CN-115774338-B - Laser non-collimation beam expansion calibration method

Abstract

The invention discloses a laser non-collimation beam expansion calibration method, which is characterized in that a plurality of cylindrical mirrors are overlapped to correct the divergence angle in the process of gradually reducing the divergence angle, so that the collimation difficulty of an original single cylindrical mirror is optimized when the single cylindrical mirror encounters a large divergence angle (more than or equal to 70 degrees), the overlapping design of the plurality of cylindrical mirrors is also used for optimizing the laser spot size control mode which is realized by controlling the distance between the cylindrical mirrors, and the volume of control equipment after collimation is effectively reduced.

Inventors

• LIU YUZHE

Assignees

• 江苏塔帝思智能科技有限公司

Dates

Publication Date

20260505

Application Date

20221220

Claims (5)

1. 1. The method for calibrating the non-collimation and the beam expansion of the laser is characterized by comprising the following steps: step one, acquiring an actual illumination distance and a required radius of an illumination spot, and calculating a required divergence angle; Step two, measuring the laser in the laser Places or places Divergence angle at; Calculating the actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the fast axis direction; if the actual divergence angle of the first fast axis cylindrical lens is not calibrated to the required divergence angle, adding at least one fast axis cylindrical lens, so that the light beam passes through the added actual divergence angle of the fast axis cylindrical lens in the fast axis direction to be calibrated to the required divergence angle, and if the actual divergence angle of the first fast axis cylindrical lens is calibrated to the required divergence angle, directly carrying out the next step; Calculating the actual divergence angle of the light beam passing through the first slow-axis cylindrical lens in the slow-axis direction; If the actual divergence angle of the first slow axis cylindrical lens is not calibrated to the required divergence angle, adding at least one slow axis cylindrical lens, so that the light beam passes through the added actual divergence angle of the slow axis cylindrical lens in the fast axis direction to be calibrated to the required divergence angle, and if the actual divergence angle of the first slow axis cylindrical lens is calibrated to the required divergence angle, directly carrying out the next step; calculating the curvature radiuses of all the fast axis cylindrical lenses and the slow axis cylindrical lenses; Step eight, performing simulation experiments according to the curvature radiuses of the cylindrical lenses obtained by calculation in the step seven, if the collimation effect of the fast axis verification is not qualified, repeating the third step, the fourth step and the seventh step to recalculate the curvature radiuses of the required fast axis cylindrical lenses, performing simulation experiments, if the collimation effect of the slow axis verification is not qualified, repeating the fifth step, the sixth step and the seventh step to recalculate the curvature radiuses of the required slow axis cylindrical lenses, and performing simulation experiments; The method for calculating the actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the third step is as follows: setting the beam from the emission point The half divergence angle of the emitted light is The light beam is refracted at the M point on the plane side of the first fast axis cylindrical mirror, and the refraction angle is Then the second refraction occurs when the light passes through the elliptical cambered surface of the cylindrical lens, and the refraction angle is The included angle between the normal line at the secondary refraction point N and the x axis is The divergence angle of the finally obtained light beam is ; The actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the third step is calculated by adopting the following formula: The plane equation for the elliptical arc surface of the cylindrical mirror is set as follows: Wherein, the Is a semi-long axis of an elliptical cambered surface of the fast axis cylindrical mirror or the slow axis cylindrical mirror, The semi-minor axis of the elliptical cambered surface is a fast axis cylindrical mirror or a slow axis cylindrical mirror; from the law of refraction: ; ; Wherein, the Is the sine value of the angle between the incident light of the first plane and the normal line, For the refractive index of the lens, Is the sine value of the included angle between the emergent light of the first surface and the normal line, Is the sine value of the included angle between the emergent light of the second surface and the normal line, The sine value of the included angle between the incident light of the second surface and the normal line is the sine value; Let the linear equation MN of the light in the cylindrical mirror be: Wherein, the Is the coordinate of the N point on the Y axis, Is the coordinate of the N point on the X axis, Is the tangent value of the included angle between the emergent light of the first surface and the normal line, Is the distance of the light source from the first face of the cylindrical mirror, Is a semi-long axis of an elliptical cambered surface of the fast axis cylindrical mirror or the slow axis cylindrical mirror, Is the distance from the first face to the second face of the cylindrical mirror, Is the tangent of the half divergence angle of the beam; combination formula Sum formula Solving N point coordinates: ; ; the above two equations are simplified to obtain: ; ; Based on the normal slope at the N point It is possible to obtain: ; The formula for the law of reverse refraction can be obtained: ; ; Finally, calculating the divergence angle of the fast axis direction as ; Wherein, the And As an intermediate variable, the number of the variables, Is the divergence angle of the fast axis direction.
2. 2. The method of claim 1, wherein the calculation formula of the required divergence angle in the first step is as follows: ; Wherein, the For the illumination distance to be sufficient, For the radius of the illumination spot, The divergence angle required for the lens.
3. 3. The method of calibrating a non-collimated beam expander of claim 1, wherein the calculation formulas for calculating the radii of curvature of the fast axis cylindrical mirror and the slow axis cylindrical mirror in the seventh step are as follows: wherein a is the semi-major axis of the elliptical cambered surface of the fast axis cylindrical mirror or the slow axis cylindrical mirror, and b is the semi-minor axis of the elliptical cambered surface of the fast axis cylindrical mirror or the slow axis cylindrical mirror.
4. 4. The method of calibrating a non-collimated beam expander of a laser according to claim 1, wherein the actual divergence angle of the beam passing through the first slow axis cylindrical mirror in the fifth step is calculated as follows: the method for calculating the actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the third step is adopted Replaced by Calculating to obtain the actual divergence angle of the light beam passing through the first slow axis cylindrical lens; ; Wherein, the Is the inherent astigmatism of the semiconductor laser, For the total offset of parallel direction light passing through the fast axis cylindrical mirror, For the thickness of the fast axis cylindrical mirror, For the first fast axis cylindrical lens distance from the light source, Is the distance between the two cylindrical mirrors.
5. 5. A method for calibrating a non-collimated beam expander of a laser according to claim 1, wherein the actual divergence angle of the beam passing through the added fast axis cylindrical mirror in the fourth step is calculated as follows: The method for calculating the actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the third step is adopted Replaced by Performing calculation, namely, the actual divergence angle of the light beam passing through the added fast axis cylindrical lens; ; Wherein, therein Is the inherent astigmatism of the semiconductor laser, Is the total offset of the light in the vertical direction as it passes through the cylindrical mirror, For the thickness of the fast axis cylindrical mirror, For the first fast axis cylindrical lens distance from the light source, Is the distance between the two cylindrical mirrors.

