A laser attenuator applied to MALDI-TOF-MS

Abstract

The application belongs to the field of laser attenuators, and particularly relates to a laser attenuator applied to MALDI-TOF-MS, which comprises an outgoing optical fiber seat, an incoming optical fiber seat, a focusing lens, a 1 / 4 wavelength wave plate, a high-precision steering engine, polarizing plates and attenuation plates, and a driving mechanism for driving the attenuation plates to be inserted into and removed from the light path, the outgoing optical fiber seat is located on the incoming light side of the focusing lens, the outgoing light side of the focusing lens is provided with the 1 / 4 wavelength wave plate, the 1 / 4 wavelength wave plate is installed on the high-precision steering engine and used for adjusting the rotation angle of the 1 / 4 wavelength wave plate, the outgoing light side of the 1 / 4 wavelength wave plate is provided with two polarizing plates with orthogonal polarization directions, the incoming optical fiber seat is located on the outgoing light side of the two polarizing plates with orthogonal polarization directions, a plurality of groups of attenuation plates are arranged between the incoming optical fiber seat and the two polarizing plates with orthogonal polarization directions, and the attenuation plates are respectively installed on the driving mechanisms; the attenuator can greatly improve the adjustment precision by restricting the laser adjustment range to the vicinity of the required energy range, and is suitable for further popularization and application.

Description

Technical Field

[0001] This invention relates to the field of laser attenuator technology, and more specifically to a laser attenuator applied to MALDI-TOF-MS.

[0002] Background Techniques

[0003] As a crucial component in matrix-assisted laser desorption / ionization time-of-flight mass spectrometry (MALDI-TOF-MS), the laser output parameters of medical lasers directly impact the quality of MALDI-TOF-MS identification results. Currently available lasers meet the requirements of MALDI-TOF-MS in terms of wavelength, maximum energy, and pulse width. However, in practical applications, the highest energy output of commercially available medical lasers (≥70 μJ) far exceeds the detection requirements of MALDI (0-5 μJ for proteins, 10-20 μJ for nucleic acids), while the adjustment precision is too low (approximately 1-2 μJ). This results in the inability to adjust the laser energy to the optimal level for different test samples during MALDI-TOF-MS use, thus limiting the improvement of resolution, sensitivity, and quantitative performance of MALDI-TOF-MS results. Summary of the Invention

[0004] To address the above problems, this invention provides a laser attenuator for use in MALDI-TOF-MS.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A laser attenuator for MALDI-TOF-MS includes an output fiber optic mount, an input fiber optic mount, a focusing lens, a quarter-wave plate, a high-precision servo motor, polarizers, attenuators, and a driving mechanism for inserting and removing the attenuators from the optical path. The output fiber optic mount is located on the input side of the focusing lens. The output side of the focusing lens has a quarter-wave plate, which is mounted on the high-precision servo motor for adjusting the rotation angle of the quarter-wave plate. The output side of the quarter-wave plate has two polarizers with orthogonal polarization directions. The input fiber optic mount is located on the output side of the two orthogonal polarizers. Several sets of attenuators are arranged between the input fiber optic mount and the two orthogonal polarizers. The attenuators are respectively mounted on each driving mechanism.

[0007] Furthermore, a first anti-reflection window is provided between the quarter-wave plate and the focusing lens, and a photodiode is provided on the reflective side of the first anti-reflection window.

[0008] Furthermore, a second anti-reflection window is provided between the attenuator and the incident optical fiber seat, and a photodiode is provided on the reflective side of the second anti-reflection window.

[0009] Furthermore, the first anti-reflection window and the second anti-reflection window are orthogonally arranged, and the tilt angle of both anti-reflection windows is 45°.

[0010] Furthermore, the tilt angle of both polarizers is 45°.

[0011] Furthermore, the driving mechanism is an electromagnet, and the attenuation plate is fixedly installed on the telescopic end of the electromagnet.

[0012] The beneficial effects of this invention are as follows:

[0013] 1. The attenuator provided by this invention is compatible with all fiber optic output medical lasers on the market and is easy to use.

[0014] 2. This attenuator can constrain the laser adjustment range to near the required energy range, greatly improving the adjustment accuracy.

[0015] 3. The internal design of this attenuator fully considers laser loss, and it can actually output more than 80% of the energy of the original laser.

[0016] 4. The attenuator provided by this invention is equipped with a separate fast laser synchronization trigger, so adding this attenuator will not cause laser triggering timing errors.

[0017] 5. The attenuator provided by this invention is equipped with a separate energy detection diode, which can synchronously output the energy output magnitude after calibration. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention.

[0019] Figure 2 The waveform diagram of the first photodiode in the implementation example. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] See attached document Figure 1As shown, a laser attenuator for MALDI-TOF-MS includes an output fiber optic mount, an input fiber optic mount, a focusing lens, a quarter-wave plate, a high-precision servo motor, a polarizer, an attenuator, and a driving mechanism for driving the attenuator to insert into and move out of the optical path. The output fiber optic mount is located on the input side of the focusing lens, and a quarter-wave plate is provided on the output side of the focusing lens. The focusing lens is used to refocus the laser onto the output fiber optic mount at the exit. The quarter-wave plate is mounted on the high-precision servo motor and is used to adjust the rotation angle of the quarter-wave plate.

[0022] The 1 / 4 wavelength waveplate has two polarizers with orthogonal polarization directions on the light-emitting side, and the tilt angle of the two polarizers is also 45°. The orthogonal arrangement of the polarizers can avoid the optical path deviation caused by the thickness of the lens.

