In the upstream field of the lidar industry, international companies have profound accumulations. For example, in the field of optical devices, there are STMicroelectronics and Asia Optical (Taiwan, China); in the field of light sources, there are Philips Photonics and Thorlabs (which produces both light sources and optical devices); in the field of photodetectors, there are SensL (a subsidiary of ON Semiconductor) and Hamamatsu (Japan); and in the IC field, there are semiconductor giants such as Xilinx and Qorvo. Then, what is the Chinese name of Thorlabs? How to use a Thorlabs optical power meter? How to adjust it? Today, the editor will share the company profile of Thorlabs, as well as the usage tutorial of Thorlabs optical power meter, with the adjustment schematic diagram attached at the end of the article. What is the Chinese name of Thorlabs? The Chinese brand name of Thorlabs is 索雷博 (Suǒléibó). Thorlabs was founded in 1989 in Newton, New Jersey, USA. It is a leading photonics enterprise that rapidly grows and manufactures and distributes optomechanical, optical, and optoelectronic components and equipment. Thorlabs China Branch in Shanghai is a branch established by Thorlabs in Shanghai, China in 2009. Together with the Tokyo Branch, Thorlabs China Branch provides localized real-time sales and technical support services to customers in the Asian market. Tutorial for Using Thorlabs Optical Power Meter An optical power meter is an instrument used to measure absolute optical power or relative loss of optical power through a section of optical fiber. Simply put, it measures the attenuation degree of optical signals after transmission through optical fibers. Key Explanations - DET (Delete Data Key): Deletes measured data. - dBm/W REL Key: Switches the unit of measurement results; each press toggles the display between "W" and "dBm". - λLD Key: Switches wavelengths between 1310nm and 1550nm when in light source mode (1310nm is commonly used). - λ/+ Key: Switches between 6 reference calibration points: 850nm, 1300nm, 1310nm, 1490nm, 1550nm, and 1625nm. - SAVE/- Key: Stores measured data. - LD Key: Switches between optical power meter mode and light source mode. - POWER Key: Power switch. Usage Method 1. The "IN" port of the optical power meter is the input port, used in the receiving mode of the optical power meter. The "OUT" port is the output port, used in the light source mode of the optical power meter. Note: This interface uses an FC connector pigtail. 2. Settings for the left optical power meter in the figure below: Use the LD key to set it to light source mode, set the wavelength to 1310nm, and use the output (OUT) port. 3. Settings for the right optical power meter in the figure above: Use the LD key to set it to receiving mode (optical power mode), use the dBm/W REL key to switch units to view results, and use the SAVE/- key to store the measurement results. The allowable attenuation of the optical fiber depends on the actual situation. During on-site installation, the attenuation of the optical modem's optical receiver must be greater than -25dB. If the optical modem's optical receiver is less than -25dB, it indicates weak light, and on-site rectification is required. Precautions for Using Thorlabs Optical Power Meter 1. Under no circumstances should you look directly at the laser output port of the optical power meter, nor should you look directly at the light source when connecting to optical transmission equipment at the opposite end. This may cause permanent visual burns. 2. For battery-powered optical power meters, remove the batteries if not used for a long time. For rechargeable optical power meters, they must be charged and discharged once a month. 3. Protect the ceramic ferrule during use, and clean it with alcohol cotton once every three months. Thorlabs Adjustment Schematic Diagrams 1. Finding the Focal Plane of a Lens via Speckles The schematic diagram and operation method for determining the focal plane position of a lens using the laser speckle method are as follows. This method is simple to operate, especially suitable for lenses with very short focal lengths and small imaging sizes or complex lens systems. Schematic Diagram of Finding the Focal Plane Using the Laser Speckle Method Operation Diagram: Reflected light at the focal point forms strong speckles Move the aluminum foil (or other scattering objects) back and forth along the optical path. If the aluminum foil is outside the focal plane, the illuminated area on the aluminum foil is large, and the reflected light will form fine speckles on the screen; if the aluminum foil is exactly at the focal plane, the illuminated area on the aluminum foil is small, and the reflected light will form a strong speckle pattern. Below is a dynamic diagram of the actual operation. Be sure to pay attention to laser safety precautions during operation. Of course, the simplest method to determine the focal point of a lens is to image a distant object, which is equivalent to imaging an object at infinity at the focal point. 2. Beam Expanding and Collimation Verification of Lasers Since the output beam diameter of a laser is generally small, it is sometimes necessary to expand the beam before use. This can be achieved through a telescope optical path, where the expansion ratio is the ratio of the focal lengths of the two lenses. At this time, adding a pinhole near the focal point can eliminate the intensity noise of the beam, resulting in a cleaner output light. For optimal performance, a plano-convex lens should be used, with the flat side facing the focal point, as shown in the figure below. Simplified Diagram of Beam Expanding Optical Path: Pinhole Filtering to Eliminate Intensity Noise The collimation of the output beam can be verified using a shearing interferometer. After the laser enters the shearing interferometer, Fresnel reflections are formed on the front and rear surfaces of the 45-degree optical flat. The interference fringes of the two reflected beams are observed through the top scattering plate engraved with reference lines. If the interference fringes are parallel to the reference lines, the incident beam is collimated; otherwise, it is divergent or convergent. Working Principle of the Shearing Interferometer Verifying Collimator Performance via Shearing Interferometer: The interference fringes are always parallel to the reference lines, indicating that adjusting the focal length will not affect the collimation of the beam. 3. Aligning Optical Paths via Mirrors When building or adjusting a free-space optical path, two mirrors and two diaphragms or small holes are often used for optical axis alignment. The mirrors are mounted in optical adjustment frames with two adjustment degrees of freedom. Below are two typical configurations. The alignment can be performed as follows: Roughly align the two mirrors so that the beam does not deviate too much from the ideal position. Adjust mirror M1 to make the beam pass through diaphragm I1; at this time, the beam may be blocked by diaphragm I2. Adjust mirror M2 to make the beam pass through I2; if the beam is blocked by I1, it can be opened. Repeat the above two steps until the beam passes through the centers of both diaphragms simultaneously. Please note that use the first mirror M1 to align the beam with the first diaphragm I1, and use M2 to align with I2. The order must not be reversed, otherwise the optical path will quickly deviate. Error Analysis The maximum angular error of this adjustment method can be estimated by (D1-D2)/Δz. As shown in the figure below, D1 is the diaphragm diameter, D2 is the beam diameter, and Δz is the distance between the two diaphragms. Obviously, for a given beam diameter, increasing the diaphragm spacing or reducing the diaphragm aperture can reduce the alignment error. Reducing Alignment Error: 1. Increase the beam diameter. 2. Reduce the diaphragm aperture. 3. Increase the diaphragm spacing. The above is an introduction to the Chinese name of Thorlabs, the usage tutorial of Thorlabs optical power meter, and the adjustment schematic diagrams. Next time, we will introduce the usage methods of other optical products of Thorlabs. Source: Comprehensively compiled from online platforms such as Thorlabs 索雷博.