Laser Scanners and the ILDA Test Pattern

Laser Scanners and the ILDA Test Pattern

by Newfeel Ho on Sep 19, 2023

The concept of the "ILDA Test Pattern" emerged with the aim of enabling users to precisely calibrate their laser scanners in accordance with the standards set forth by ILDA. To illustrate, a 30K scanner should ideally be calibrated to operate at an optical deviation of approximately 8 degrees or less.

How should the ILDA Test Pattern be properly employed?

The ILDA Test Pattern encompasses various parameters, but when it comes to issues related to speed, one parameter takes precedence - the circle that resides outside a square. As the scanner's speed increases, its ability to accurately track the circle diminishes, causing the circle to shrink. When the circle barely grazes the center of the square's sides, this signifies optimal circle tuning.
Balancing speed and width in scanning is a formidable challenge. This dilemma led to the establishment of specific scanning angles within the ILDA tuning standard. For scanners tuned to 30,000 points per second (30K), the prescribed angle is "approximately 8 degrees optical or less."
(At this 8-degree angle, the test pattern's width measures roughly 1/7th of the distance between the scanner and the screen). Pangolin's True 50,000 points per second (50K) scanners, on the other hand, are designed to meet ILDA requirements at a slightly narrower 7-degree angle. Additionally, other aspects of the test pattern are equally vital, such as ensuring the circle maintains a perfectly circular shape rather than becoming elliptical.

Parameters of the Testing Pattern

The ILDA Test Pattern encompasses a range of parameters, yet the paramount one for gauging scanner speed is the circle-in-the-square assessment. In this evaluation, it's imperative that the circular projection makes contact with the inner edges of the square, as illustrated on the right. (On your computer display, you will observe the circle positioned outside the square, as depicted above.) Additionally, it's crucial to designate the scan angle. The scanner's performance in correctly presenting the circle-in-the-square test improves as the scan angle widens.
Accurate Calibration
The primary factor related to speed is represented by the blue circle encircling the inner green square. Precision is key in drawing this circle. When the blue circle precisely intersects the midpoints of the sides of the green square, it signifies the accurate and ILDA-compliant speed setting.
Scanning at excessive speeds results in the blue circle being positioned within the confines of the green square.
Scanning at a Suboptimal Pace
When operating at slower speeds, as depicted in the illustration above, the blue circle extends beyond the boundaries of the green square.

What is the significance of a system's capability to present the ILDA Test Pattern? Does it simply imply that it can be exhibited, or does it pertain to the specific manner in which it is presented?

Within the laser display sector, the ILDA Test Pattern stands as the universally acknowledged benchmark. While a computer can potentially emit the ILDA Test Pattern's points at a rapid rate of 60,000 points per second, or even more, and the scanner may render a substantial portion of the ILDA Test Pattern with satisfactory results, this alone does not meet the required standard. In fact, certain aspects of it remain unsatisfactory.
When someone asserts that a particular scanner displays the ILDA Test Pattern at a specified speed and angle, laser technicians naturally assume that the scanner accurately reproduces all facets of the test pattern, unless expressly stated otherwise.

What sets apart "60K pps" from "ILDA 60K pps"?

Stating "my scanner operates at 60,000 points per second (pps)" implies its capability to display images while a computer generates 60,000 points per second, considering a specific scan angle.
While this statement might be factually accurate, it lacks practical significance. For laser enthusiasts, discussions regarding scanner performance should encompass not only the scanning speed but also details concerning the displayed images, the scan angle, and the quality of reproduction.
When one declares "my scanner runs at ILDA 60K pps," they are essentially conveying to the listener that "this scanner possesses the precision to faithfully replicate all components of the ILDA Test Pattern. This includes reproducing the circle in close proximity to the square's edges, provided the test pattern is executed at 60,000 points per second with a scan angle of 8 degrees or less."

Is the ILDA Test Pattern the most optimal choice among test patterns currently accessible?

The ILDA Test Pattern stands as an established industry benchmark, representing the widely accepted yardstick for evaluating scanner performance. Hence, it undeniably ranks as the most reliable and readily accessible test pattern in the field.

Can the ILDA Test Pattern effectively evaluate the performance of laser scanners?

It has a history of doing so. However, one limitation of the circle-in-the-square test lies in its ability to assess scanner performance at a singular point within the scanner's operational spectrum. This can be likened to evaluating a speaker's performance solely based on its accuracy in reproducing the note of middle C. While this assessment is informative, it fails to provide a comprehensive picture.
Relying on a single data point has been effective thus far, primarily because, historically, scanner performance has exhibited a similar trend at various scan rates, including 12K, 30K, and even 36K. Knowing the performance at one specific point has allowed for reasonable inferences to be drawn about performance at other points.
Nonetheless, the landscape might shift with the emergence of new scanners or alterations in scanner amplifier settings, potentially leading to modifications in the performance curve's shape. Consequently, it may become imperative for the lazer lights industry to reach a consensus regarding fresh test patterns that can furnish supplementary data.