially pulsed solid-state laser and transient holography device using a laser that can overcome the above-mentioned difficulties. This laser according to the invention can simultaneously and continuously output as many giant pulses as desired with good temporal and spatial coherence to each other from different spatial locations within a single optical resonant cavity. Furthermore, the time interval Δt between any two consecutive laser pulses in the pulse train is adjustable and its minimum possible value Δt
min can be reduced to zero. Not only can the peak power of each sequence laser pulse be controllable and remain stable while arbitrarily adjusting the Δt, but also there is no high requirement on the power supply and the deflection to create a framed photograph. It is possible to eliminate the need to use technology.

EXAMPLE A sequence pulsed laser according to the invention as shown in FIG. 2 outputs N optical giant pulse paths with good coherence from different spatial locations within a single laser resonant cavity, either simultaneously or sequentially. A mode selection etalon A, N solid-state laser active substance rods C...CN arranged in parallel or side by side in the same optical resonance cavity, and the above-mentioned in the same cavity. N pumping flash lamps B1 arranged corresponding to N active substance rods...
ye) includes a Q-switch D, a total internal reflection diaphragm E and a pump control 3F for controlling the trigger time of each of the N flash lamps;

Next, an embodiment of the sequence pulse laser transient holography apparatus according to the present invention will be described with reference to FIG. FIG. 3 is similar to FIG. 2, except that in FIG. 3 N is 4 and G is a holographic recording device. In the apparatus of this embodiment, a ruby rod is selected as the solid active substance, a Daicel is selected as the Q switch, and a xenon flash lamp is selected as the pumping flash lamp, or so-called pumping light source. The Daicel in this embodiment is designed and processed according to the requirements for the mode selection etalon, so that it not only plays the role of a Q-switch υ1, but also plays the role of mode selection. Pump controller F is actually a four-way interperiod time delay means for #1Jfll the trigger time of each of the four flash lamps.

The input signal applied to said means is one electrical pulse, but the output from said means are four electrical pulses with different or the same time delay values which cause said four xenon lamps to These are trigger signals for driving each. When inputting the electric trigger pulse to the 4-way inter-period time delay means, if the energy storage device for 8-way is pre-charged and the delay time of 8-way in the 4-way inter-period time delay means is When set to a defined value, the desired laser pulse train is generated from four optical paths within a single resonant cavity. If the delay time of the 8-way is preset to Δtj (j=1.2.3.4), each time interval between two side-by-side pulses is determined by the delay time tj.

In the transient holography device according to the invention, each ruby bar has its own pulse-forming path and the energy stored in each pulse path is spatially separated, so that the flash curve of the flash lamp and the laser power supply 2 exposure time resolution of the present holographic device for dynamic processes, since it is possible to keep the peak power of each pulse from different paths constant upon adjustment of the delay time Δt without requiring a change in the power of The possible values of Δtr have been increased to zero. The laser has low demands on the laser power supply, greatly reducing the size and weight of the device.

As is clear from the above, the present invention solves the problem of stabilizing the intensity of light, the controllable range of the time gap between two side-by-side light pulses, the problem of improving the coherence of sequence pulses, and the problem of high quality. completely solved the problem of creating frame photos.

In the embodiment described above, two sides of the glass plate in the etalon A and the Daicel port are used in the optical path to generate optical pulse beams from different positions within a single optical cavity with high coherence to each other. are parallel and 2
The two elements A and D must also be parallel. Furthermore, 1
N laser material rods C arranged in one optical resonant cavity
It is required that the directions of the crystal axes of the ONs are parallel to each other and that their optical lengths in the axial direction along which the light travels are strictly equal.

In the embodiments described above, the Q-switch is a passive Q-switch such as a Daicel.
Although the switch and laser materials are solid materials such as ruby rods, active Q-switches such as electro-optic Q-switch arrays and other types of laser materials such as semiconductor laser crystals may also be used in certain embodiments according to the present invention. It can be used for any purpose or effect.

In this embodiment of the transient holography device, a sequence pulse laser with four optical paths is selected based on the present invention, but a transient holography device using a sequence pulse laser with N optical paths is shown in FIG. It can be constructed in a similar manner. It is clear that the new type of laser according to the invention has incomparable advantages over pulsed lasers according to the prior art and can easily be used in other fields. Application of the laser according to the present invention to other fields is also within the scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the configuration of a typical conventional two-pulse ruby laser, FIG. 2 is a schematic diagram showing the configuration of an embodiment of the sequence pulse laser according to the present invention, and FIG. 3 is a schematic diagram showing the configuration of a four-pulse ruby laser according to the present invention. 1 is a schematic diagram illustrating an embodiment of a sequence pulse transient holography device having a sequence pulse transient holography device. Explanation of symbols 1... Etalon, 2... Aperture stop, 3... Pumping light source, 4... Ruby rod, 5... Pair of polarizers, 6... Electro-optic Q switch, 7. ... Total reflection diaphragm, A ... Mode selection etalon, B ... BN ... Pumping flash lamp, C
...CN...solid laser active substance rod, D...Q switch, E...total reflection diaphragm, F...pump controller, G...holography recording device.

Claims (6)

[Claims] (1) an optical resonant cavity; N solid-state laser material rods arranged in parallel or side by side within the optical resonant cavity; N pumping light sources corresponding to the N laser material rods;
A sequentially pulsed solid state laser comprising: a pump controller for controlling the trigger time of each of the pumping light sources; and means for Q-switching the resonator. (2) In the statement of claim 1, the resonant cavity includes a mode selection etalon and a total reflection diaphragm, and crystal axes of the N solid-state laser material rods are parallel to each other within the cavity. A sequence pulsed solid-state laser characterized by: (3) In claim 1, the pump controller is N-way synchronized time delay means, which are configured to drive each of the N pumping light sources in response to an input electrical signal. A sequence pulsed solid-state laser characterized in that it can output an N-way electrical trigger signal having a predetermined delay time. (4) The sequence pulsed solid-state laser according to claim 1, wherein the Q-switch means is a passive common dicell used by the N solid-state laser material rods. (5) A sequence pulsed solid-state laser according to claim 1, characterized in that the Q-switch means can be formed into an active Q-switch array for a specific purpose or effect. (6) A sequence pulsed laser transient holography device capable of increasing the possible time resolution to zero in two-exposure holographic interferometry of dynamic processes and creating high-quality frame holograms, comprising a holographic recording device, an etalon, a total internal reflection diaphragm, a die Q-switch, N solid-state laser material rods arranged in parallel or side by side within a single resonant cavity, N pumping flash lamps corresponding to said N laser material rods, and said flash. A sequenced pulsed laser transient holographic device of the new type, characterized in that it comprises a sequenced pulsed solid state laser of the new type, including a pump controller formed by an N-way synchronized time delay circuit for controlling the triggering time of each of the lamps.