Miniaturized Solid-state Laser Emitter For Rangefinder

This technology relates to a solid laser transmitter for rangefinders in optoelectronic technology. A solid-state laser is a type of laser that uses a solid material as its gain medium, the part of the laser that amplifies light. Common solid-state laser materials include crystals, such as neodymium-doped yttrium aluminum garnet (Nd:YAG), and glasses. Solid-state lasers are widely used in industry, medicine, and scientific research. 
The solid-state laser transmitter usually used in rangefinders is shown in Figure 1. It is a laser composed of a laser crystal (1) (the front end of which is coated with a uniform semi-reflective dielectric film), a total reflection lens (5), and a dye sheet (3). To generate laser light, the dye sheet (3) and the total reflection lens (5) are located behind the laser crystal (1). The emitting objective lens (4) and the emitting negative eyepiece (2) constitute the Galilean telescope, that is, the output mirror, which is located in front of the laser crystal (1). The output mirror is used to compress the divergence angle of the output laser pulse. The shortcoming of common laser transmitters is that the divergence angle of the output laser pulse is relatively large, which makes it difficult to meet the performance requirements of the ranging machine, such as the ranging distance and false detection rate.
Although a smaller laser pulse divergence angle can be obtained by increasing the magnification of the Galileo telescope, that is, the transmitting mirror, it will inevitably lengthen the size and weight of the laser transmitter, which is impossible for a miniaturized rangefinder. Accepted. Although a smaller laser pulse divergence angle can be obtained by using an unstable laser cavity, the laser threshold increases due to the unstable laser cavity and the energy consumption increases, making it difficult to use for small rangefinders.
The purpose of this technology is to provide a miniaturized solid-state laser transmitter for a small laser rangefinder with a small laser pulse divergence angle and a low laser threshold.
The solution of this technology:
A miniaturized solid laser transmitter for rangefinders, which includes a laser crystal (1), a negative emitting eyepiece (2), a dye sheet (3) and a reflective objective lens (4). The negative emitting eyepiece (2) is still related to the emitting The objective lens (4) constitutes an output mirror, which is characterized in that the rear end surface of the laser crystal (1) is coated with a total reflection dielectric film layer (6), and the flat end of the emission negative eyepiece (2) is coated with a dielectric film with uneven reflectivity. Layer (7), dye sheet (3) is placed between the emitting negative eyepiece (2) and the laser crystal (1).
This technology not only maintains the advantages of the traditional laser transmitter parallel plane laser resonant cavity with low threshold and easy adjustment, but also has a dielectric film layer (7) with uneven reflectivity (e.g. Magnesium fluoride, zirconium oxide and other material layers), which greatly reduces the divergence angle of the laser pulse. At the same time, the total length of the laser pulse is further reduced due to the elimination of the total reflection mirror (5) in the existing solid-state laser transmitter.
The following is further described in conjunction with the accompanying drawings:
Figure 1 is a schematic diagram of the existing universal solid-state laser emitter combination.

Figure 1

Figure 2 is a schematic diagram of the combination of this technology.
As shown in Figure 2, the best embodiment of this technology is that the laser crystal (1) uses neodymium-containing yttrium aluminum garnet (Na:AyG, specification: 3×40mm), and the rear end surface of the laser crystal (1) is plated with a full The reflective dielectric film layer (6) (such as magnesium fluoride, zirconium oxide and other material layers), the emission objective lens (4) specification is φ14mm, the center thickness is 2mm, the magnification is 4, the emission negative eyepiece (2) specification is 5mm, the center thickness is 3mm, and a dielectric film with uneven reflectivity is coated on its flat end surface (7). The emission objective lens (4) and the emission negative eyepiece (2) are 30.72mm apart and together form the output mirror. The dye piece (3) that acts as a Q switch is 4.4mm in specification and is placed between the laser crystal (1) and the emitting negative eyepiece (2). It is 3.3mm away from the emitting negative eyepiece (2) and has an overall length of 79.75mm. With this arrangement, the divergence angle of the emitted laser pulse can be less than or equal to 0.7mrad.

                                                         Figure 2

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