Transparent object detection

A method comprising:

• transmitting, by a light source, light across a portion of a cup holding region of a beverage preparation machine, the beverage preparation machine comprising a beverage dispenser, the cup holding region located below the beverage dispenser, the light source, a receive, and a processor;
• receiving, by the receiver, at least a portion the light transmitted by the light source;
• determining, by the processor, whether a transparent cup has been sufficiently inserted into the cup holding region or is at a desired height by detecting:
• a trough in a light level of the portion of the light received at the receiver;
• or
• an inverted trough in a light level of the light transmitted by the light source;
• and
• upon making the determination that the transparent cup is not sufficiently inserted or at the desired height, preventing, by the processor, the beverage dispenser from dispensing a beverage.

An apparatus comprising:

• a holding region for an object having a transparent portion;
• a light source configured to transmit light across a portion of the holding region;
• a receiver configured to receive at least a portion the light transmitted by the light source;
• and
• a processor operably coupled to the receiver, the processor configured to determine whether the object has been sufficiently inserted into the holding region or is at a desired height by detecting:
• a trough in a light level of the portion of the light received at the receiver;
• or
• an inverted trough in a light level of the light transmitted by the light source;
• wherein the processor is further configured to, upon making the determination that the object is not sufficiently inserted or at the desired height, prevent a process from being carried out.