How to get product image or thumb URL? [Solved]

[legal]

What I want is to get URL of product image or product thumb so I can put this URL in this code:

<meta property="og:image" content="I want to put URL of product image here" />

Why I want to do this?

Because I want Facebook to display image of product when someone like some product in my shop.

[PRO]

MAYBE, this

$product->images->file_url_thumb   

or for large
file_url

[legal]

Thanks for help.

This is the code which give you URL of product thumb:
<?php echo $this->product->images[0]->file_url_thumb; ?>

[ncde]

Since VM 3.0.12 I think only "$this->product->images[0]->getFileUrlThumb()" does work.