[0023] The optical fiber holder is located on the light-emitting side of two polarizers orthogonal in polarization direction. Several sets of attenuators are arranged between the optical fiber holder and the two polarizers orthogonal in polarization direction, and each attenuator is mounted on a driving mechanism. In this embodiment, an electromagnet is used as the driving mechanism, and the attenuators are fixedly mounted on the telescopic end of the electromagnet. The electromagnet is a telescopic electromagnet used to control whether the attenuators enter the optical path; the number of attenuators can be used according to requirements.

[0024] During the use of attenuators, energy adjustment precision is improved by inserting attenuators into the optical path, and the maximum output energy can be reduced. Assuming a laser input energy of 90 μJ and a target energy of approximately 5 μJ, the minimum adjustable precision without an attenuator is 1 μJ (90 / 90), with an adjustable range of 0-90 μJ. When a 50% transmittance attenuator is inserted, the adjustable precision increases to 0.5 μJ, and the adjustable range decreases to 0-45 μJ.

[0025] Furthermore, a first anti-reflection window is provided between the quarter-wave plate and the focusing lens, and a photodiode is disposed on the reflected light side of the first anti-reflection window. A second anti-reflection window is provided between the attenuator and the incident fiber seat, and a photodiode is disposed on the reflected light side of the second anti-reflection window. The tilt angle of both anti-reflection windows is 45°, and the first and second anti-reflection windows are orthogonally arranged. The orthogonal placement of the windows avoids the beam direction deviation introduced by the lens thickness. The two laser anti-reflection windows reflect a small amount of laser light to the photodiodes, and the photodiodes output corresponding electrical signals. Among them, the first photodiode on the left can receive the laser-generated pulse electrical signal as a trigger, and the second photodiode can evaluate the energy level by sensing the intensity of the attenuated laser light.

[0026] During operation, the laser beam can be directly introduced into the attenuator via optical fiber. The laser beam exits the output fiber seat, passes through a focusing lens, and then sequentially passes through a first anti-reflection window, a quarter-wave plate, and two polarizers orthogonal to the polarization direction. The laser beam passing through the first anti-reflection window is converted from linearly polarized to circularly polarized by the quarter-wave plate. It then passes through the two orthogonally polarized polarizers. The quarter-wave plate's angle (0-45°) is controlled by a high-precision servo motor (minimum rotation angle 0.5°), allowing for 0-100% output adjustment. The light emitted from the polarizer passes through the attenuator and the second anti-reflection window before entering the input fiber seat at the exit. If there is no attenuator in the optical path, the light emitted from the polarizer directly passes through the second anti-reflection window and enters the input fiber seat at the exit.

[0027] This embodiment further provides an implementation example using the above-described technical method:

[0028] Laser parameters: laser wavelength is 355nm, maximum laser intensity is 70μJ, laser frequency is 100Hz, and laser pulse width is 1.5ns.

[0029] Device parameters: Focusing lens diameter 15mm, focal length f=100mm; 45° antireflection window 15*15*1mm square plate with 355nm antireflection coating; PD uses nanosecond-level fast diode; servo uses magnetically controlled stepper servo; waveplate 1 / 4 waveplate size, diameter 20mm; polarizer 15*15*0.5mm; attenuator 2 pieces with 50% transmittance; fiber optic coupler is SM905 standard connector.

[0030] Practical application: ① Laser without attenuator: adjustable range 0-65μJ (optical path and coupling energy loss), minimum adjustment precision 0.72μJ; ② Laser with 50% attenuator: adjustable range 0-32.5μJ (optical path and coupling energy loss), minimum adjustment precision 0.36μJ; ③ Laser with 50% and 50% dual attenuators: adjustable range 0-16.2μJ (optical path and coupling energy loss), minimum adjustment precision 0.18μJ.

[0031] See attached document Figure 2 As shown in the figure, the first photodiode on the left can output a pulse signal of about 1.7V, and the rise time of this signal is only 3.6ns, which means it has a fast triggering speed for laser pulse signals.

[0032] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser attenuator for MALDI-TOF-MS, characterized in that, The system includes an output fiber optic mount, an input fiber optic mount, a focusing lens, an anti-reflection window, a quarter-wave plate, a high-precision servo motor, a polarizer, a photodiode, an attenuator, and a driving mechanism for inserting or removing the attenuator from the optical path. The output fiber optic mount is located on the input side of the focusing lens. The output side of the focusing lens is sequentially provided with a first anti-reflection window and the quarter-wave plate. The quarter-wave plate is mounted on the high-precision servo motor to adjust its rotation angle. The output side of the quarter-wave plate is provided with two polarizers with mutually orthogonal polarization directions, and both polarizers are 4... The optical fiber is tilted at 5°; the optical fiber holder is located on the light-emitting side of the two polarizers; several sets of attenuators are arranged between the optical fiber holder and the two polarizers, and each set of attenuators is installed on the corresponding driving mechanism for insertion or removal from the optical path; a first photodiode is arranged on the reflective side of the first anti-reflection window; a second anti-reflection window is arranged between the attenuator and the optical fiber holder, and a second photodiode is arranged on the reflective side of the second anti-reflection window; the first anti-reflection window and the second anti-reflection window are placed orthogonally to each other and both are tilted at 45°.

2. The laser attenuator for MALDI-TOF-MS according to claim 1, characterized in that, The driving mechanism is an electromagnet, and the attenuation plate is fixedly installed on the telescopic end of the electromagnet.

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