Optical Phase Retarder for Eye Axial Length Measurement

Abstract

The invention relates to an optical phase retarder for measuring the length of the ocular axis. The optical phase retarder comprises a fixed first right-angle prism and two movable right-angle prisms. The second right-angle prism and the third right-angle prism are stacked vertically and located on a transverse movement platform. The transverse movement platform is driven by a motor to move, and therefore the second right-angle prism and the third right-angle prism move synchronously. The hypotenuses of the three right-angle prisms have the same angle, thereby being in fit on a straight line. Light ray of a light source achieves incidence and penetrating through the right-angle edge of the second right-angle prism or the third right-angle prism, reaches the right-angle edge of the first right-angle prism in a vertical incidence mode through the hypotenuse of the first right-angle prism, is reflected through a high-reflection film plated on the hypotenuse of the first right-angle prism and returns back in the same way, the light source is not moved, the transverse movement platform moves, and the light ray reaches the two right-angle prisms in an incidence mode to produce the distance difference so as to achieve phase delay. Linear scanning is achieved, no aberration is introduced, the structure is simple, the cost is low, and whole-eye scanning of the anterior segment and the posterior segment of the eye is achieved.

Description

technical field [0001] The invention relates to a medical optical instrument, in particular to an optical phase retarder for eye axial length measurement. Background technique [0002] The measurement of the axial length of the eye is based on the principle of optical interference or ultrasonic detection. The optical interference method can achieve non-contact, high-resolution and fast characteristics, while the ultrasonic method needs to contact the eye, the resolution is low, and the ultrasonic probe has pressure on the eye. The accuracy of the measurement results cannot be guaranteed. In the optical interference method, partial coherence or low coherence interference technology is used, and the light source adopts a light source with a certain bandwidth and good spatial coherence. In terms of interferometry, the optical phase of the reference arm and the sample arm can only achieve interference within the coherence length of the light source. . In order to realize the m...

AI Technical Summary

Problems solved by technology

[0003] In the optical coherence tomography system, the currently reported axial optical phase delay lines include: 1. Linear translation mirror, which is the simplest and longest axial scanning method; the structure is simple and the cost is low, but the main The disadvantage is that the volume is large, the running line is long, and the stability is affected by the mechanical structure; 2. The piezoelectric control parallel mirror has reliable performance and high stability, but the price is high and the scanning range is limited, which is not suitable for the eye axis length of the large scanning range Measurement; 3. Using rotating cube scanning method; scanning in this way can achieve a large scanning range, but it is difficult to install and debug, and the scanning is not linear, with dispersion and low duty cycle, which requires algorithm cooperation; 4. Rotating micromirror array , the system is nonlinear, has dispersion, has a certain duty cycle, low energy utilization rate, too complicated adjustment, high cost, and is not suitable for mass industrialization

5. Involute spiral mirror; it can realize the advantages of high speed, good linearity, simple adjustment, large scanning range, and no dispersion, but the production accuracy is too high and it is difficult to be practical

The system structure is complex, there are many components, debugging is difficult, and the cost is high.

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