Description

Laser non-collimation beam expansion calibration method Technical Field The invention relates to the field of laser illumination calibration, in particular to a laser non-collimation beam expansion calibration method. Background In the laser lighting technology, aiming at semiconductor lasers with different divergence angles of fast and slow axes, a common method is to collimate the divergence angles of the fast axis and the slow axis respectively through two cylindrical mirrors with different focal lengths, so that the fast and slow axis beams collimated by the cylindrical mirrors are mutually parallel, then the parallel beams are expanded through a beam expander to change the angle of emergent light so as to realize beam convergence or divergence, in order to make the focal length ratio of the two cylindrical mirrors equal to the ratio of the divergence angles uniformly and to control the distance between the two cylindrical mirrors and a light source to be equal to the focal lengths of the two cylindrical mirrors respectively, compared with the method of independently designing a special-shaped mirror and an aspherical mirror, the method for collimating and expanding the beams greatly simplifies the design flow and becomes a popular design thought in the industry, but the method has poorer collimation effect of the cylindrical mirrors when encountering large divergence angles, especially over 70 degrees, and is difficult to control the uniform symmetry of the fast and slow axis light spots and the whole volume of the collimated device relative to the semiconductor lasers with small divergence angles. Disclosure of Invention The invention provides a method for calibrating non-collimation and beam expansion of a laser, which can solve the problems pointed out in the background technology. A laser non-collimation beam expansion calibration method comprises the following steps: step one, acquiring an actual illumination distance and a required radius of an illumination spot, and calculating a required divergence angle; Step two, measuring the laser in the laser Places or placesDivergence angle at; Calculating the actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the fast axis direction; if the actual divergence angle of the first fast axis cylindrical lens is not calibrated to the required divergence angle, adding at least one fast axis cylindrical lens, so that the light beam passes through the added actual divergence angle of the fast axis cylindrical lens in the fast axis direction to be calibrated to the required divergence angle, and if the actual divergence angle of the first fast axis cylindrical lens is calibrated to the required divergence angle, directly carrying out the next step; Calculating the actual divergence angle of the light beam passing through the first slow-axis cylindrical lens in the slow-axis direction; If the actual divergence angle of the first slow axis cylindrical lens is not calibrated to the required divergence angle, adding at least one slow axis cylindrical lens, so that the light beam passes through the added actual divergence angle of the slow axis cylindrical lens in the fast axis direction to be calibrated to the required divergence angle, and if the actual divergence angle of the first slow axis cylindrical lens is calibrated to the required divergence angle, directly carrying out the next step; calculating the curvature radiuses of all the fast axis cylindrical lenses and the slow axis cylindrical lenses; Step eight, performing simulation experiments according to the curvature radiuses of the cylindrical lenses obtained by calculation in the step seven, if the collimation effect of the fast axis verification is not qualified, repeating the third step, the fourth step and the seventh step to recalculate the curvature radiuses of the required fast axis cylindrical lenses, performing simulation experiments, if the collimation effect of the slow axis verification is not qualified, repeating the fifth step, the sixth step and the seventh step to recalculate the curvature radiuses of the required slow axis cylindrical lenses, and performing simulation experiments; the calculation formula of the required divergence angle in the first step is as follows: ; Wherein, the For the illumination distance to be sufficient,For the radius of the illumination spot,The divergence angle required for the lens; The method for calculating the actual divergence angle of the light beam passing through the first fast axis cylindrical mirror in the third step is as follows: setting the beam from the emission point The half divergence angle of the emitted light isThe light beam is refracted at the M point on the plane side of the first fast axis cylindrical mirror, and the refraction angle isThen the second refraction occurs when the light passes through the elliptical cambered surface of the cylindrical lens, and the refraction angle isThe includ