which optical reflection is that? 3D printer, auto leveling

[legacy]

they argued "auto leveling optical-reflection's sensor", I wonder what they have used 

[legacy]

Based on infrared sensor with two fix holes spaced 20mm.


Sharp GP2Y0A21YK0F, IR distance sensor (10cm-80cm) -


I'd like to see the data sheet of this optical reflection sensor used to auto leveling, and its response, it's said that it's "Based on infrared sensor ", but I don't know if it's similar to my SHARP GP2Y0A21YK0F IR distance sensor 

(and I guess NO, too inaccurate for the purpose of measuring micron)

[Marco]

I'd say it's a TCRT5000L with bend leads.

[legacy]

Description
The TCRT5000 and TCRT5000L are reflective sensors which include an infrared emitter and phototransistor in a leaded package which blocks visible light.
The package includes two mounting clips. TCRT5000L is the long lead version.

[legacy]

I just wonder about the analog part, I mean, the gain of the Operational Amplifier you have to use to amplify the output from TCRT5000L in order to see 1µm

is it possible?

[Marco]

The precision which can be attained mostly depends on the consistency of the reflectivity of the bed I think.

I think one half of the LM358 is used as a transimpedance amplifier and the other as a comparator.

[legacy]

Studying the data sheet, and looking around for professional solutions, I guess they(@PiBot-kit) say bullshit, I do not believe that sensor is able to have a resolution of nor 1um neither 0.1mm (100 um), I guess it's 0.5mm of resolution in the best case.

[Marco]

It's really hard to say, it sounds implausible but these sensors have a fairly wide beam and thus a fairly large surface reflecting and evening out any inhomogeneity in it. Over a long time it might not have repeatability with past measurements, but for a short term it might very well be able to very accurately match distances at different points which might be enough for this application.

As a pure end stop at constant temperature I wouldn't be surprised at all if it had micron level repeatability.